Document:

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                                                                    EXHIBIT 10.8

                            MASTER LEASE AGREEMENT
                            DATED AS OF July 7,2000

The Master Lease AGREEMENT ("Master Lease"), is entered into as of July 7, 2000,
between Imperial Bank Equipment Leasing Division, a division of Aerial Bank
(hereinafter called "Lessor", having its principal place of business at 9920 La
Cienega Boulevard, Inglewood, California 90301, and Chorum Technologies, Inc., a
Corporation (hereinafter called "Lessee"), having its principal place of
business at 1303 E. Arapaho Road, Richardson, TX 75081-2444.

I.    LOCATION OF DEFINED TERMS

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                               Lease                                                 Lease
                              ------                                                 -----
Defined Term                  Section       Sub-Section    Defined Term             Section        Sub-Section
------------                  -------       -----------    -------------            -------        -----------
<S>                           <C>          <C>            <C>                      <C>            <C>
Acceptance Date                 II             D           Interim Rent                IV                A
Assignee                         X             A           Interim Rental Term        III                C
Casualty Value                  VII            C           Item of Equipment           II                A
Certificate of Acceptance       II             D           Lease Rate Factor           IV                A
Claims                          IX                         Lease Term                 III                D
Damage                          VII            A           Lien                       VIII               C
Daily Lease Rate Factor         IV             A           Loss                       VII                A
End of Term Notice              XII            A           Master Lease           Introduction
Equipment                       II             A           Purchase Documents          II                C
Event of Default                XI             A           Rent                        IV                A
Fair Market Value               XII            C           Rent Due Date               IV                B
Improvement                      V             C           Renewal Term               XII                D
Initial Term                    III            B           Rental Period Option        IV                B
Equipment Repair Notice        XIII            B           Schedule                    II                B
Equipment Inspection Fee       XIII            B           Seller                      II                C
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II.    LEASE OF EQUIPMENT

(A) Lease. Lessor agrees to lease to Lessee, and Lessee agrees to lease from
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Lessor, subject to the terms and conditions of the Master Lease, the equipment
and related operating systems and other software (collectively, together with
all substitutions and replacements, the "Equipment," and individually, an "Item
of Equipment" described in the equipment schedules (each a "Schedule") executed
from time to time pursuant to the Master Lease.

(B) Schedules. Each Schedule substantially in the form of that attached, when
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executed by Lessor and Lessee, shall constitute a separate lease and shall
incorporate by reference the terms and conditions of the Master Lease and any
additional terms and conditions agreed upon by the parties. In the event of a
conflict between the provisions of the Master Lease and a Schedule, the
provisions of the Schedule shall control.

(C) Equipment Procurement. Provided that no Event of Default or event which with
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notice or lapse of time or both would constitute an Event of Default has
occurred and is continuing and subject to the representations and warranties set
forth in Section VIII, Lessor may from time to time procure equipment requested
by Lessee and lease it to Lessee pursuant to the Master Lease and a Schedule;
provided, however, Lessor shall not purchase any Equipment unless Lessee is
unconditionally bound to lease it under the terms of the Master Lease and a
Schedule. Lessee

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authorizes Lessor, in reliance on Lessee's written request, to enter into
purchase orders, contracts or other documents ("Purchase Documents") for
acquisition of the Equipment with the seller of the Equipment ("Seller").

(D) Delivery Installation and Acceptance. Lessor or its designated
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representative shall arrange for delivery and installation of the Equipment at
the location specified in the applicable Schedule. Lessee shall pay all costs
associated with packing, transportation, taxes, duties, insurance, delivery,
installation, testing and support of the Equipment. Lessor will have no
liability for any delay or failure of the Seller to deliver or service the
Equipment or, license any software. Acceptance shall also be deemed to occur
upon the date of execution by Lessee of a Certificate of Acceptance in the form
of that attached. Lessee hereby authorizes Lessor to insert in any Schedule the
date of acceptance (the "Acceptance Date") for any Item of Equipment as well as
such items as serial numbers and the Equipment description and cost resulting
from any orders or change orders occurring after the Schedule is executed. In
the event of replacement by the supplier or manufacturer of any Equipment that
is determined after acceptance to be defective, the Equipment list and serial
numbers on the applicable Schedule shall be deemed amended to rafted the
substitute Equipment.

III.  TERM

(A) Master Lease Term. Unless otherwise extended by the parties hereto, the term
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of the Master Lease shall begin upon execution hereof by Lessor and Lessee and
continue through the last date on which any Schedule entered into pursuant to
the Master Lease remains in effect.

(B) Initial Term. The initial term under each Schedule shall begin on the first
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Rent Due Date occurring after the Acceptance Date under such Schedule and shall
continue through the end of the month of the number of months set forth in the
Schedule as the initial term ("Initial Term").

(C) Interim Rental Term. Prior to the commencement of the Initial Term under
    -------------------
each Schedule, Rent shall be due and payable to Lessor for the period beginning
on the Acceptance Date and continuing to the first Rent Due Date of the Initial
Term ("Interim Rental Term").

(D) Lease Term. "Lease Term" shall mean for each Schedule the Interim Rental
    ----------
Term, the Initial Term, and all Renewal Terms.

IV.  RENT

(A) Rent. Rent for the Equipment under each Schedule for each Rental Period
(Rents shall be an amount equal to the product of the percentage ("Lease Rate
Factor") set forth in such Schedule multiplied by the total cost of the
Equipment, as set forth in such Schedule. Rent for the Interim Rental Term
("interim Rent" or any other partial rent period will be prorated on a daily
basis in an amount equal to 1/30/th/ of the monthly Rent ("Daily Lease Rate
Factor"). Rent is payable in immediately available funds to Lessor at the
address or in accordance with the wire transfer instructions set forth in such
Schedule or as otherwise directed by Lessor.

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(B) Rent Due Date. Rent under each Schedule (other than Rent for the Interim
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Rental Term) shall be payable in advance, on each rent due date ("Rent Due
Date") of the period ("Rental Period"), as set forth in such Schedule. Rent for
the Interim Rental Term shall be due and payable on the first Rent Due Date of
the Initial Term.

(C) Past Due Amounts. To the extent permitted by applicable law, Lessee will pay
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on demand a late charge as stipulated under each schedule on each installment of
Rent and any other sums payable hereunder which remain unpaid for more than ten
days after the due date thereof.

(D) NONCANCELABLE RENT AND LEASE OBLIGATIONS. ALL LEASES HEREUNDER SHALL BE NET
    ----------------------------------------
LEASES. LESSEE'S OBLIGATION TO PAY RENT AND OTHER AMOUNTS DUE UNDER THE MASTER
LEASE AND EACH SCHEDULE SHALL BE ABSOLUTE AND UNCONDITIONAL, AND SHALL NOT BE
SUBJECT TO ANY SET OFF, COUNTERCLAIM, ABATEMENT, REDUCTION, RECOUPMENT,
INTERRUPTION OR DEFENSE FOR ANY REASONS WHATSOEVER THIS AGREEMENT SHALL NOT
TERMINATE NOR SHALL THE OBLIGATIONS OF LESSEE BE AFFECTED BY REASON OF ANY
DEFECT IN OR DAMAGE TO, OR LOSS OF USE OR POSSESSION OF, OR DESTRUCTION OF ANY
EQUIPMENT FROM ANY CAUSE WHATSOEVER. IT IS THE INTENTION OF THE PARTIES THAT,
RENTS AND OTHER AMOUNTS DUE HEREUNDER SHALL CONTINUE TO BE PAYABLE IN ALL EVENTS
IN THE MANNER AND AT THE TIMES SET FORTH HEREIN UNLESS THE OBLIGATION IS
TERMINATED PURSUANT TO THE EXPRESS TERMS HEREOF. THE MASTER LEASE AND THE
SCHEDULES CANNOT BE PREPAID OR TERMINATED BY LESSEE DURING THE TERM THEREOF
UNLESS AGREED TO IN WRITING BY LESSOR.

V. EQUIPMENT OWNERSHIP, USE, MAINTENANCE AND PROTECTION

(A) Ownership and Use. Lesser shall use the Equipment in a manner which will not
    -----------------
disqualify it for manufacturer maintenance, and in compliance with all laws,
rules and regulations of every governmental authority having jurisdiction over
the Equipment and within the provisions of all polities of insurance carried by
Lessee. Lessee shall obtain all permits, licenses or other authorizations
necessary for the operation and use of the Equipment Lessee shall pay all costs,
expenses, fees and charges incurred in connection with the use and operation of
the Equipment Upon Lessors request, Lessee will affix and maintain, in a
prominent place on each Item of Equipment, plates, tags or other identifying
markings indicating Lessor's ownership of the Equipment. Lessee shall not move
any Item of Equipment from the location set forth on the applicable Schedule
without the prior written consent of Lessor, which consent shall not be
unreasonably withheld. Lessor may upon reasonable prior notice to Lessee and
during regular business hours inspect the Equipment

(B) Lessors Entitlement to Tax Benefits. Lessee acknowledges that Lessor is the
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only party entitled to claim tax benefits provided by federal, state and local
income tax law to the owner of the Equipment ("Tax Benefits"); and Lessee agrees
to characterize the relationship herein established as a lease. If requested by
Lessor, Lessee shall furnish Lessor with records and other information necessary
to claim such Tax Benefits. Lessee shall not, and shall not permit any permitted
sub-lessee or assignee to, take or omit to take any action that may result in
the

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disqualification of the Equipment for, or any recapture of all or any portion of
the Tax Benefits afforded the Equipment

(C) Improvements. Lessee shall have the right, or the right to cause the Seller
    ------------
or another nationally recognized and experienced maintenance provider, to affix
or install any accessory, feature, device, improvement, modification, addition,
accession or upgrade ("Improvement") that is compatible with the Equipment In
the event an Improvement is financed, a party other than Lessor may not finance
it.  If Lessor finances any Improvement, it will be leased under the Schedule
covering the related Equipment and the Master Lease term for the Improvement
will be coterminous with such Schedule. Prior to the return of the Equipment
Lessee may (if it so chooses and if the Improvement is not financed by Lessor)
and shall (if Lessor so requests) remove the Improvements or cause the
Improvements to be removed by the Setter or another nationally recognized and
experienced maintenance provider, and restore or cause to be restored the
Equipment to its original state, ordinary wear and tear excepted. Lessee shall
not remove any original parts from the Equipment without Lessor's prior written
consent Any Improvements not removed from the Equipment upon its return or upon
the occurrence of an Event of Default shall, at Lessor's option, become the
property of Lessor.

(D) Maintenance. Lessee shall, at its own cost and expense and at all times
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during the Master Lease Term, take all actions necessary to maintain or cause to
be maintained by the Seller, manufacturer or a third party maintenance provider
reasonably acceptable to Lessor, the Equipment and all Improvements in good
working order, condition and repair, at the Equipment manufacturer's most
current engineering levels (including replacement of all parts which become
damaged or worn out), and in compliance with such maintenance and repair
standards as are set forth in the manufacturers manual pertaining to the
Equipment and as otherwise may be required to enforce warranty claims against
each vendor and manufacturer of each item of Equipment and in compliance with
all requirements of law. Lessee will not discriminate such maintenance between
owned and leased equipment Lessee shall comply with all instructions issued by
the manufacturer of the Equipment, and Lessee assumes and agrees to pay any cost
necessary to have the manufacturer re-certify that the Equipment will be
eligible upon resale or release by Lessor, for the manufacturers maintenance
contract at the manufacturers standard rates as required under Section XII(B).

(E) Insurance. (1) Lessee will insure for the following risks with insurers of
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recognized responsibility: (a) All risk of loss and physical damage to the
Equipment to an amount not less than the greater of (i) the fair market
replacement value or (ii) the aggregate Casualty Value of all Equipment from
time to time and; (b) Comprehensive public liability and property damage
insurance with respect to the condition, possession, maintenance operation and
use of the Equipment in an amount not less than $1,000,000 for each occurrence.
Such insurance shall be in full force and effect by not later than the
Installation Date for each item of Equipment and shall remain in effect until
such time as each item of Equipment has been returned to, and accepted by,
Lessor in accordance with the provisions of Section XII(B) hereof.

(F) Delivery of Insurance Certificates. Lessee shall deliver to Lessor and any
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Assignees) a valid Certificate of Insurance for each such insurance policy upon
the execution thereof and a Certificate of Insurance for each renewal policy not
less than 30 days prior to the expiration of

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the original policy or any renewal policy. Such insurance shall (1) Include as
additional parties insured and loss payees Lessor and any Assignee(s), (2)
provide that such insurance shall not be materially changed or canceled without
at least 30 days prior notice to Lessor and such Assignees, and (3) provide that
such policy shall not be invalidated by any negligence of, or breach of warranty
by, Lessee. Upon the request of Lessor, Lessee shall provide any additional data
related to the insurance as Lessor reasonably requests.

(G) Failure to Provide Insurance. Lessee acknowledges and agrees that if Lessee
    ----------------------------
fails to provide any required insurance or fails to continue such insurance in
force, Lessor may do so at Lessee's expense. The cost of any such insurance, at
the option of Lessor, shall be payable on demand or shall be added to the Master
Lease indebtedness. LESSEE ACKNOWLEDGES THAT IF LESSOR SO PURCHASES ANY SUCH
INSURANCE, THE INSURANCE WILL PROVIDE LIMITED PROTECTION AGAINST PHYSCIAL DAMAGE
TO THE EQUIPMENT, UP TO THE BALANCE OF THE MASTER LEASE; HOWEVER LESSEE'S EQUITY
IN THE EQUIPMENT MAY NOT BE INSURED. IN ADDITION, THE INSURANCE MAY NOT PROVIDE
ANY PUBLIC LIABILITY OR PROPERTY DAMAGE INDEMNIFICATION AND MAY NOT MEET THE
REQUIREMENT OF ANY FINANCIAL RESPONSIBILITY LAWS.

VI.  DISCLAIMER OF WARRANTIES; LIMITATION OF REMEDIES

LESSOR IS NOT A MANUFACTURER, SUPPLIER OR DEALER OF THE EQUIPMENT AND HAS NOT
INSPECTED THE EQUIPMENT PRIOR TO DELIVERY TO AND ACCEPTANCE BY LESSEE. LESSOR
HAS NOT MADE AND DOES NOT MAKE ANY REPRESENTATION OR WARRANTY, EXPRESS OR
IMPLIED, WITH RESPECT TO THE EQUIPMENT, INCLUDING, WITHOUT LIMITATION, ANY
REPRESENTATION OR WARRANT. AS TO TITLE, CONDITION, QUALITY, DESIGN, CAPACITY,
VALUE, DURABILITY, SUITABILITY, SAFETY, OR COMPLIANCE WITH ANY LAW. RULE,
REGULAT10N OR SPECIFICATION, AS TO MERCHANTABILITY OR FITNESS FOR USE OR FITNESS
FOR A PARTICULAR PURPOSE, OR AS TO PATENT, COPYRIGHT OR TRADEMARK INFRINGEMENT,
IT BEING AGREED THAT THE EQUIPMENT IS LEASED 'AS IS' AND THAT ALL SUCH RISKS, AS
BETWEEN LESSOR AND LESSEE, ARE TO BE BORNE BY LESSEE. LESSEE ACKNOWLEDGES THAT
IT HAS SELECTED THE EQUIPMENT FROM THE SELLER THEREOF ON THE BASIS OF LESSEE'S
JUDGMENT AND EXPRESSLY DISCLAIMS ANY RELIANCE UPON ANY STATEMENT MADE BY LESSOR
OR ITS AGENTS. LESSOR SHALL NOT IN ANY EVENT BE LIABLE FOR ANY INDIRECT,
CONSEQUENTIAL OR SPECIAL DAMAGES, EVEN IF LESSOR HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.

VII.  RISK OF LOSS

(A) Risk of Loss. Lessee shall bear the entire risk of the Equipment if damaged,
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destroyed or rendered permanently unfit or unavailable for use after its
shipment to Lessee and until it is accepted by Lessor in accordance with Section
XII(B) hereof.

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(B) Damage/Event of Loss. (1) In the event any item of Equipment is damaged to a
    --------------------
material extent by any occurrence whatsoever, Lessee shall promptly notify
Lessor and shall determine within 15 days of the date of such notice whether
such item of Equipment can be repaired If such Equipment can be repaired, Lessee
shall at its cost and expense repair such Equipment to its original condition.
(2) In the event any item of Equipment shall be lost, stolen, destroyed, damaged
beyond repair, or rendered permanently unfit or unavailable for use (through a
governmental taking or any other event), for any reason whatsoever (any such
occurrence being referred to as an "Event of Loss", Lessee shall promptly notify
Lessor and pay to Lessor, on the first day of the month immediately following
such Event of Loss, an amount equal to the Casualty Value applicable to such
item of Equipment calculated as of the immediately preceding Rent Due Date plus
any unpaid Rent and the installment of Rent for such item of Equipment due on
the Rent Due Date following the Event of Loss. After the payment of such
amounts, Lessee's obligation to pay further Basic Rent for such item of
Equipment shall cease, but Lessee's obligation to pay Interim Rent, if any, for
such item of Equipment, and to pay Rent for all other items of Equipment shall
remain unchanged. (3) Following payment of the Casualty Value and Rent for an
item of Equipment in accordance with the provisions sentence 2 of this Section
VII(B), Lessor shall transfer title to such item of Equipment to Lessee on an AS
IS, WHERE IS basis without representation or warranty.

(C) Casualty Value. The Casualty Value from time to time for any item of
    --------------
Equipment subject to a Schedule shall be an amount equal to the greater of *)
the item of Equipment's installed/in-place fair market value at the time of the
Casualty Value determination, or (2) 110% of the Item(s) of Equipment cost as of
the Acceptance Date, declining in even monthly steps to 15% at expiration and
remaining at that value thereafter.

(D) Disposition of Insurance and Other Proceeds. The proceeds of insurance or
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any condemnation of an item of Equipment for which an Event of Loss has occurred
shall be paid to Lessor (to the extent that Lessor has not previously received
all Casualty Value and other payments required to be made by Lessee pursuant to
the Master Lease), and the remainder, if any, shall be paid to Lessee. The
proceeds of insurance with respect to damage to an item of Equipment, the repair
of which, in the opinion of Lessee, is practicable shall unless an Event of
Default hereunder has occurred and is continuing be applied either to such
repair or to the reimbursement of Lessee for the cost of such repair.

VIII.  LESSEE'S REPRESENTATIONS, WARRANTIES AND COVENANTS

(A) Representations and Warranties. Lessee represents, warrants and covenants to
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Lessor, as of the date of the Master Lease and as of the date of each Schedule,
that: (1) Lessee's execution, delivery and performance of the Master Lease and
each Schedule have been duly authorized by all necessary action on the part of
Lessee, and the Master Lease and each Schedule constitute legal, valid and
binding obligations of Lessee; (2) the execution and delivery by Lessee of the
Master Lease and each Schedule and the performance of its obligations thereunder
do not conflict with or result In a material breach of Lessee's organizational
documents or applicable law, or any judgment order, writ, injunction, decree,
rule or regulation of any court, administrative agency or other governmental
authority, or any agreement or other instrument to which Lessee is a party or by
which it is bound; (3) there are no pending or, to the knowledge of

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Lessee, threatened actions or proceedings that could materially adversely affect
the ability of Lessee to perform its obligations under the Master Lease and the
Schedules; (4) there has been no material adverse change in Lessee's financial
condition since the date of the Master Lease; and (5) Lessee has obtained the
proper licenses to use, or ownership of, any software which is or may be used in
connection with the Equipment

(B) Assignment and Transfer.  LESSEE SHALL NOT, WITHOUT THE PRIOR WRITTEN
    -----------------------
CONSENT OF LESSOR SELL, TRANSFER, ASSIGN. SUBLEASE (EXCEPT, UPON PRIOR WRITTEN
NOTICE TO LESSOR, A SUBLEASE TO A WHOLLY OWNED OR CONTROLLED SUBSIDIARY OR TO
ITS PARENT), PLEDGE OR HYPOTHECATE THE MASTER LEASE, ANY SCHEDULE, THE EQUIPMENT
OR ANY PART THEREOF OR ANY INTEREST THEREIN. Lessee shall not, without the prior
written consent of Lessor, which shall not be unreasonably withheld, merge or
consolidate with any corporation or other entity (unless Lessee is the surviving
entity or the surviving entity continues the business of Lessee and assumes the
Master Lease and ail Schedules) and shall not sell, transfer or otherwise
dispose of all or any substantial part of Lessee's assets.

(C) No Liens. Lessee shall not directly or Indirectly create, incur, assume or
    --------
allow to exist any lien, mortgage, pledge, security interest, charge,
encumbrance, right, or claim of any kind ("Lien" on or with respect to the
Master Lease, any Schedule or any item of Equipment. Lessee will promptly notify
Lessor in writing of the existence of any Lien and will promptly, at Lessee's
expense, cause any such Lien to be duly discharged.

(D) Payment of Taxes. Lessee shall reimburse Lessor for, and indemnify and hold
    ----------------
Lessor harmless from, all sales, use, personal property, stamp or other taxes,
and all levies, imposts, duties, charges, fees, assessments or withholdings of
any nature whatsoever (other than those measured by Lessor's net income),
together with any penalties, fines or interest thereon which are at any time
levied, assessed or imposed on the Equipment or any interest of Lessor or Lessee
therein or on the sale, purchase, delivery, ownership, possession, use or
operation of the Equipment or the rentals or other amounts payable under this
Agreement or any Schedule. If requested by Lessor or if filing by Lessee is
required by law, Lessee shall prepare and file, or cause to be prepared and
filed, all necessary fortes for the assessment of such taxes and shall promptly
send to Lessor a copy of such filing.

(E) Financial Reports. Lessee shall upon execution hereof, and for the term of
    -----------------
the Master Lease and any Schedules, amendments, extensions and addendums
thereto, furnish or caused to be furnished to Lessor the following: (1) the
audited annual financial statements of Lessee within 120 days after the close of
each fiscal year; (2) quarterly financial statements in a form reasonably
acceptable to Lessor within 60 days after the close of each fiscal quarter, and
(3) monthly financial statements in a forth reasonably acceptable to Lessor
within 30 days after the close of each fiscal month.

(F) Further Assurances: Payment of Lessor's Expenses. Lessee shall promptly
    ------------------------------ -----------------
execute and deliver, or cause to be executed and delivered to Lessor such
further documents and take such further action as Lessor may from time to time
request in order to more effectively carry out the intent and purpose of the
Master Lease and each Schedule, protect the rights and remedies of

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Lessor created or intended to be created thereunder and perfect and protect
Lessor's interest in the Equipment Lessee shall pay all reasonable costs
(including reasonable legal fees and costs) and expenses incurred by Lessor in
the consummation or interpretation of the Master Lease or any Schedule; in
collecting or attempting to collect any sums owed under the Master Lease or any
Schedule; or in enforcing any of Lessor's rights or remedies under the Master
Lease or any Schedule. Lessee shall also pay all filing fees, Lien search fees,
recordation fees and related expenses reasonably incurred by Lessor in
connection with the Master Lease or any Schedule.

(G) Notification. Lessee shall notify Lessor within 10 days of any material
    ------------
changes in the management, ownership or control of Lessee.

IX. GENERAL INDEMNITY

(A) LESSEE SHALL INDEMNIFY HOLD HARMLESS AND DEFEND LESSOR AND ITS SUCCESSORS
AND ASSIGNS AND THEIR RESPECTIVE OFFICERS, DIRECTORS, EMPLOYEES AND AGENTS
AGAINST ALL CLAIMS DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THE
EQUIPMENT, THE MASTER LEASE OR ANY SCHEDULE, EXCEPT FOR CLAIMS RESULTING SOLELY
FROM LESSOR'S GROSS NEGLIGENCE OR WILLFUL MISCONDUCT. "CLAIMS" REFERS TO ALL
LOSSES LIABILITIES, DAMAGES, PENALTIES, EXPENSES (INCLUDING REASONABLE LEGAL
FEES AND COSTS), CLAIMS, ACTIONS AND SUITS, WHETHER IN CONTRACT OR IN TORT AND
WHETHER BASED ON A THEORY OF STRICT LIABILITY OF LESSOR OR OTHERWISE, AND
INCLUDES, BUT IS NOT LIMITED T0, MATTERS RELATING TO: (1) THE SELECTION,
MANUFACTURE, PURCHASE, ACCEPTANCE, REJECTION, OWNERSHIP, DELIVERY, LEASE,
POSSESSION, STORAGE, MAINTENANCE, USE, CONDITION, RETURN OR OPERATION OF THE
EQUIPMENT; (2) ANY LATENT DEFECTS OR OTHER DEFECTS IN ANY EQUIPMENT, WHETHER OR
NOT DISCOVERABLE BY LESSOR OR LESSEE; (3) ANY PATENT, TRADEMARK OR COPYRIGHT
INFRINGEMENT; AND (4) THE CONDITION OF ANY EQUIPMENT ARISING OR EXISTING DURING
LESSEE'S USE. (B) LESSOR SHALL PROMPTLY NOTIFY LESSEE OF ANY CLAIM AFTER RECEIPT
OF A WRITTEN NOTICE OF SUCH CLAIM BY LESSOR, AND LESSEE SHALL HAVE THIRTY (30)
DAYS TO ELECT TO DEFEND, COMPROMISE OR SETTLE THE CLAIM. IF LESSEE ELECTS TO
DEFEND THE CLAIM, (1) LESSOR SHALL HAVE THE RIGHT TO APPROVE LESSEE'S SELECTION
OF COUNSEL, WHICH APPROVAL SHALL NOT BE UNREASONABLY WITHHELD, AND SHALL HAVE
THE RIGHT AT ITS ELECTION TO PARTICIPATE IN SUCH DEFENSE, AND (2) LESSEE SHALL
NOT BE RESPONSIBLE FOR ANY LEGAL FEES OR OTHER EXPENSES RELATING TO DEFENSE OF
THAT CLAIM THAT LESSOR MAY THEREAFTER ELECT TO INCUR LESSEE SHALL NOT CONSENT TO
ENTRY OF ANY JUDGMENT OR ENTER INTO ANY SETTLEMENT WITHOUT THE EXPRESS WRITTEN
CONSENT IF LESSOR. THIS INDEMNIFICATION OBLIGATION SHALL SURVIVE TERMINATION OR
EXPIRATION OF THE MASTER LEASE OR ANY SCHEDULE.

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X. LESSOR RIGHTS

(A) Assignment. Lessor (and any assignee of Lessor) shall have the right to
    ----------
sell, assign, transfer, pledge, mortgage or otherwise convey its interest in the
Master Lease, one or more Schedules, any or all of the Equipment or any of its
rights, interests or obligations with respect thereto, in whole or in part, to
one or more persons or entities (each, an "Assignee") without notice to, or
consent of, Lessee. Notwithstanding such assignment, Lessor shall not be
relieved of its obligations hereunder except to the extent of such assignment
Lessee agrees that if any Schedule is assigned, (1) Lessee shall, if instructed
by Lessor, pay all amounts due under such Schedule to the Assignee, (2) Lessee
shall execute such acknowledgments to such assignment as are reasonably required
by the Assignee to perfect and protect its right, title and interest in and to
the Equipment, the applicable Schedule and the Rent due thereunder, and (3)
Lessee shall not require the Assignee to perform any obligation of Lessor, other
than those that are expressly assumed by such Assignee, and shall not assert
against any Assignee any claim, defense, counterclaim or set-off that Lessee may
at any time have against Lessor.

LESSEE ACKNOWLEDGES THAT ANY ASSIGNMENT OR TRANSFER IN ACCORDANCE WITH THIS
SECTION BY LESSOR OR AN ASSIGNEE WILL NOT MATERIALLY CHANGE LESSEE'S DUTIES OR
OBLIGATIONS UNDER THE MASTER LEASE OR THE ASSIGNED SCHEDULE NOR MATERIALLY
INCREASE THE BURDENS OR RISKS IMPOSED ON LESSEE.

(B) Lessor's Performance of Lessee's Obligations. If Lessee fails to perform its
    --------------------------------------------
obligations under the Master Lease or any Schedule, Lessor shall have the right
but not the obligation, without releasing Lessee from any obligation hereunder
or under any Schedule, to perform any act or make any payment that Lessor
reasonably deems necessary for the maintenance and protection of the Equipment
and Lessor's interests in the Equipment and in the Master Lease and the
Schedules, and in exercising any such rights, incur any liability and expend any
amounts reasonably necessary to protect such Interests. All sums so incurred and
expended by Lessor, together with expenses (including reasonable legal fees and
costs) Incurred in connection therewith, shall be immediately due and payable by
Lessee and shall bear interest at the interest rate for late payments set forth
in the applicable Schedule (or such lesser rate or amount as may then be the
maximum permitted by applicable law), from the date so incurred or expended by
Lessor to the date payment is received by Lessor.

(C) Financing Statements. Lessor may, at its option, file with such authorities
    --------------------
and in such locations, as ft may deem appropriate, Uniform Commercial Code
financing statements relating to the Equipment, the Master Lease, the Schedules
and the rents payable thereunder. Lessee agrees to promptly execute and deliver
to Lessor any such financing statements requested by Lessor. provided that
Lessor may, at its option, file Uniform Commercial Code financing statements
signed by Lessor only, and if Lessee's signature is required by law, Lessee
appoints Lessor as Lessee's attorney-in-fact to execute such financing
statements or file a copy of the Master Lease or any Schedule as a financing
statement Lessee will promptly notify Lessor of any change in the location of
Its principal place of business or chief executive office.

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XI.  DEFAULT AND REMEDIES.

(A) Events of Default. An "Event of Default" shall occur hereunder and under all
    -----------------
Schedules if Lessee (1) fails to pay any installment of Rent or other payment
required hereunder or under any Schedule within the time period set forth in a
Schedule; (2) is in default subject to the terms of any other loan or lease
agreement with Imperial Bank or any other party: (3) fails to timely perform or
observe any covenant, condition or agreement set forth in the Master Lease or
any Schedule; (4) experiences a material adverse change in Its financial
condition as reasonably determined by Lessor; (5) becomes insolvent or makes an
assignment for the benefit of creditors, or institutes or has instituted against
it bankruptcy, reorganization or insolvency proceedings (and, in the case of any
such proceedings instituted against Lessee, such proceeding is not stayed or
dismissed within thirty (30) days), or a trustee, administrator or receiver
shall be appointed for Lessee or for a substantial part of its property; or (6)
makes any statement, representation or warranty in the Master Lease or any
Schedule that is false or misleading in any material respect when made.

(B) Remedies. (1) If an Event of Default occurs under the Master Lease, Lessor
    --------
may give Lessee notice of the Event of Default and upon the giving of such
notice or at any time thereafter do any or all of the following (as Lessor in
its sole discretion elects): (a) proceed by appropriate court action or actions
to enforce performance by Lessee of the applicable covenants and terms of the
Master Lease or to recover damages for the breach thereof; (b) take possession
(by summary proceedings or otherwise) of any or all items of Equipment subject
to the Master Lease without prejudice to any other remedy or claim herein
referred to; (c) hold, sell, lease, or otherwise dispose of, any or all items of
Equipment subject to the Master Lease, in any manner Lessor (in its sole
discretion) elects; (d) receive from Lessee upon demand for any or all Equipment
subject to the Master Lease the following amounts which Lessee shall be
obligated to pay: (i) any unpaid Rent past due (ii) as liquidated damages for
loss of bargain and not as a penalty, the aggregate Casualty Value for such
Equipment under the Master Lease in effect as of the date on which such Event of
Default occurred, (iii) all costs and expenses incurred in searching for,
taking, removing, keeping storing repairing, and restoring such items of
Equipment, (iv) all other amounts then owing by Lessee hereunder and (v) all
costs and expenses, including (without limitation) reasonable legal fees and
expenses, incurred by Lessor as a result of an Event of Default, or the exercise
by Lessor of its remedies under this Section XI(A) or in connection with any
bankruptcy proceeding of the Lessee (including, without limitation, fees and
expenses incurred in connection with relief from stay motions relating to the
Equipment cash collateral disputes, assumption/rejection motions relating to the
Equipment and disputes relating to any proposed plan and/or disclosure
statement); (e) by notice to Lessee, declare the Master Lease (for any or all
Equipment) canceled without prejudice to Lessor's rights in respect of all
obligations set forth in this Section XI(A) and any other obligations under the
Master Lease then accrued and remaining unsatisfied; or (f) avail itself of any
other remedy or remedies provided for by any statute or otherwise available by
law, in equity or in bankruptcy or insolvency proceedings; or (g) terminate any
other Lease that Lessor may have with Lessee.

(C) The remedies set forth in this Section XI(B), (Remedies), are not intended
to be exclusive, and each shall be cumulative. The amounts to be paid to Lessor
under clause (d) of Section XI(B) shall be increased by interest, at the Late
Charge Rate, to the date of receipt by Lessor of

                                 Page 10 of 15
<PAGE>

the amount payable under said clause, from the respective due dates of such
amounts or (with respect to costs, expenses, and losses for which Lessor is
entitled to payment or reimbursement under said clause) from the respective
dates incurred by Lessor.

(D) Any amounts received by Lessor as the result of its sale, lease during the
original tern hereof, or other disposition of the Equipment hereunder shall be
paid or applied in the following order: (1) to any remaining obligation of
Lessee under clause (d) of Section XI (B), (2) to reimburse Lessee for the
Casualty Value previously paid as liquidated damages, and (3) to Lessor, any
remaining balance.

XII. END OF LEASE TERM

(A) End of Term Notice. Lessee shall give Lessor no less than ninety (90) days
    ------------------
and no more than 365 days written notice prior to the expiration of the Master
Lease Term under any Schedule, as to whether it will purchase, return or extend
the tern of the Master Leased Equipment on the applicable Schedule at expiration
of the Master Lease Term ("End of Term Notice"). If Lessee fails to give timely
notice or fails to return the Equipment b Lessor upon expiration of the Master
Lease Term as provided herein, the Schedule shall continue in full force and
effect and will extend on a month to month basis at the applicable Rent, until
Lessee provides Lessor with ninety (90) days prior written notice of Lessee's
intent to purchase, return or extend the tern of the Master Leased Equipment on
the applicable Schedule. Such notice once given shall be irrevocable.

(B) Return. (1) Upon the expiration or other permitted termination of any
    ------
Schedule or any extension thereof ("Expiration Date"); Lessee, at its sole cost,
risk, and expense, will return to Lessor all, (but not less than all), of the
Equipment then subject to such Schedule to a location in the Continental United
States specified by Lessor. Lessee shall be responsible at its sole cost and
expense, for (a) the deinstallation, removal and packaging of the Equipment
(including, but not limited to, any and all software, all manuals, maintenance
records, maintenance record jackets, repair orders and all other similar
documents) in a manner suitable for cartage by a common commercial carrier
acceptable to Lessor, and (b) the transportation of the Equipment; upon written
notification by Lessor, as to the date and destination of the shipping. Such
Equipment upon return, shall be free and dear of all mortgages, liens, security
interest, charges, encumbrances and claims. If Lessor shall so require, Lessee
shall provide free and safe storage, as well as maintain sufficient insurance
coverage (as specified in the Master Lease) for such Equipment for a period not
to exceed 120 days from the Expiration Date or the last day of any extension
period therefor. (2) Upon return of such Equipment Lessor or its agent shall
inspect the Equipment If any item of Equipment is not returned to Lessor, it
shall be deemed to be a casualty and an Event of Loss during the Master Lease
Term. In the event Lessor determines that repairs, additions or replacements are
necessary to place the Equipment in the same condition as when originally leased
to Lessee (reasonable wear and tear excepted), which at a minimum will require
that the Equipment be in complete and running condition with no missing or
damaged components and/or certified as being eligible for the Sellers or the
manufacturers generally available maintenance contract at then prevailing
prices. (3) If Lessor determines that the Equipment (after Inspection) is
damaged or worn beyond normal wear and tear, Lessor or Lessors agent will
prepare an invoice which fully describes the repairs and the estimated cost

                                 Page 11 of 15
<PAGE>

required to place the Equipment in complete and running condition, and certified
as being eligible for the Sellers or the manufacturers generally available
maintenance contract ('Equipment Repair Notice. Lessee shall pay such invoiced
costs in addition to an inspection fee equal to one-tenth (.1 %) percent of the
applicable Equipment's cost as set forth In the applicable schedule ("Equipment
Inspection Fee"), within ten (10) days of the date of such notice. (4) In the
event Lessee fails to remit payment to Lessor within ten (10) days of receiving
such Equipment Repair Notice, Lessee shall pay to Lessor, Interim Rent equal to
the Daily Lease Rate Factor, multiplied by the Equipment cost as set forth In
the applicable Schedule, for each day in excess of the Master Lease Term, until
such Equipment Repair Notice payment is made.

(C) Purchase Option. Provided that no Event of Default has occurred and the
    ---------------
applicable Equipment Schedule has not been previously terminated, Lessee shall
have the right at its option, upon not less than 90 days and no more than 365
days written notice to Lessor prior to the Expiration Date, to purchase all (but
not less than all) of the Equipment subject to the applicable Schedule on its
Expiration Date. In such case, Lessee's purchase price shall be payable to
Lessor on the Expiration Date and shall be an amount equal to the Equipment's
fair market value as determined by Lessor In good with. Lessor shall transfer to
Lessee, "AS IS" "WHERE IS," without recourse or warranty, expressed or implied,
of any nature (except to warrant to those claiming by, under or through Lessee,
the absence of any liens created by Lessor), all of Lessor's right, title and
interest in and to the Items) of Equipment with respect to which such payment
has been received.

(D) Renewal Option. Provided that no Event of Default has occurred and the
    --------------
applicable lease Schedule has not been earlier terminated Lessee shall have the
right at its option, upon not less than ninety (90) days and no more than 365
days written notice to Lessor prior to the Expiration Date, to renew all (but
not less than all) of the Equipment subject to the applicable Equipment Schedule
for a first term renewal period not less than six months.

XII.  MISCELLANEOUS

(A) Captions: Counterparts: Integration: Entire Agreement. The captions
    -----------------------------------------------------
contained in the Master Lease are for convenience only and shall not affect the
interpretation of the Master Lease. The Master Lease and the Schedules may be
executed by the parties in one or more Counterparts, each of which shall be
deemed an original, but all of which shall constitute one and the same
agreement. Only one counterpart of the Master Lease and each Schedule shall be
marked "Original," and all other counterparts shall be marked "Duplicate." To
the extent, if any, that the Master Lease or any Schedule constitutes chattel
paper (as such term is defined in the Uniform Commercial Code in effect in any
applicable jurisdiction), no security interest in the Master Lease or any such
Schedule may be created through the transfer or possession of any counterpart
other than the Original. THIS AGREEMENT, TOGETHER WITH ALL SCHEDULES, ANNEXES
AND EXHIBITS THERETO, CONSTITUTES THE ENTIRE AGREEMENT OF THE PARTIES WITH
RESPECT TO THE SUBJECT MATTER HEREOF. NO VARIATION OR MODIFICATION OF THIS
AGREEMENT OR ANY WAIVER OF ANY OF ITS PROVISIONS OR CONDITIONS SHALL BE VALID
UNLESS IN WRITING AND SIGNED BY AN AUTHORIZED REPRESENTATIVE OF EACH OF THE
PARTIES HERETO.

                                 Page 12 of 15
<PAGE>

(B) Notices. All notices under the Master Lease and the Schedules shall be in
    -------
writing and shall be delivered to the parties by certified mail, return receipt
requested, by courier service or by facsimile transmission, at their respective
addresses or facsimile numbers set forth in the Schedules (or such other address
or number as either party may designate in writing from time to time). Notice
shall be deemed to have been given (1) on the third day after being deposited in
the United States mail, by certified mail, return receipt requested, properly
addressed and with postage prepaid; or (2) on the day delivered by courier
service or transmitted by facsimile.

(C) No Waiver: Lessor Approval. Any failure of Lessor to require strict
    --------------------------
performance by Lessee or any written waiver by Lessor of any provision of the
Master Lease or any Schedule shall not constitute consent to or waiver of any
other breach of the same or any other provision of the Master Lease or any
Schedule. The Master Lease and each Schedule shall not be binding upon Lessor
unless and until executed by Lessor.

(D) Governing Law: Severability. THE MASTER LEASE AND EACH SCHEDULE SHALL BE
    ---------------------------
GOVERNED BY THE INTERNAL LAWS (AS OPPOSED TO CONFLICTS OF LAW PROVISIONS) OF THE
STATE OF CALIFORNIA. If any provision of the Master Lease or any Schedule is
illegal, invalid or unenforceable under any applicable law of any jurisdiction,
such provision shall, as to such jurisdiction, be ineffective to the extent such
laws apply without invalidating the remaining provisions of the Master Lease or
such Schedule or causing such provision to be ineffective or unenforceable under
the laws of any other jurisdiction.

(E) Quiet Enjoyment. So long as no Event of Default has occurred and is
    ---------------
continuing, neither Lessor nor any Assignee will interfere with Lessee's quiet
enjoyment and use of the Equipment.

(F) Survival. All obligations of Lessee to make payments to Lessor under the
    --------
Master Lease or any Schedule or to indemnify Lessor pursuant to the terms of the
Master Lease or any Schedule, and all rights of Lessor under the Master Lease
and each Schedule shall survive the expiration or termination of the Master
Lease and each Schedule.

(G) Software. Any software or other licensed products attached to or provided in
    --------
connection with the Equipment shall at all times remain property of the owner
thereof, and Lessee shall not obtain title to any such software.

(H) Export Laws. Lessee shall not export or re-export , directly or indirectly,
    -----------
any software or technology received by It in connection with the Master Lease or
any Schedule, or allow the direct product thereof to be exported or re-exported,
directly or indirectly, in violation of applicable law, including without
limitation the regulations of the United States Department of Commerce.

(I) Present Value. In the event it is necessary to determine the present value
    -------------
of rentals under any Schedule, the parties agree that the discount rate to be
used in determining such present values shall be the then prevailing Federal
Reserve Bank Discount Rate as published in the Wall Street Journal as of the
date of discounting.

                                 Page 13 of 15
<PAGE>

(J) Foreign Corrupt Practices Act. The parties shall comply with all applicable
    -----------------------------
laws affecting this Agreement and the performance of this Agreement. The parties
shall maintain all registrations with governmental agencies, commercial
registries chambers of commerce, or other offices which may required under local
law in order to conduct their commercial business. The parties shall also comply
with United States laws applicable to the sale of the Equipment, including the
Foreign Corrupt Practices Act (which prohibits certain payments to governmental
officials or political parties).

(K) True Lease: Maximum Rate. The Master Lease and the Schedules are intended to
    ------------------------
be a "Finance Lease," as defined in Article 2A of the Uniform Commercial Code,
unless otherwise indicated in a Schedule. Lessor hereby informs Lessee that (1)
the identity of the Seller is set forth in the applicable Schedule, (2) the
Lessee is entitled under Article 2A to the promises and warranties, including
those of any third party, provided to Lessor in connection with, or as part of,
the contract by which Lessor acquired the Equipment, and (3) Lessee may
communicate with the Seller and receive an accurate and complete statement of
the promises and warranties, including any disclaimers and limitations of them
or of remedies. As a precaution in the event that, notwithstanding the express
intention of the parties hereto to enter into a true lease, the Master Lease or
any Schedule is ever deemed to be other than a true lease, or in the event that
the parties hereto intend to enter Into a lease intended as security, if so
indicated on the applicable Schedule, Lessee hereby grants Lessor a security
interest in the Equipment and all proceeds thereof, including, without
limitation, insurance proceeds. In any such event, notwithstanding any
provisions contained herein or in any Schedule, neither Lessor nor any Assignee
shall be entitled to receive, collect or apply as interest any amount in excess
of the maximum rate or amount permitted by applicable law. In the event Lessor
or any Assignee ever receives, collects or applies as interest any amount in
excess of the maximum amount permitted by applicable law, such excess amount.
shall be applied to the unpaid principal balance and any remaining excess
refunded to Lessee. In determining whether the interest paid or payable under
any specific contingency exceeds the maximum rate or amount permitted by
applicable law, Lessor and Lessee shall, to the maximum extent permitted under
applicable law, characterize any non principal payment as an expense or fee
rather than intent, exclude voluntary prepayments and the effect thereof, and
spread the total amount of interest over the entire term of the Master Lease and
the Schedules.

(L) Waiver of Jury Trial. Etc. The Lessee and the Lessor each hereby waives any
    -------------------------
right to trial by jury in any litigation in any Court with respect to, in
connection with, or arising out of the Master Lease or any schedule entered into
in connection therewith, or any other claim or dispute howsoever arising,
between the Lessor and the Lessee.

                                 Page 14 of 15
<PAGE>

LESSEE, BY THE SIGNATURE BELOW OF ITS AUTHORIZED REPRESENTATIVE, ACKNOWLEDGES
THAT IT HAS READ THE MASTER LEASE, UNDERSTANDS IT, AND AGREES TO BE BOUND BY ITS
TERMS AND CONDITIONS.

LESSOR:    IMPERIAL BANK EQUIPMENT          LESSEE:    Chorum Technologies, Inc.
           LEASING DIVISION,
           A Division of Imperial Bank

Signature: _________________________        Signature:  /s/  Bob Trecartin
                                                       -------------------------

Name:      _________________________        Name:      Bob Trecartin

Title:     _________________________        Title:     VP Finance

                                 Page 15 of 15
<PAGE>

IMPERIAL BANK EQUIPMENT LEASING DIVISION,                       Amendment A
A division of Imperial Bank

     THIS AMENDMENT "A" dated July 7, 2000, to Master Lease Agreement dated July
7, 2000, (the "Agreement"), is entered into by and between IMPERIAL BANK
EQUIPMENT LEASING DIVISION, a division of Imperial Bank, a California
corporation and Chorum Technologies, Inc., a corporation. Capitalized terms used
herein and not otherwise defined shall have the meanings set forth in the
Agreement.

1.   The Agreement is hereby amended as follows:

MASTER LEASE AGREEMENT:
     IV.    RENT
            (A) Rent - Line 4. - Delete section between "at the address" and
                ----
                "Lessor" and amend to read "at the Lessor's address or as
                otherwise directed by Lessor."

     VIII.  LESSEE'S REPRESENTATIONS, WARRANTIES AND CONVENANTS
            (F) Further Assurances; Payment of Lessor's Expenses.
                ------------------------------------------------
                Line 4 - Between "reasonable" and "costs" insert "incremental
                         outside direct"
                Line 5 - Delete "or interpretation"
                Line 6 - Between "Schedule and ";" insert "during the existence
                         of any Event of Default"

            (G) Notification.
                ------------
                Line 1 - Between "within" and "days" replace "10" with "20"

     IX.    GENERAL INDEMNITY
            Line 11(B) - Between "HAVE" and "DAYS" replace "THIRTY (30)" with
                         "SIXTY (60)"

     X.     LESSOR'S RIGHTS
            (A)  Assignment.
                 ----------
                 Line 1 -  After "Assignment," Insert "At any time after funding
                                  ----------
                           with respect to any schedule.
                 Line 3 -  After "Assignee")" Insert "with a limit of three
                           Assignees other than Imperial Bank Equipment Leasing
                           Division."

     XI.    DEFAULTS AND REMEDIES
            (A)  Events of Default.
                 -----------------
                 (1) Line 2 - Replace "the time period set forth in a schedule"
                              with "ten (10) days of the date due"
                 (2)  Line 3 - Delete "or any other party"
<PAGE>

                             APPENDIX A- CONTINED

          XII.   END OF LEASE TERM
                 (B) Return.
                     ------
                    (1)  Line 2 - Between "Lessor" and "all" insert "any or"
                         Line 2 - Between "all": and "of" delete ",(but not less
                         than all),"
                    (1)  (b)  Line 8 - Replace "120 days" with "60 days"
                    (2)  Line 9 - Between "returned" and "to" insert "or paid
                         for"
                    (3)  Line 17 - Replace "one-tenth (.1%)" with "one-twentieth
                         .05%"
                 (C) Purchase Option.
                     ---------------
                         Line 1 - Between "occurred" and "and" insert "and has
                                  not been cured"
                         Line 3 - Between "purchase" and "all" insert "any or"
                         Line 3 - Between "all" and "of" delete "(but not less
                                  than all),"
                    "occurred" and "and" insert "and has not been cured"
                 (D) Renewal Option.
                     ---------------
                         Line 1 - Between "occured"
                         Line 2 - Between "renew" and "all" insert "any or"
                         Line 3 - Between "all" and "of" delete "(but not less
                                  than all)"

          XII MISCELLANEOUS

                    (1)  Line 2 - Delete verbiage between "prevailing" and
                                  "discounting" and replace with "prime rate of
                                  Imperial Bank."

SCHEDULE "B" TO EQUIPMENT SCHEDULE 001:
Paragraph 1 - Line 2 - Delete "all, (but not less than all)," replace with "any
or all"
              Line 2 - Between "subject" and Schedule" insert "to this"
              Line 9 - Replace "120 days" with "60 days"

Paragraph 3 - Line 5 - Replace "one-tenth (.1%)" with "one-twentieth (.05%)"
              Line 7 - Replace "ten (10)" with "thirty (30)"

2.   Except as specifically set forth herein, all of the terms and provisions of
the Agreement are ratified and confirmed by the parties hereto and shall remain
in full force and effect.

3.   This Amendment shall be governed by, construed and interpreted in
accordance with the internal laws (and not the law of conflicts) of the state of
California.

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed by their authorized representatives the day and year first above
written.

IMPERIAL BANK EQUIPMENT LEASING DIVISION, Chorum Technologies, Inc. A division
of Imperial Bank

By:  _______________________________________           By: /s/ Bob Trecatin
                                                           _____________________

Its: ______________________________________            Its: VP Finance

                                       2
<PAGE>

                               SCHEDULE NO. 001
                           Dated as of July 7, 2000
                                  Lessee 848
              A Schedule Made Pursuant to Master Lease Agreement
                           Dated as of July 7, 2000,
               Between Imperial Bank Equipment Leasing Division,
                    a division of Imperial Bank, as Lessor,
                    and Chorum Technologies, Inc., as Lessee

     The terms and conditions of this Schedule incorporate the terms and
     conditions of the Master Lease Agreement identified above. Capitalized
     terms not defined in this Schedule shall have the meanings assigned to them
     in the Master Lease Agreement.

     I.   EQUIPMENT

     The Equipment covered by this Schedule is described on Schedule A,
     attached.

     II.  ADDRESSES FOR LESSEE AND LESSOR:

     (A) Lessee's Address(es):
         --------------------
         (1) Chief Executive Office Address:        1303 E. Arapaho Road
                                                    Richardson, TX  75081-2444

         (2) Lessee's Address to Receive Invoices:  Attention:  Accounts Payable
                                                    1303 E. Arapaho Road
                                                    Richardson, TX  75081-2444

             Contact Name:                          Bob Trecartin
             Contact Phone Number:                  214-570-3517
             Contact Facsimile Number:              214-575-6237

         (3) Lessee's Address to Receive Notices:   Same

             Contact Name:                          Same
             Contact Phone Number:
             Contact Facsimile Number:

     (B) Lessor's Addresses:
         ------------------
        (1) Chief Executive Office:                 Imperial Bank Equipment
                                                    Leasing Division 9920 South
                                                    La Cienega Boulevard 12th
                                                    Floor Inglewood, CA 90301
<PAGE>

     (2) Address for Payments:       Imperial Bank Equipment Leasing Division
                                     Payment Processing 9920 South La Cienega
                                     Boulevard 12/th/ Floor Inglewood, CA 90301

III.  FINANCIAL TERMS

(A) Equipment Acquisition Cost:      $10,000,000.00 (maximum of 25% for software
                                     and soft costs with the hardware portion on
                                     a per schedule basis not to exceed 20% for
                                     information technology equipment) With 50%
                                     equipment leased no later than December 31,
                                     2000.

(B) Equipment Location:              1301 E. Arapaho Road
                                     Richardson, TX 75081-2444

(C) Initial Term (number of months): 48 Months

(D) Initial Term Commencement Date:  1st day of the month following Acceptance
                                     Date

(E) Lessee's Federal Tax ID:         84-1431727

(F) Lease Rate Factor:               2.4140%

(G) Acceptance Date:                 TBD

(H) Seller:                          Various Vendors

(I) Purchase Option:                 Fair Market Value not to exceed 15% of
                                     Original Acquisition Cost.

(J) Documentation Fee:               $250.00. Legal documentation to be
                                     performed by Imperial Bank attorneys.
IV. RENT AND TERM

(A) Rent:                            On a per Schedule basis, monthly rent will
                                     be based upon the Lease Rate Factor(s)
                                     multiplied by the Equipment Acquisition
                                     Cost plus applicable tax

(B) Due with Documentation:          $250.00

                                       2
<PAGE>

(C) Rent Due Date:                     1st of the month

(D) Rent past due after:               10 days

(E) Late Charge:                       1.5% of the current amount(s) due
  (Not to exceed maximum rate
   permitted by applicable law)

(F) Rental Period:                     Monthly in advance

(G) Required Notice                    No less than 90 days or no more than 365
                                       days prior to Lease Termination

LESSEE, BY THE SIGNATURE BELOW OF ITS AUTHORIZED REPRESENTATIVE, ACKNOWLEDGES
THAT IT HAS READ THIS LEASE, UNDERSTANDS IT, AND AGREES TO BE BOUND BY ITS TERMS
AND CONDITIONS.

LESSOR: IMPERIAL LEASING               LESSEE: CHORUM TECHNOLOGIES,
        A Division of Imperial Bank            INC.

Signature: ________________________    Signature:  /s/  Bob Trecartin
                                                   ----------------------------

Name:      ________________________    Name:       Bob Trecartin

Title:     ________________________    Title:      VP Finance

                                       3
<PAGE>

                                  SCHEDULE"A"
                         TO EQUIPMENT SCHEDULE NO. 001
                           TO MASTER LEASE AGREEMENT
                           DATED AS OF JULY 7, 2000
               BETWEEN IMPERIAL BANK EQUIPMENT LEASING DIVISION,
                    A DIVISION OF IMPERIAL BANK, AS LESSOR,
                   AND CHORUM TECHNOLOGIES, INC., AS LESSEE

                                EQUIPMENT LIST

Equipment Description                                  Quantity  Estimated Cost
---------------------                                  --------  --------------

Computer hardware to include servers, desktop PC's,              $10,000,000.00
notebook, computers, computer peripherals, telecom gear,
test equipment, manufacturing machinery and equipment,
furniture and other miscellaneous equipment.

Up to 25% of the lease line may be used for software and
soft costs. The hardware portion on a per schedule basis
shall not exceed 20% for information technology equipment.
50% of the lease line to be used no later than December 31,
2000.

Additionally, up to $2,500,000.00 of the lease line will be
available for sale/leaseback of equipment not more than 90
days in use.

                                                                 $10,000,000.00
<PAGE>

Lessor Initials:____________________    Lessee Initials:  /s/  BT
                                                          --------------------

                                  SCHEDULE"B"
                         TO EQUIPMENT SCHEDULE NO. 001
                   TO MASTER LEASE AGREEM THE "MASTER LEASE")
                            DATED AS OF MAY 5, 2000
        BETWEEN IMPERIAL BANK EQUIPMENT LEASING DIVISION, A DIVISION OF
                           IMPERIAL BANK, AS LESSOR,
                    AND CHORUM TECHNOLOGIES, INC., AS LESSEE

                          EQUIPMENT RETURN PROVISIONS

Upon the expiration or other permitted termination of this Schedule or any
extension thereof, Lessee, at its sole cost, risk, and expense, will return to
Lessor all, (but not less than all), of the Equipment then subject Schedule to a
location in the continental United States specified by Lessor. Lessee shall be
responsible at its sole cost and expense, for (a) the de-installation, removal
and packaging of the Equipment (including, but not limited to, any and all
applicable software, all manuals, maintenance records, maintenance record
jackets, repair orders and all other similar documents) in a manner suitable for
cartage by a common commercial carrier acceptable to Lessor, and (b) the
transportation of the Equipment, upon written notification by Lessor, as to the
date and destination of the shipping. Such Equipment, upon return, shall be free
and clear of all mortgages, liens, security interest, charges, encumbrances and
claims. If Lessor shall so require, Lessee shall provide free and safe storage,
as well as maintain sufficient insurance coverage (as specified in the Master
Lease) for such Equipment for a period not to exceed 120 days from the
expiration date or the last day of any extension period therefor.

Upon return of such Equipment, Lessor or its agent shall inspect the Equipment.
If any item of Equipment is not returned to Lessor, it shall be deemed to be a
casualty and an Event of Loss during the Lease Term. In the event Lessor
determines that repairs, additions or replacements are necessary to place the
Equipment in the same condition as when originally leased to Lessee (reasonable
wear and tear excepted), which at a minimum will require that the Equipment be
in complete and running condition with no missing or damaged components and
certified as being eligible for the Seller's or the manufacturer's generally
available maintenance contract at then prevailing prices.

If Lessor determines that the Equipment (after inspection) is damaged or worn
beyond normal wear and tear, Lessor or Lessor's agent will prepare an Equipment
Repair Notice ("ERN") which fully describes the repairs and the estimated cost
required to place the Equipment in complete and running condition, and certified
as being eligible for the Seller's or the manufactures generally available
maintenance contract Lessee shall pay such invoiced costs which shall include an
Equipment Inspection Fee equal to one-tenth (.1%) percent of the applicable
Equipment Schedule's "first cost," within ten (10) days of the date of the
Equipment Repair Notice. In the event Lessee fails to remit payment to Lessor
within ten (10) days of receiving such Equipment Repair Notice, Lessee shall pay
to Lessor, interim Rent equal to the Daily Lease Rate Factor, multiplied by the
Equipment Cost as specified in the applicable Schedule, for each day in excess
of Lease Term of the applicable Equipment Schedule, until such payment is made.

Lessor Initials:____________________    Lessee Initials:  /s/ BT

                                                          ---------------------
<PAGE>

Lessor Initials:____________________    Lessee Initials:  /s/ BT
                                                          ---------------------

At the time of return, the Equipment shall be (I) in compliance with all
applicable federal, state and local laws; and (II) free of all advertising or
insignia thereon by Lessee.

Hold Harmless. Lessee agrees that Lessor will be held harmless for any damages
---------------
to disassembly site if Lessee or Lessee's agent causes disassembly.

Insurance on Equipment during return. Lessee will obtain and pay for a policy of
------------------------------------
transit insurance for the delivery period in an amount equal to the higher of
Replacement Value or Casualty Value of the Equipment and Lessor shall be named
as loss payee on such policies.

Any further Return Instructions more specifically related to the Equipment (if
applicable) shall be attached as Exhibit "C" Additional Return Provisions.

Lessor Initials:____________________    Lessee Initials:  /s/ BT
                                                          ---------------------
                                       2
<PAGE>

                            INSURANCE AUTHORIZATION

                                                      LEASE DATED:  July 7, 2000

LESSOR:     IMPERIAL BANK EQUIPMENT LEASING DIVISION
            a division of Imperial Bank
ADDRESS:    9920 South La Cienega Boulevard, Inglewood, California 90301
LESSEE:     Chorum Technologies, Inc.
ADDRESS:    1303 E. Arapaho Road, Richardson, TX 75081-2444

EQUIPMENT INFORMATION
NO. of ITEMS   DESCRIPTION OF EQUIPMENT (Model, Serial No. etc.)  ESTIMATED COST
                                                                  $10,000,000.00
 Refer to attached Schedule "A"                                   $
                                                                  $
                                                             TAX  $
EQUIPMENT LOCATION Address (Include County)      I ADDITIONAL AMOUNTS (Describe)
1303 E. Arapaho Road, Richardson, TX 75081-2444  I                $
                                                 I                $
                                          TOTAL ESTIMATED COST    $10,000,000.00

TO:  INSURANCE AGENT OR BROKER

     We are entering into an Equipment Lease or Lease and Security Agreement to
Master Lease Agreement with Imperial Bank Equipment Leasing Division, a division
of Imperial Bank ("Lessor") for the equipment described above ("Equipment").
The Lease requires us to carry physical damage and third party liability
insurance on the Equipment as described below.

     Please arrange this insurance for our account with insurance companies
rated A or better by A.M. Best Company and immediately send a certificate of
insurance or binder specifically describing all required amounts and
endorsements to:

     IMPERIAL BANK EQUIPMENT LEASING DIVISION, A division of Imperial Bank
   9920 South La Cienega Boulevard, 12th Floor, Inglewood, California 90301
                               Attn: Operations

I.   PHYSICAL DAMAGE INSURANCE

     A.   All Risks coverage (including earthquake and flood) for the Equipment
in an amount equal to its Total Estimated Cost (to be adjusted to its actual
Total Cost after the Acceptance Date).

     B.   Endorsements (1) naming Lessor as an additional insured and loss payee
with respect to the Equipment, (2) providing 30 days' written notice to Lessor
before coverage lapses or is cancelled or materially changed, and (3) providing
that such coverage shall not be rescinded, impaired or invalidated by any act or
neglect of Lessee.
<PAGE>

II.  THIRD PARTY LIABILITY INSURANCE

     A.   $1,000,000 combined single limit bodily injury and property damage
coverage.

     B.   Endorsements (1) naming Lessor as an additional insured with respect
to the Equipment, (2) providing that such coverage is primary as to the
Equipment without right of contribution from any other insurance, (3) providing
30 days' prior written notice to Lessor before coverage lapses or is cancelled
or materially changed, and (4) providing that such coverage shall not be
rescinded, impaired or invalidated by any act or neglect of Lessee.

Very truly yours,            Agent's Name, Address, City State , Zip, Phone

Chorum Technologies, Inc.    Brock Duckworth, Sr. VP, Aon Risk Services of Texas
-------------------------    ---------------------------------------------------
PRINT LESSEE'S NAME ABOVE    AGENT'S NAME

                             City Place Center East - Suite 800
                             ---------------------------------------------
                             ADDRESS

By:  /s/  Bob Trecartin      2711 N. Haskell Avenue, Dallas, Texas  75204
     ------------------      ---------------------------------------------
                             ADDRESS

Printed Name: Bob Trecartin  Attn:  Nola Brown
                                    --------------------------------------

Title:  VP Finance           Phone:   214-989-2368
                                      ------------------------------------

                                       2
<PAGE>

                                  CERTIFICATE
                         CORPORATE LEASING RESOLUTION

I, Kent Coker, do hereby certify that I am the duly elected and qualified
Secretary of Chorum Technologies, Inc. a Delaware corporation; that the
following is a true and correct copy of resolutions duly adopted by the Board of
Directors of said corporation at a meeting of said Board of Directors convened
and held in accordance with the By-Laws of said corporation on the 10th day of
May, 2000, and that said resolutions are now in full force and effect:

          "RESOLVED: That any officer of this corporation be and is hereby
          authorized, directed and empowered to negotiate, execute and deliver
          on behalf of this corporation a lease agreement with IMPERIAL BANK
          EQUIPMENT LEASING DIVISION, division of Imperial Bank (Lessor),
          whereby this corporation will lease Computer hardware to include
                                              ----------------------------
          servers, desktop PC's, notebook, Computers, computer peripherals,
          ----------------------------------------------------------------
          telecom gear, test equipment, furniture and other miscellaneous
          ---------------------------------------------------------------
          equipment on terms and conditions which shall be determined by said
          ---------
          officer to be advisable and in the best interest of this corporation
          and the execution of such lease agreement by said officer shall be
          conclusive evidence of the approval thereof.

          FURTHER RESOLVED: That the Secretary be and is hereby authorized to
          furnish to IMPERIAL BANK EQUIPMENT LEASING DIVISION, division of
          Imperial Bank a certified copy of these resolutions."

          I FURTHER CERTIFY that said resolutions are still in full force and
          effect and have not been amended or revoked.

     IN WITNESS WHEREOF, I have affixed my name as Secretary of said corporation
and have caused the corporate seal of said corporation to be hereunto affixed
this ______ day of ____________________, 2000.

                                                 /s/ Kent Coker
                                                 ------------------------------
                                                                     Secretary<PAGE>

                                                                    EXHIBIT 10.9

                            MASTER LEASE AGREEMENT

MASTER LEASE AGREEMENT (the "Master Lease") dated September 22, 1998 by and
between COMDISCO, INC. ("Lessor") and CHORUM TECHNOLOGIES, INC. ("Lessee").

IN CONSIDERATION of the mutual agreements described below, the parties agree as
follows (all capitalized terms are defined in Section 14.18):

1.  Property Leased.

Lessor leases to Lessee all of the Equipment described on each Summary Equipment
Schedule. In the event of a conflict, the terms of the applicable Schedule
prevail over this Master Lease.

2.  Term.

On the Commencement Date, Lessee will be deemed to accept the Equipment, will be
bound to its rental obligations for each item of Equipment and the term of a
Summary Equipment Schedule will begin and continue through the Initial Term and
thereafter until terminated by either party upon prior written notice received
during the Notice Period. No termination may be effective prior to the
expiration of the Initial Term.

3.  Rent and Payment.

Rent is due and payable in advance on the first day of each Rent Interval at the
address specified in Lessor's invoice. Interim Rent is due and payable when
invoiced. If any payment is not made when due, Lessee will pay a Late Charge on
the overdue amount. Upon Lessee's execution of each Schedule, Lessee will pay
Lessor the Advance specified on the Schedule. The Advance will be credited
towards the final Rent payment if Lessee is not then in default. No interest
will be paid on the Advance.

4.  Selection; Warranty and Disclaimer of Warranties.

4.1 Selection. Lessee acknowledges that it has selected the Equipment and
disclaims any reliance upon statements made by the Lessor, other than as set
forth in the Schedule.

4.2 Warranty and Disclaimer of Warranties. Lessor warrants to Lessee that, so
long as Lessee is not in default, Lessor will not disturb Lessee's quiet and
peaceful possession, and unrestricted use of the Equipment. To the extent
permitted by the manufacturer, Lessor assigns to Lessee during the term of the
Summary Equipment Schedule any manufacturer's warranties for the Equipment.
LESSOR MAKES NO OTHER WARRANTY, EXPRESS OR IMPLIED AS TO ANY MATTER WHATSOEVER,
INCLUDING, WITHOUT LIMITATION, THE MERCHANTABILITY OF THE EQUIPMENT OR ITS
FITNESS FOR A PARTICULAR PURPOSE. Lessor is not responsible for any liability,
claim, loss, damage or expense of any kind (including strict liability in tort)
caused by the Equipment except for any loss or damage caused by the willful
misconduct or negligent acts of Lessor. In no event is Lessor responsible for
special, incidental or consequential damages.

5.  Title; Relocation or Sublease; and Assignment.

5.1 Title. Lessee holds the Equipment subject and subordinate to the rights of
the Owner, Lessor, any Assignee and any Secured Party. Lessee authorizes Lessor,
as Lessee's agent, and at Lessor's expense, to prepare, execute and file in
Lessee's name precautionary Uniform Commercial Code financing statements showing
the interest of the Owner, Lessor, and any Assignee or Secured Party in the
Equipment and to insert serial numbers in Summary Equipment Schedules as
appropriate. Lessee will, at its expense, keep the Equipment free and clear from
any liens or encumbrances of any kind (except any caused by Lessor) and will
indemnify and hold the Owner, Lessor, any Assignee and Secured Party harmless
from and against any loss caused by Lessee's failure to do so, except where such
is caused by Lessor.

5.2 Relocation or Sublease. Upon prior written notice, Lessee may relocate
Equipment to any location within the continental United States provided (i) the
Equipment will not be used by an entity exempt from federal income tax, and (ii)
all additional costs (including any administrative fees, additional taxes and
insurance coverage) are reconciled and promptly paid by Lessee.

Lessee may sublease the Equipment upon the reasonable consent of the Lessor and
the Secured Party. Such consent to sublease will be granted if: (i) Lessee meets
the relocation requirements set out above. (ii) the sublease is expressly
subject and subordinate to the terms of the Schedule, (iii) Lessee assigns its
rights in the sublease to Lessor and the Secured Party as additional collateral
and security, (iv) Lessee's obligation to maintain and insure the Equipment is
not altered, (v) all financing statements required to continue the Secured
Party's prior perfected security interest are filed, and (vi) Lessee executes
sublease documents acceptable to Lessor.

No relocation or sublease will relieve Lessee from any of its obligations under
this Master Lease and the relevant Schedule.

5.3 Assignment by Lessor. The terms and conditions of each Schedule have been
fixed by Lessor in order to permit Lessor to sell and/or assign or transfer its
interest or grant a security interest in each Schedule and/or the Equipment to a
Secured Party or Assignee. In that event, the term Lessor will mean the Assignee
and any Secured Party. However, any assignment, sale, or other transfer by
Lessor will not relieve Lessor of its obligations to Lessee and will not
materially change Lessee's duties or materially increase the burdens or risks
imposed on Lessee. The Lessee consents to and will acknowledge such assignments
in a written notice given to Lessee. Lessee also agrees that:

(a)     The Secured Party will be entitled to exercise all of Lessor's rights,
but will not be obligated to perform any of the obligations of Lessor. The
Secured Party will not disturb Lessee's quiet and peaceful possession and
unrestricted use of the Equipment so long as Lessee is not in default and the
Secured Party continues to receive all Rent payable under the Schedule; and

(b)     Lessee will pay all Rent and all other amounts payable to the Secured
Party, despite any defense or claim which it has against Lessor. Lessee reserves
its right to have recourse directly against Lessor for any defense or claim;

(c)     Subject to and without impairment of Lessee's leasehold rights in the
Equipment, Lessee holds the Equipment for the Secured Party to the extent of the
Secured Party's rights in that Equipment.

6.  Net Lease; Taxes and Fees.

6.1 Net Lease. Each Summary Equipment Schedule constitutes a net lease. Lessee's
obligation to pay Rent and all other amounts due hereunder is absolute and
unconditional and is not subject to any abatement, reduction, set-off, defense,
counterclaim, interruption, deferment or recoupment for any reason whatsoever.

6.2 Taxes and Fees. Lessee will pay when due or reimburse Lessor for all taxes,
fees or any other charges (together with any related interest or penalties not
arising from the negligence of Lessor) accrued for or arising during the term of
each Summary Equipment Schedule against Lessor, Lessee or the Equipment by any
governmental authority (except only Federal, state, local and franchise taxes on
the capital or the net income of Lessor). Lessor will file all personal property
tax returns for the Equipment and pay all such property taxes due. Lessee will
reimburse Lessor for property taxes within thirty (30) days of receipt of an
invoice.

7.  Care, Use and Maintenance; Inspection by Lessor.

7.1 Care, Use and Maintenance. Lessee will maintain the Equipment in good
operating order and appearance, protect the Equipment from deterioration, other
than normal wear and tear, and will not use the Equipment for any purpose other
than that for which it was designed. If commercially available and considered
common business practice for each item of Equipment, Lessee will maintain in
force a standard maintenance contract with the manufacturer of the Equipment, or
another party acceptable to Lessor, and will provide Lessor with a complete copy
of that contract. If Lessee has the Equipment maintained by a party other than
the manufacturer or self maintains, Lessee agrees to pay any costs necessary for
the manufacturer to bring the Equipment to then current release, revision and
engineering change levels, and to re-certify the Equipment as eligible for
manufacturer's maintenance at the expiration of the lease term, provided re-
certification is available and is required by Lessor. The lease term will
continue upon the same terms and conditions until recertification has been
obtained.

7.2 Inspection by Lessor. Upon reasonable advance notice, Lessee, during
reasonable business hours and subject to Lessee's security requirements, will
make the Equipment and its related log and maintenance records available to
Lessor for inspection.

8.  Representations and Warranties of Lessee. Lessee hereby represents, warrants
and covenants that with respect to the Master Lease and each Schedule executed
hereunder:

(a)     The Lessee is a corporation duly organized and validly existing in good
standing under the taws of the jurisdiction of its incorporation, is duly
qualified to do business in each jurisdiction (including the jurisdiction where
the Equipment is, or is to be, located) where its ownership or lease of property
or the conduct of its business requires such qualification, except for where
such lack of qualification would not have a material adverse effect on the
Company's business; and has full corporate power and authority to hold property
under the Master Lease and each Schedule and to enter into and perform its
obligations under the Master Lease and each Schedule.

(b)     The execution and delivery by the Lessee of the Master Lease and each
Schedule and its performance thereunder have been duly authorized by all
necessary corporate action on the part of the Lessee, and the Master Lease and
each Schedule are not inconsistent with the Lessee's Articles of Incorporation
or Bylaws, do not
<PAGE>

contravene any law or governmental rule, regulation or order applicable to it,
do not and will not contravene any provision of, or constitute a default under,
any indenture, mortgage, contract or other instrument to which it is a party or
by which it is bound, and the Master Lease and each Schedule constitute legal,
valid and binding agreements of the Lessee, enforceable in accordance with their
terms, subject to the effect of applicable bankruptcy and other similar laws
affecting the rights of creditors generally and rules of law concerning
equitable remedies.

(c)     There are no actions, suits, proceedings or patent claims pending or, to
the knowledge of the Lessee, threatened against or affecting the Lessee in any
court or before any governmental commission, board or authority which, if
adversely determined, will have a material adverse effect on the ability of the
Lessee to perform its obligations under the Master Lease and each Schedule.

(d)     The Equipment is personal property and when subjected to use by the
Lessee will not be or become fixtures under applicable law.

(e)     The Lessee has no material liabilities or obligations, absolute or
contingent (individually or in the aggregate), except the liabilities and
obligations of the Lessee as set forth in the Financial Statements and
liabilities and obligations which have occurred in the ordinary course of
business, and which have not been, in any case or in the aggregate, materially
adverse to Lessee's ongoing business.

(f)      To the best of the Lessee's knowledge, the Lessee owns, possesses, has
access to, or can become licensed on reasonable terms under all patents, patent
applications, trademarks, trade names, inventions, franchises, licenses,
permits, computer software and copyrights necessary for the operations of its
business as now conducted, with no known infringement of, or conflict with, the
rights of others.

(g)     All material contracts, agreements and instruments to which the Lessee
is a party are in full force and effect in all material respects, and are valid,
binding and enforceable by the Lessee in accordance with their respective terms,
subject to the effect of applicable bankruptcy and other similar laws affecting
the rights of creditors generally, and rules of law concerning equitable
remedies.

9.   Delivery and Return of Equipment.

Lessee hereby assumes the full expense of transportation and in-transit
insurance to Lessee's premises and installation thereat of the Equipment. Upon
termination (by expiration or otherwise) of each Summary Equipment Schedule,
Lessee shall, pursuant to Lessor's instructions and at Lessee's full expense
(including, without limitation, expenses of transportation and in-transit
insurance), return the Equipment to Lessor in the same operating order, repair,
condition and appearance as when received, less normal depreciation and wear and
tear. Lessee shall return the Equipment to Lessor at 6111 North River Road,
Rosemont, Illinois 60018 or at such other address within the continental United
States as directed by Lessor, provided, however, that Lessee's expense shall be
limited to the cost of returning the Equipment to Lessor's address as set forth
herein. During the period subsequent to receipt of a notice under Section 2,
Lessor may demonstrate the Equipment's operation in place and Lessee will supply
any of its personnel as may reasonably be required to assist in the
demonstrations.

10.  Labeling.

Upon request, Lessee will mark the Equipment indicating Lessor's interest with
labels provided by Lessor. Lessee will keep all Equipment free from any other
marking or labeling which might be interpreted as a claim of ownership.

11.  Indemnity.

With regard to bodily injury and property damage liability only, Lessee will
indemnify and hold Lessor, any Assignee and any Secured Party harmless from and
against any and all claims, costs, expenses, damages and liabilities, including
reasonable attorneys' fees, arising out of the ownership (for strict liability
in tort only), selection, possession, leasing, operation, control, use,
maintenance, delivery, return or other disposition of the Equipment during the
term of this Master Lease or until Lessee's obligations under the Master Lease
terminate. However, Lessee is not responsible to a party indemnified hereunder
for any claims, costs, expenses, damages and liabilities occasioned by the
negligent acts of such indemnified party. Lessee agrees to carry bodily injury
and property damage liability insurance during the term of the Master Lease in
amounts and against risks customarily insured against by the Lessee on equipment
owned by it. Any amounts received by Lessor under that insurance will be
credited against Lessee's obligations under this Section.

12.  Risk of Loss.

Effective upon delivery and until the Equipment is returned, Lessee relieves
Lessor of responsibility for all risks of physical damage to or loss or
destruction of the Equipment. Lessee will carry casualty insurance for each item
of Equipment in an amount not less than the Casualty Value. All policies for
such insurance will name the Lessor and any Secured Party as additional insured
and as loss payee, and will provide for at least thirty (30) days prior written
notice to the Lessor of cancellation or expiration, and will insure Lessor's
interests regardless of any breach or violation by Lessee of any representation,
warranty or condition contained in such policies and will be primary without
right of contribution from any insurance effected by Lessor. Upon the execution
of any Schedule, the Lessee will furnish appropriate evidence of such insurance
acceptable to Lessor.

Lessee will promptly repair any damaged item of Equipment unless such Equipment
has suffered a Casualty Loss. Within fifteen (15) days of a Casualty Loss,
Lessee will provide written notice of that loss to Lessor and Lessee will, at
Lessee's option, either (a) replace the item of Equipment with Like Equipment
and marketable title to the Like Equipment will automatically vest in Lessor or
(b) pay the Casualty Value and after that payment and the payment of all other
amounts due and owing with respect to that item of Equipment, Lessee's
obligation to pay further Rent for the item of Equipment will cease.

13.  Default, Remedies and Mitigation.

13.1 Default. The occurrence of any one or more of the following Events of
Default constitutes a default under a Summary Equipment Schedule:

(a)     Lessee's failure to pay Rent or other amounts payable by Lessee when due
if that failure continues for five (5) business days after written notice; or

(b)     Lessee's failure to perform any other term or condition of the Schedule
or the material inaccuracy of any representation or warranty made by the Lessee
in the Schedule or in any document or certificate furnished to the Lessor
hereunder if that failure or inaccuracy continues for ten (10) business days
after written notice; or

(c)     An assignment by Lessee for the benefit of its creditors, the failure by
Lessee to pay its debts when due, the insolvency of Lessee, the filing by Lessee
or the filing against Lessee of any petition under any bankruptcy or insolvency
law or for the appointment of a trustee or other officer with similar powers,
the adjudication of Lessee as insolvent, the liquidation of Lessee, or the
taking of any action for the purpose of the foregoing; or

(d)     The occurrence of an Event of Default under any Schedule, Summary
Equipment Schedule or other agreement between Lessee and Lessor or its Assignee
or Secured Party.

13.2  Remedies. Upon the occurrence of any of the above Events of Default,
Lessor, at its option, may:

(a)     enforce Lessee's performance of the provisions of the applicable
Schedule by appropriate court action in law or in equity;

(b)     recover from Lessee any damages and or expenses, including Default
Costs;

(c)     with notice and demand, recover all sums due and accelerate and recover
the present value of the remaining payment stream of all Rent due under the
defaulted Schedule (discounted at the same rate of interest at which such
defaulted Schedule was discounted with a Secured Party plus any prepayment fees
charged to Lessor by the Secured Party or, if there is no Secured Party, then
discounted at 6%) together with all Rent and other amounts currently due as
liquidated damages and not as a penalty;

(d)     with notice and process of law and in compliance with Lessee's security
requirements, Lessor may enter on Lessee's premises to remove and repossess the
Equipment without being liable to Lessee for damages due to the repossession,
except those resulting from Lessor's, its assignees', agents' or
representatives' negligence; and

(e)     pursue any other remedy permitted by law or equity.

The above remedies, in Lessor's discretion and to the extent permitted by law,
are cumulative and may be exercised successively or concurrently.

13.3 Mitigation. Upon return of the Equipment pursuant to the terms of Section
13.2, Lessor will use its best efforts in accordance with its normal business
procedures (and without obligation to give any priority to such Equipment) to
mitigate Lessor's damages as described below. EXCEPT AS SET FORTH IN THIS
SECTION, LESSEE HEREBY WAIVES ANY RIGHTS NOW OR HEREAFTER CONFERRED BY STATUTE
OR OTHERWISE WHICH MAY REQUIRE LESSOR TO MITIGATE ITS DAMAGES OR MODIFY ANY OF
LESSOR'S RIGHTS OR REMEDIES STATED HEREIN. Lessor may sell, lease or otherwise
dispose of all or any part of the Equipment at a public or private sale for cash
or credit with the privilege of purchasing the Equipment. The proceeds from any
sale, lease or other disposition of the Equipment are defined as either:

(a)     if sold or otherwise disposed of, the cash proceeds less the Fair Market
Value of the Equipment at the expiration of the Initial Term less the Default
Costs; or
<PAGE>

(b)     if leased, the present value (discounted at three percent (3%) over the
U.S. Treasury Notes of comparable maturity to the term of the re-lease) of the
rentals for a term not to exceed the Initial Term, less the Default Costs.

Any proceeds will be applied against liquidated damages and any other sums due
to Lessor from Lessee. However, Lessee is liable to Lessor for, and Lessor may
recover, the amount by which the proceeds are less than the liquidated damages
and other sums due to Lessor from Lessee.

14.   Additional Provisions.

14.1  Board Attendance. Upon invitation of Lessee, one representative of Lessor
will have the right to attend Lessee's corporate Board of Directors meetings and
Lessee will give Lessor reasonable notice in advance of any special Board of
Directors meeting, which notice will provide an agenda of the subject matter to
be discussed at such board meeting. Lessee will provide Lessor with a certified
copy of the minutes of each Board of Directors meeting within thirty (30) days
following the date of such meeting held during the term of this Master Lease.

14.2  Financial Statements. As soon as practicable at the end of each month (and
in any event within thirty (30) days), Lessee will provide to Lessor the same
information which Lessee provides to its Board of Directors, but which will
include not less than a monthly income statement, balance sheet and statement of
cash flows prepared in accordance with generally accepted accounting principles,
consistently applied (the "Financial Statements"). As soon as practicable at the
end of each fiscal year, Lessee will provide to Lessor audited Financial
Statements setting forth in comparative form the corresponding figures for the
fiscal year (and in any event within ninety (90) days), and accompanied by an
audit report and opinion of the independent certified public accountants
selected by Lessee. Lessee will promptly furnish to Lessor any additional
information (including, but not limited to, tax returns, income statements,
balance sheets and names of principal creditors) as Lessor reasonably believes
necessary to evaluate Lessee's continuing ability to meet financial obligations.
After the effective date of the initial registration statement covering a public
offering of Lessee's securities, the term "Financial Statements" will be deemed
to refer to only those statements required by the Securities and Exchange
Commission.

14.3  Obligation to Lease Additional Equipment. Upon notice to Lessee, Lessor
will not be obligated to lease any Equipment which would have a Commencement
Date after said notice if: (i) Lessee is in default under this Master Lease or
any Schedule; (ii) Lessee is in default under any loan agreement, the result of
which would allow the lender or any secured party to demand immediate payment of
any material indebtedness; (iii) there is a material adverse change in Lessee's
credit standing; or (iv) Lessor determines (in reasonable good faith) that
Lessee will be unable to perform its obligations under this Master Lease or any
Schedule.

14.4  Merger and Sale Provisions. Lessee will notify Lessor of any proposed
Merger at least sixty (60) days prior to the closing date. Lessor may, in its
discretion, either (i) consent to the assignment of the Master Lease and all
relevant Schedules to the successor entity, or (ii) terminate the Master Lease
and all relevant Schedules. If Lessor elects to consent to the assignment,
Lessee and its successor will sign the assignment documentation provided by
Lessor. If Lessor elects to terminate the Master Lease and all relevant
Schedules, then Lessee will pay Lessor all amounts then due and owing and a
termination fee equal to the present value (discounted at 6%) of the remaining
Rent for the balance of the Initial Term(s) of all Schedules, and will return
the Equipment in accordance with Section 9. Lessor hereby consents to any Merger
in which the acquiring entity has a Moody's Bond Rating of BA3 or better or a
commercially acceptable equivalent measure of creditworthiness as reasonably
determined by Lessor.

14.5  Entire Agreement. This Master Lease and associated Schedules and Summary
Equipment Schedules supersede all other oral or written agreements or
understandings between the parties concerning the Equipment including, for
example, purchase orders. ANY AMENDMENT OF THIS MASTER LEASE OR A SCHEDULE, MAY
ONLY BE ACCOMPLISHED BY A WRITING SIGNED BY THE PARTY AGAINST WHOM THE AMENDMENT
IS SOUGHT TO BE ENFORCED.

14.6  No Waiver. No action taken by Lessor or Lessee will be deemed to
constitute a waiver of compliance with any representation, warranty or covenant
contained in this Master Lease or a Schedule. The waiver by Lessor or Lessee of
a breach of any provision of this Master Lease or a Schedule will not operate or
be construed as a waiver of any subsequent breach.

14.7  Binding Nature. Each Schedule is binding upon, and inures to the benefit
of Lessor and its assigns. LESSEE MAY NOT ASSIGN ITS RIGHTS OR OBLIGATIONS.

14.8  Survival of Obligations. All agreements, obligations including, but not
limited to those arising under Section 6.2, representations and warranties
contained in this Master Lease, any Schedule. Summary Equipment Schedule or in
any document delivered in connection with those agreements are for the benefit
of Lessor and any Assignee or Secured Party and survive the execution, delivery,
expiration or termination of this Master Lease.

14.9  Notices. Any notice, request or other communication to either party by the
other will be given in writing and deemed received upon the earlier of (1)
actual receipt or (3) three days after mailing if mailed postage prepaid by
regular or airmail to Lessor (to the attention of "the Comdisco Venture Group")
or Lessee, at the address set out in the Schedule, (3) one day after it is sent
by courier or (4) on the same day as sent via facsimile transmission, provided
that the original is sent by personal delivery or mail by the sending party.

14.10 Applicable Law. THIS MASTER LEASE HAS BEEN, AND EACH SCHEDULE WILL HAVE
BEEN MADE, EXECUTED AND DELIVERED IN THE STATE OF ILLINOIS AND WILL BE GOVERNED
AND CONSTRUED FOR ALL PURPOSES IN ACCORDANCE WITH THE LAWS OF THE STATE OF
ILLINOIS WITHOUT GIVING EFFECT TO CONFLICT OF LAW PROVISIONS. NO RIGHTS OR
REMEDIES REFERRED TO IN ARTICLE 2A OF THE UNIFORM COMMERCIAL CODE WILL BE
CONFERRED ON LESSEE UNLESS EXPRESSLY GRANTED IN THIS MASTER LEASE OR A SCHEDULE.

14.11 Severability. If any one or more of the provisions of this Master Lease or
any Schedule is for any reason held invalid, illegal or unenforceable, the
remaining provisions of this Master Lease and any such Schedule will be
unimpaired, and the invalid, illegal or unenforceable provision replaced by a
mutually acceptable valid, legal and enforceable provision that is closest to
the original intention of the parties.

14.12 Counterparts. This Master Lease and any Schedule may be executed in any
number of counterparts, each of which will be deemed an original, but all such
counterparts together constitute one and the same instrument. If Lessor grants a
security interest in all or any part of a Schedule, the Equipment or sums
payable thereunder, only that counterpart Schedule marked "Secured Party's
Original" can transfer Lessor's rights and all other counterparts will be marked
"Duplicate."

14.13 Licensed Products. Lessee will obtain no title to Licensed Products which
will at all times remain the property of the owner of the Licensed Products. A
license from the owner may be required and it is Lessee's responsibility to
obtain any required license before the use of the Licensed Products. Lessee
agrees to treat the Licensed Products as confidential information of the owner,
to observe all copyright restrictions, and not to reproduce or sell the Licensed
Products.

14.14 Secretary's Certificate. Lessee will, upon execution of this Master Lease,
provide Lessor with a secretary's certificate of incumbency and authority. Upon
the execution of each Schedule with a purchase price in excess of $1,000,000,
Lessee will provide Lessor with an opinion from Lessee's counsel in a form
acceptable to Lessor regarding the representations and warranties in Section 8.

14.15 Electronic Communications. Each of the parties may communicate with the
other by electronic means under mutually agreeable terms.

14.16 Landlord/Mortgagee Waiver. Lessee agrees to provide Lessor with a
Landlord/Mortgagee Waiver with respect to the Equipment. Such waiver shall be in
a form satisfactory to Lessor.

14.17 Equipment Procurement Charges/Progress Payments. Lessee hereby agrees that
Lessor shall not, by virtue of its entering into this Master Lease, be required
to remit any payments to any manufacturer or other third party until Lessee
accepts the Equipment subject to this Master Lease.

14.18 Definitions.

Advance - means the amount due to Lessor by Lessee upon Lessee's execution of
--------
each Schedule.

Assignee - means an entity to whom Lessor has sold or assigned its rights as
---------
owner and Lessor of Equipment.

Casualty Loss - means the irreparable loss or destruction of Equipment.
-------------

Casualty Value - means the greater of the aggregate Rent remaining to be paid
---------------
for the balance of the lease term or the Fair Market Value of the Equipment
immediately prior to the Casualty Loss. However, if a Casualty Value Table is
attached to the relevant Schedule its terms will control.

Commencement Date - is defined in each Schedule.
------------------

Default Costs - means reasonable attorney's fees and remarketing costs resulting
-------------
from a Lessee default or Lessor's enforcement of its remedies.

Delivery Date - means date of delivery of Inventory Equipment to Lessee's
--------------
address.

Equipment - means the property described on a Summary Equipment Schedule and any
----------
replacement for that property required or permitted by this Master Lease or a
Schedule.

Event of Default - means the events described in Subsection 13.1.
-----------------
<PAGE>

Fair Market Value - means the aggregate amount which would be obtainable in an
------------------
arm's-length transaction between an informed and willing buyer/user and an
informed and willing seller under no compulsion to sell.

Initial Term - means the period of time beginning on the first day of the first
------------
full Rent Interval following the Commencement Date for all items of Equipment
and continuing for the number of Rent Intervals indicated on a Schedule.

Interim Rent - means the pro-rata portion of Rent due for the period from the
------------
Commencement Date through but not including the first day of the first full Rent
Interval included in the Initial Term.

Late Charge - means the lesser of five percent (5%) of the payment due or the
-----------
maximum amount permitted by the law of the state where the Equipment is located.

Licensed Products - means any software or other licensed products attached to
-----------------
the Equipment.

Like Equipment - means replacement Equipment which is lien free and of the same
--------------
model, type, configuration and manufacture as Equipment.

Merger - means any consolidation or merger of the Lessee with or into any other
-------
corporation or entity, any sale or conveyance of all or substantially all of the
assets or stock of the Lessee by or to any other person or entity in which
Lessee is not the surviving entity.

Notice Period - means not less than ninety (90) days nor more than twelve (12)
--------------
months prior to the expiration of the lease term.

Owner - means the owner of Equipment.
------

Rent - means the rent Lessee will pay for each item of Equipment expressed in a
-----
Summary Equipment Schedule either as a specific amount or an amount equal to the
amount which Lessor pays for an item of Equipment multiplied by a lease rate
factor plus all other amounts due to Lessor under this Master Lease or a
Schedule.

Rent Interval - means a full calendar month or quarter as indicated on a
--------------
Schedule.

Schedule - means either an Equipment Schedule or a Licensed Products Schedule
---------
which incorporates all of the terms and conditions of this Master Lease.

Secured Party - means an entity to whom Lessor has granted a security interest
--------------
for the purpose of securing a loan.

Summary Equipment Schedule - means a certificate provided by Lessor summarizing
---------------------------
all of the Equipment for which Lessor has received Lessee approved vendor
invoices, purchase documents and/or evidence of delivery during a calendar
quarter which will incorporate all of the terms and conditions of the related
Schedule and this Master Lease and will constitute a separate lease for the
equipment leased thereunder.

IN WITNESS WHEREOF, the parties hereto have executed this Master Lease on or as
of the day and year first above written.

CHORUM TECHNOLOGIES, INC.                       COMDISCO, INC.,
as Lesee                                        as Lessor

By:    /s/ Scott Grout                          By:   /s/ James C. Labe
   -----------------------------                   ---------------------------

Title:   President and CEO                      Title:   President
       -------------------------                      -----------------------
<PAGE>

                                ADDENDUM TO THE
             MASTER LEASE AGREEMENT DATED AS OF SEPTEMBER 22, 1998
                  BETWEEN CHORUM TECHNOLOGIES, INC., AS LESSEE
                         AND COMDISCO, INC., AS LESSOR

The undersigned hereby agree that the terms and conditions of the above
referenced Master Lease Agreement are hereby modified and amended as follows:

1)   Section 3. "Rent and Payment."
                 -----------------

     Insert the following at the end of the second sentence after the word
     "amount",

     "provided, however, that so long as payment is made within five (5) days
     after the date such payment is due, no late charge will be assessed for up
     to two (2) late payments under a particular Summary Equipment Schedule."

     Delete the second sentence and the last 3 sentences of this section.

2)   Section 4.2 "Warranty and Disclaimer of Warranties."
                  --------------------------------------

     In line 2, delete "Lessee is not in default" and replace with "No Event of
     Default exists".

3)   Section 5.2 "Relocation or Sublease."
                  ------------------------

     Second paragraph, first sentence, lines 1 and 2, delete the words "and the
     Secured Party".

4)   Section 5.3 "Assignment by Lessor."
                 -----------------------

     Paragraph (a), second sentence, lines 3 and 4, delete "Lessee is not in
     default and the Secured Party continues to receive all Rent payable under
     the Schedule" and insert "no Event of Default has occurred and is
     continuing".

5)   Section 6.2 "Taxes and Fees."
                  ----------------

     First sentence, lines 5 and 6, delete "only Federal, state, local and
     franchise taxes on the capital or the net income of Lessor" and insert the
     following:

     "Excluded Taxes. Excluded Taxes means (a) taxes based upon, measured by or
     with respect to the net or gross income, items of tax preference or minimum
     tax or excess profits, receipts, capital, franchise, net worth or
     similarly-based taxes, (b) taxes on items of tax preference or any minimum
     tax or alternative minimum tax, (c) taxes imposed with respect to any
     period after either (i) Lessee's payment of the Casualty Value hereunder,
     provided, however such amounts shall be limited to taxes for those items
     for which a Casualty Value was
<PAGE>

     paid and, or (ii) the expiration or earlier termination of the Initial Term
     or the extended term, as applicable, and either (A) the return of the
     Equipment pursuant to the Lease or (B) the transfer of Lessor's interest in
     the Equipment pursuant to any purchase or termination option, (d) taxes
     resulting from the misconduct, negligence or breach by Lessor, (e) taxes
     which become payable by reason of any transfer by Lessor of its interest in
     the Equipment or the Summary Equipment Schedule, other than in connection
     with its exercise of any remedies hereunder, (f) taxes subject to any other
     indemnification hereunder, (g) taxes imposed on a successor, assignor, or
     other transferee of Lessor to the extent that such taxes would not have
     been imposed on the original Lessor or exceed the amount of taxes that
     would have been imposed and would have been indemnifiable pursuant to this
     indemnity had there not been a succession, assignment or other transfer by
     such original Lessor, (h) taxes imposed by any jurisdiction that would not
     have been imposed on Lessor but for its activities or status in such
     jurisdiction unrelated to the transactions contemplated hereby and (i) any
     taxes included in the purchase price of the Equipment leased hereunder."

6)   Section 7.1 "Care. Use and Maintenance."
                  --------------------------

     Second sentence, line 4, after the words "and will provide Lessor" insert
     "upon request".

     Delete the last two sentences of this section.

7)   Section 8. "Representations and Warranties."
                 -------------------------------

     In paragraph (b), line 7, after "which is bound" insert ", which default
     could have a material effect on Lessee".

     In paragraph (d), line 1, after "Equipment" insert "(excluding any software
     and/or tenant improvements financed hereunder)".

     In paragraph (e), line 3, after "in the Financial Statements" insert "most
     recently delivered hereunder".

     Paragraph (f), at the end thereof insert "such that such infringement could
     have a material adverse effect on the Lessee's business operations.".

     Paragraph (g), at the end thereof insert "except where failure of such
     contract, agreement or instrument to be in full force and effect will not
     have a material adverse effect on the Lessee's business operations."
<PAGE>
8)   Section 9. "Delivery and Return."
                 --------------------

     Insert the following between the second and third sentences, insert:
     "Lessee may remove any alteration or attachment to the Equipment not
     specifically required to be delivered to Lessor hereunder or which is not
     permanently attached to the Equipment."

     Fourth sentence, line 2, after the words "operation in place" insert
     "during normal business hours and so long as it does not unreasonably
     interfere with Lessee's operations".

9)   Section 10. "Labeling."
                  ---------

     In line 1, after "Lessee will" insert "use best efforts".

10)  Section 11. "Indemnity."
                  ----------

     Second sentence, line 3, after the words "negligent acts" insert "or
     willful misconduct".

     At the end of this section insert the following:

     "Lessor shall not enter into any settlement or other compromise with
     respect to any claim covered by the indemnity set forth in this section
     without Lessee's prior written consent, which shall not be unreasonably
     withheld, conditioned or delayed, and if a claim is settled or compromised
     without such consent, Lessee shall not be obligated to provide
     indemnification under this section. If Lessor or any other indemnified
     party obtains recovery of any of the amounts that Lessee has paid to them
     pursuant to the indemnity set forth in this section, then Lessor or such
     other indemnified party, as applicable, shall promptly pay to Lessee the
     amount of such recovery.".

11)  Section 13.1 "Default."
                   --------

     In paragraph (b), line 4, delete "ten (10) business" and replace with
     "thirty (30)".

12)  Section 13.2. "Remedies."
                    ---------

     In paragraph (d), line 5, after "negligence" insert "or willful
     misconduct."

     To the end of this section add: "Any such successive or cumulative exercise
     is not intended to provide Lessor with a greater return than it would have
     received had Lessee fully performed under the terms of the applicable
     Summary Equipment Schedule."

<PAGE>
13)  Section 14.1 "Board Attendance."
                   -----------------

     Delete this section in its entirety.

14)  Section 14.2 "Financial Statements."
                   ---------------------

     First sentence, lines 2 and 3, delete "the same information which Lessee
     provides to its Board of Directors, but which will include not less than"
     and on line 4, delete "statement of cash flows".

     Second sentence, line 3, after "comparative form" insert "(if applicable")
     and replace "ninety (90)" with "one hundred twenty (120)".

     In the last sentence, delete the term "Financial Statements will be deemed
     to refer to only those statements required by the Securities and Exchange
     Commission" and replace with "This section shall be of no further force or
     effect."

15)  Section 14.3., "Obligation to Lease Additional Equipment"
                     ----------------------------------------

     In line 3, after "or any Schedule" insert "and such default has not been
     cured or waived". In line 4, after "under any loan agreement" insert "so
     long as such default exists,".

15)  Section 14.4 "Merger and Sale Provisions."
                   ---------------------------

     First sentence, lines 1 and 2, delete "at least sixty (60) days prior to
     the closing date" and insert "no later than the date notice thereof is
     provided to Lessee's shareholders".

     At the end of this section add, "Lessor's consent hereunder will not be
     unreasonably delayed or conditioned."

16)  Section 14.14 "Secretary's Certificate."
                    ------------------------

     Delete the last sentence of this section.

              [Remainder of this page intentionally left blank]
<PAGE>

17)  Section 14.18 "Definitions."
                    -------------

     Definition of "Casualty Value", is revised in its entirety to read: "means
                    --------------
     the value specified in the Casualty Value table attached hereto and made a
     part hereof."

Except as amended hereby, all other terms and conditions of the Master Lease
Agreement remain in full force and effect.

CHORUM TECHNOLOGIES, INC.                         COMDISCO, INC. as LESSOR
as LESSEE                                         as LESSOR

By:     /s/ Scott Grout                           By:    /s/ James P. Labe
   ---------------------------                        -------------------------

Title:  President and CEO                         Title: President
      ------------------------                          -----------------------

Date:   9/23/98                                    Date: 9/28/98
      ------------------------                          -----------------------
<PAGE>

                          LOAN AND SECURITY AGREEMENT

THIS AGREEMENT (the "Agreement"), dated as of September 22, 1998 is entered into
by and between Chorum Technologies, Inc., a Delaware corporation having a
principal place of business at 1155 East Collins Blvd., Suite 200, Richardson,
TX 75081 (the "Borrower") and Comdisco, Inc., a Delaware corporation having a
principal place of business at 6111 North River Road, Rosemont, Illinois 60018
(the "Lender" ). In consideration of the mutual agreements contained herein, the
parties hereto agree as follows:

     WHEREAS, Borrower desires to borrow from the Lender hereunder the amount of
EIGHT HUNDRED SEVENTY THOUSAND SIX HUNDRED EIGHT-THREE AND 37/00 DOLLARS
($870,683.37) and Lender is willing to lend said amount to Borrower on September
30, 1998 (the "Funding Date");

           NOW, THEREFORE, it is agreed:

SECTION 1. THE LOAN

     1.1  Subject to the terms and conditions set forth herein, Lender shall
lend to Borrower the aggregate original principal of EIGHT HUNDRED SEVENTY
THOUSAND SIX HUNDRED EIGHT-THREE AND 37/00 DOLLARS ($870,683.37) (the "Loan")
with interest at the rate of seven and one quarter percent (7.25%) per annum
payable in monthly installments as set forth in the promissory note (the
"Note") in the form attached hereto and made a part hereof as Exhibit A, dated
September 30, 1998.

     1.2  Upon the occurrence of and during an Event of Default (as defined
herein), interest shall thereafter be calculated at a rate of five percent (5%)
in excess of the rate that would otherwise be applicable ("Default Rate"). All
such interest shall be due and payable in arrears, on the first day of the
following month.

     1.3  Notwithstanding any provision in this Agreement, the Note, or any
other "Loan Document" (as defined herein), it is not the parties' intent to
contract for, charge or receive interest at a rate that is greater than the
maximum rate permissible by law which a court of competent jurisdiction shall
deem applicable hereto (which under the laws of the State of Illinois shall be
deemed to be the laws relating to permissible rates of interest on commercial
loans) (the "Maximum Rate"). If the Borrower actually pays Lender an amount of
interest, chargeable on the total aggregate principal Obligations of Borrower
under this Agreement and the Note (as said rate is calculated over a period of
time that is the longer of (i) the time from the date of this Agreement through
the maturity time as set forth on the Note, or (ii) the entire period of time
that any principal is outstanding on the Note), which amount of interest exceeds
interest calculated at the Maximum Rate on said principal chargeable over said
period of time, then such excess interest actually paid by Borrower shall be
applied first, to the payment of principal outstanding on the Note; second,
after all principal is repaid, to the payment of Lender's out of pocket costs,
expenses, and professional fees which are owed by Borrower to Lender under the
Agreement or the Loan Documents; and third, after all principal, costs,
expenses, and professional fees owed by Borrower to Lender are repaid, the
excess (if any) shall be refunded to Borrower.
<PAGE>

     1.4  In the event any interest is not paid when due hereunder, delinquent
interest shall be added to principal and shall bear interest on interest,
compounded at the rate set forth in section 1.1.

     1.5  Upon and during the continuation of an Event of Default hereunder (as
defined herein), all Obligations, including principal, interest, compounded
interest, and reasonable professional fees, shall bear interest at a rate per
annum equal to the Default Rate.

     1.6  Borrower shall have the option to prepay the Note, in whole or in
part, at any time after the date hereof by paying the principal amount together
with all accrued and unpaid interest with respect to such principal amount, as
of the date of such prepayment and the present value of the Balloon Payment as
described in the Note together with a prepayment premium equal to the
difference, if any, between (x) the amount being prepaid and (y) the present
value, discounted at the Treasury Rate, of each installment of principal and
interest being prepaid discounted to the date of prepayment. If the amount in
(x) is greater than the amount in (y), no prepayment premium shall be due. The
"Treasury Rate" shall mean the then prevailing yield on US Treasury Constant
Maturities for the most recent business day, as quoted in the Federal Reserve
Statistical Release H15, as of the date of prepayment for an obligation of
comparable maturity to the maturity date of the Note.

SECTION 2. SECURITY INTEREST

     As security for the payment of all indebtedness ("Indebtedness") of the
Borrower to the Lender hereunder and under the Note, as the same may be renewed,
extended for any period or rearranged, and the performance by the Borrower of
its other obligations hereunder (the Indebtedness and such other obligations
being hereinafter sometimes collectively referred to as the "Obligations"), the
Borrower hereby assigns to the Lender, and grants to the Lender a first priority
security interest in, all the Borrower's right, title, and interest in and to
the following property ("Collateral"): (i) the equipment and other property (the
"Equipment") described in Exhibit B attached hereto; and (ii) all proceeds,
products, replacements, additions to, substitutions for and accessions to any
and all Equipment including, without limitation, the proceeds applicable to the
insurance referred to in Section 4 hereof.

SECTION 3. REPRESENTATIONS AND WARRANTIES OF BORROWER

The Borrower represents, warrants and agrees that:

     3.1  it has good title in and to the Equipment, free of all liens, security
interests, encumbrances and claims whatsoever, except for the interest of the
Lender therein and Permitted Liens;

     3.2  it has the full power and authority to, and does hereby grant and
convey to the Lender, a valid first priority (and when the requisite financing
statements are properly filed) perfected security interest in the Equipment as
security for the Obligations, free of all liens, security interests,
encumbrances and claims other than Permitted Liens, and shall execute such
Uniform Commercial Code ("UCC") financing statements in connection herewith as
the Lender may reasonably request. No other lien, security interest, adverse
claim or encumbrance has been created by Borrower or is known by Borrower to
exist with respect to any Collateral other than Permitted Liens. Permitted Liens
means the following;
<PAGE>

     (a)   liens for taxes, fees, assessments or other governmental charges or
levies, either not delinquent or being contested in good faith by appropriate
proceedings, provided the same have no priority over any of Lender's security
interests:

     (b)   liens securing claims or demands or materialmen, mechanics, carriers,
warehousemen, landlords and other like persons or entities imposed without
action of such parties, provided that the payment thereof is not yet required;
and

     (c)   liens arising from judgements, decrees or attachments in
circumstances not constituting an Event of Default hereunder.

     3.3   it is a corporation duly organized, legally existing and in good
standing under the laws of the State of Delaware, and is duly qualified as a
foreign corporation in all jurisdictions where the failure to so qualify would
have a material adverse effect on the Collateral or the business of the Borrower
taken as a whole;

     3.4   the execution, delivery and performance of the Note, this Agreement,
the Warrant Agreement dated September __, 1998 pursuant to which Borrower
granted to Lender the right to purchase the number of shares of preferred stock
as set forth therein ("Warrant Agreement"), and all financing statements,
certificates and other documents required to be delivered or executed in
connection herewith (collectively, the "Loan Documents") have been duly
authorized by all necessary corporate action of Borrower, the individual or
individuals executing the Documents were duly authorized to do so, the Equipment
is personal property and as used by the Borrower will not be or become fixtures
under applicable law, with the exception of the fixtures listed on Exhibit B,
and the Loan Documents constitute legal, valid and binding obligations of the
Borrower, enforceable in accordance with their respective terms, subject to
applicable bankruptcy, insolvency, reorganization or other similar laws
generally affecting the enforcement of the rights of creditors;

     3.5   the Loan Documents do not and will not violate any provisions of its
articles or certificate of incorporation, bylaws or any contract, agreement,
law, regulation, order, injunction, judgment, decree or writ to which the
Borrower is subject, or result in the creation or imposition of any lien,
security interest or other encumbrance upon the Collateral, other than those
created by this Agreement;

     3.7   the execution, delivery and performance of the Loan Documents do not
require the consent or approval of any other person or entity including, without
limitation, any regulatory authority or governmental body of the United States
or any state thereof or any political subdivision of the United States or any
state thereof.

SECTION 4. INSURANCE AND RISK OF LOSS

     4.1   Risk of loss of, damage to or destruction of the Equipment shall be
borne by the Borrower and effective upon the Funding Date under the Note and
until the payment and performance in full of all Obligations, Borrower shall at
its own expense cause to be carried and maintained all risk casualty insurance
(covering risk of fire, theft and other such risks as similarly situated
companies insure against) with respect to each item of Equipment in an amount no
less than the replacement costs applicable to such item of Equipment during the
term of this
<PAGE>

Agreement. All policies evidencing such casualty insurance shall contain
a standard mortgagee's endorsement and shall provide for at least thirty days
prior written notice by the underwriter or insurance company to the Lender in
the event of cancellation or expiration. Borrower shall provide Lender with
insurance certificates evidencing the foregoing at time of closing.

     4.2   If any item of Equipment is lost or rendered unusable as a result of
any physical damage to or destruction of such item of Equipment during the
period from the Funding Date to the date all Obligations hereunder have been
fully satisfied, Borrower shall give to Lender prompt notice thereof. Borrower
shall determine, within fifteen (15) days after the date of occurrence of such
loss, damage or destruction, whether such item of Equipment can be repaired and
restored to the condition in which such item of Equipment was required to be
maintained as of the date immediately preceding such damage. If Borrower
determines that such item of Equipment can be repaired and Borrower elects to
make such repairs, Borrower, at its expense, shall cause such item of Equipment
to be promptly repaired If Borrower determines that such item of Collateral is
lost, cannot be repaired or Borrower elects not to make repairs, Borrower shall
promptly notify the Lender and such item of Equipment shall be deemed to have
suffered a "Casualty Loss" for purposes of this Section as of the date of the
occurrence of such loss. Within fifteen (15) days following the occurrence of
any such loss, damage or destruction, Borrower shall notify the Lender of the
item(s) of Equipment which has suffered such Casualty Loss ("Loss Item"), and
within thirty (30) days thereafter (the "Settlement Date"), Borrower shall
either (a) replace such item(s) of Equipment with equipment of the same model,
type and feature configuration, in an operating condition and repair no less
than that required hereunder of the damaged or lost equipment immediately prior
to the date of such damage or loss, in which case such replacement equipment
shall for all purposes hereunder become part of the Collateral and (without
limiting the preceding provisions) Borrower shall grant to Lender a first lien
and security interest in respect of such replacement equipment pursuant to the
terms of this Agreement, and Borrower shall provide the Lender evidence
satisfactory to the Lender of Borrower's good and marketable title to such
replacement equipment (free of any liens, security interests or encumbrances
other than those created by this Agreement and Permitted Liens and Borrower
shall be entitled to receive the amount of any insurance or other recovery
received by Lender up to cost of obtaining the replacement equipment; or (b) so
long as no Event of Default or event which with the giving of notice or passage
of time, or both, would constitute an Event of Default, has occurred and is
continuing, Borrower may provide substitute equipment satisfactory to Lender to
become part of the Collateral and Borrower shall grant to Lender a first lien
and security interest in respect of such substitute equipment pursuant to the
terms of this Agreement, and Borrower shall provide the Lender evidence
satisfactory to Lender of Borrower's good and marketable title to such
substitute equipment (free of any liens, security interests or encumbrances
other than created by this Agreement and Permitted Liens and Lender shall
provide any required endorsements in connection with any insurance proceeds
received by Borrower pursuant to such insurance policies; or (c) Borrower shall
pay Lender the insurance proceeds payable pursuant to such insurance policies
("Insurance Proceeds")with respect to such Loss Item(s) and the principal amount
of the Note (and interest accrued on the principal amount so prepayable) shall
become due and payable on the Settlement Date to the extent of the replacement
cost for all such Loss Item(s). Moneys so received shall be applied, on the date
of such receipt, as follows: first, to pay any accrued interest on the
outstanding principal amount of the Note on such date; second, to prepay, the
outstanding principal amount of the Note (to the extent of the Casualty Value
(See Exhibit 1 ) of such Loss Item(s)); third, to pay any other Indebtedness of
amounts then due and owing to the Lender hereunder; and fourth, so long as there
has occurred no Event of
<PAGE>

Default under Section 8 hereof and no event which with the giving of notice or
passage of time or both would constitute an Event of Default, has occurred and
is continuing, Borrower and Lender hereby agree that the balance of any such
Insurance Proceeds shall be paid promptly to the Borrower.

     4.3  Effective upon the Funding Date under the Note and while there are
any Obligations outstanding, Borrower shall cause to be carried and maintained
comprehensive general liability insurance with regard to the Collateral against
risks customarily insured against in the Borrower's business. Such risks shall
include, without limitation, the risks of death, bodily injury and property
damage associated with the Collateral. All policies evidencing such insurance
shall provide for at least thirty (30) days prior written notice by the
underwriter or insurance company to the Lender in the event of cancellation or
expiration.

     4.4  Borrower shall and does hereby indemnify and hold Lender, its agents
and shareholders harmless from and against any and all claims, costs, expenses,
damages and liabilities (including without limitation such claims, costs,
expenses, damages and liabilities based on liability in tort including without
limitation strict liability in tort) including reasonable attorneys' fees,
arising out of Borrower's ownership, possession, operation, control, use,
maintenance, delivery, or other disposition of the Collateral. Notwithstanding
the foregoing, Borrower shall not be responsible under the terms of this Section
4.4 to a party indemnified hereunder for any claims, costs, expenses, damages
and liabilities occasioned by the negligence or willful misconduct of such
indemnified party.

     Lender may not enter into any settlement or other compromise with respect
to any claim covered by the indemnity set forth in this section without
Borrower's prior written consent, which shall not be unreasonably withheld,
conditioned or delayed, and if a claim is settled or compromised without such
consent, Borrower shall not be obligated to provide indemnification under this
section. If Lender or any other indemnified party obtains recovery of any of the
amounts that Borrower has paid to them pursuant to the indemnity set forth in
this section, then Lender or such other indemnified party, as applicable, shall
promptly pay to Borrower the amount of such recovery.

SECTION 5. COVENANTS OF BORROWER

     Borrower covenants and agrees as follows at all times while any of the
Obligations remain outstanding:

     5.1  Borrower shall maintain the Equipment in good operating order, repair,
condition and appearance and protect the Equipment from deterioration, other
than normal wear and tear. Borrower shall not use any of the Equipment or permit
its use for any purpose other than for which it was designed. Borrower's
obligation regarding the maintenance of the Equipment shall include, without
limitation, all maintenance, repair, refurbishment and replacement recommended
or advised either by the manufacturer, or that commonly performed by prudent
business and/or professional practice. Any exceptions or qualifications
expressed in this Agreement relating to normal or ordinary wear and tear shall
not be deemed to limit Borrower's obligations pursuant to the preceding
sentence.
<PAGE>

     5.2   Borrower shall only relocate any item of the Equipment provided
that: (a) it shall have caused to be filed and/or delivered to the Lender all
UCC financing statements, certificates or other documents or instruments
necessary to continue in effect the first prior perfected security interest of
the Lender in the Collateral, and (b) it shall have given the Lender no less
than fifteen (15) days prior written notice of such relocation;

     5.3   In the event Borrower adds or installs any Upgrade (as hereinafter
defined) on the Equipment, at the request of Lender, Borrower shall, upon
Lender's demand made in conjunction with a sale or other disposition of the
Equipment during the occurrence of an Event of Default, remove any such Upgrade
and restore the Equipment to the condition in which such Equipment is required
to be maintained hereunder as if such Upgrade had never been attached thereto.
Borrower will not, without the prior written consent of Lender (which shall not
unreasonably withheld, delayed or conditioned in the case of tenant
improvements) and subject to such conditions as Lender may impose for its
protection, affix the Equipment to any real property if, as a result thereof,
the Equipment could become a fixture under applicable law.

     For purposes hereof and all Loan Documents relating hereto, the term
"Upgrade" shall mean: (i) any accessory, equipment or device manufactured or
sold by the manufacturer of the Equipment for installation on the Equipment and
installed in compliance with said manufacturer's installation procedures (other
than those added by the manufacturer in order to maintain the Equipment at
current engineering levels), or (ii) any other accessory, equipment or device
installed on the Equipment so long as such item does not impair the original
function or use of the Equipment, capable of being removed without causing
material damage to the Equipment and does not decrease the fair market value of
the Equipment. An Upgrade shall not become an accession to the Equipment. For
purposes hereof and of all Loan Documents relating hereto, the term "Equipment"
shall not be deemed to include any such Upgrade.

     5.4   Upon the request of Lender, Borrower shall, during business hours,
make the Equipment available to Lender for inspection at the place where it is
normally located and shall make Borrower's log and maintenance records
pertaining to the Equipment available to the Equipment available to Lender for
inspection. Borrower shall take all action necessary to maintain such logs and
maintenance records in a correct and complete fashion.

     5.5   Upon the request of Lender, Borrower shall cause the Equipment to be
plainly, permanently and conspicuously marked, by stenciling or by metal tag or
plate affixed thereto, indicating Lender's security interest in the Equipment.
Borrower shall replace any such stenciling, tag or plate which may be removed or
destroyed or become illegible. Borrower shall keep all Equipment free from any
marking or labeling which might be interpreted as a claim of ownership adverse
to Borrower's.

     5.6   Borrower covenants and agrees to pay when due, all taxes, fees or
other charges of any nature whatsoever (together with any related interest or
penalties) now or hereafter imposed or assessed against Borrower, Lender or the
Equipment or upon Borrower's ownership, possession, use, operation or
disposition thereof or upon Borrower's rents, receipts or earnings arising
therefrom. Borrower shall file on or before the due date therefor all personal
property tax returns in respect of the Equipment. The foregoing not
withstanding, Borrower need not make any payment described in this Section 5.6
if the amount or the validity thereof of such payment is being contested in good
faith by appropriate proceedings and is reserved against to the extent required
by GAAP.
<PAGE>

     5.7   Borrower shall furnish to Lender the financial statements listed
hereinafter, prepared in accordance with generally accepted accounting
principles consistently applied (the "Financial Statements"):

          (a) as soon as practicable (and in any event within thirty (30) days)
     after the end of each month: an intemally prepared income statement and
     balance sheet, each prepared in accordance with generally accepted
     accounting principles, consistently applied , (including a report as to the
     commencement of any material litigation by or against Borrower;

          (b) as soon as practicable (and in any event within one hundred twenty
     (120) days) after the end of each fiscal year, audited Financial
     Statements, setting forth in comparative form the corresponding figures for
     the preceding fiscal year (if available), and accompanied by any audit
     report and opinion of the independent certified public accountants selected
     by Borrower; and

          (c) promptly any additional information (including but not limited to
     tax returns, income statements, balance sheets, and names of principal
     creditors) as Lender reasonably believes necessary to evaluate Borrower's
     continuing ability to meet financial obligations.

     5.8  Notwithstanding the foregoing, after the effective date of the
initial registration statement covering a public offering of Borrower's
securities, the term "Financial Statements" shall be deemed to refer to only
those statements required by the Securities and Exchange Commission, to be
provided no less frequently than quarterly. Borrower will from time to time
execute, deliver and file, alone or with Lender, any financing statements,
security agreements or other documents; and take all further action that may be
necessary, or that Lender may reasonably request, to confirm, perfect, preserve
and protect the security interests intended to be granted hereby, and in
addition, and for such purposes only, Borrower hereby authorizes Lender to
execute and deliver on behalf of Borrower and to file such financing statements,
security agreement and other documents without the signature of Borrower either
in Lender's name or in the name of Borrower as agent and attorney-in-fact for
Borrower.

     5.9  Borrower shall protect and defend Borrower's title as well as the
interest of the Lender against all persons claiming any interest adverse to
Borrower or Lender and shall at all times keep the Collateral free and clear
from any attachment or levy, liens or encumbrances whatsoever (except any placed
thereon by Lender, or any Permitted Liens) and shall give Lender immediate
written notice thereof.

     5.10 Upon the occurrence of an Event of Default, if Lender seeks to
foreclose on the Equipment, Borrower shall be liable for the full expense of
transportation and in-transit insurance to Lender's, Borrower's liability for
expense of transportation of the Equipment shall be limited to the costs of
transportation to such warehouse space, Borrower will arrange for the
deinstallation and audit of the Equipment, and will pack; ship and send the
Equipment to Lender in good operating order, repair, condition and appearance,
and in a condition required pursuant to Section 5.1 hereof.
<PAGE>

     SECTION 6. CONDITIONS PRECEDENT TO LOAN

     On or prior to the Funding Date, Borrower will provide to Lender the
following, in form and substance satisfactory to Lender:

     6.1  Such documentation, including, without limitation, a Bill of Sale,
and other documents as shall reasonably evidence Borrower's right, title and
interest in and to the Equipment;

     6.2  A certified resolution or other certificate of corporate authority for
the execution and the delivery of, and the performance of all Obligations under
the Loan Documents and all related documentation;

     6.3  Incumbency certificate evidencing the authority and facsimile
signatures of the individuals executing the Loan Documents;

     6.4  UCC financing statements as deemed appropriate by Lender to perfect
its security interest in the Collateral;

     6.5  Certified copies of the Certificate of Incorporation of Borrower;

     6.6  Certificate of good standing for Borrower from its state of
incorporation and similar certificates from all jurisdictions in which it does
business and where the failure to be qualified would have a material adverse
effect on Borrower's business; and

     6.7  Insurance certificates as required by Section 4 hereof.

SECTION 7. ASSIGNMENT BY LENDER

     7.1  Borrower acknowledges and understands that Lender may sell and assign
all or a part of its interest hereunder and under the Note and Loan Documents to
any person or entity (an "Assignee"). After such assignment the term Lender
shall mean such Assignee, and such Assignee shall be vested with all rights,
powers and remedies of Lender hereunder with respect to the interest so
assigned; but with respect to any such interest not so transferred, the Lender
shall retain all rights, powers and remedies hereby given. No such assignment by
Lender shall relieve Borrower of any of its obligations hereunder. Borrower
shall acknowledge such assignment or assignments as shall be designated by
written notice given by Lender to Borrower. The Lender agrees that in the event
of any transfer by it of the Note, it will endorse thereon a notation as to the
portion of the principal of the Note which shall have been paid at the time of
such transfer and as to the date to which interest shall have been last paid
thereon.

SECTION 8. DEFAULT

     The occurrence of any one or more of the following events (herein called
"Events of Default") shall constitute a default hereunder and under the Note:

     8.1  The Borrower defaults in the payment of any principal or interest
payable under the Note for more than five (5) days after the receipt of notice
of such an Event of Default from Lender;
<PAGE>

     8.2   The Borrower defaults in the payment or performance of any other
covenant or obligation of the Borrower hereunder or under the Note or any other
Loan Documents for more than thirty (30) days after the Lender has given notice
of such default to the Borrower;

     8.3   Any representation or warranty made herein by the Borrower shall
prove to have been false or misleading in any material respect as of the date
made;

     8.4   The making of an assignment by Borrower for the benefit of its
creditors or the admission by Borrower in writing of its inability to pay its
debts as they become due, or the insolvency of Borrower, or the filing by
Borrower of a voluntary petition in bankruptcy, or the adjudication of Borrower
as a bankrupt, or the filing by Borrower of any petition or answer seeking for
itself any reorganization, arrangement, composition, readjustment, liquidation,
dissolution, or similar relief under any present or future statute, law or
regulation, or the filing of any answer by Borrower admitting, or the failure by
Borrower to deny, the material allegations of a petition filed against it for
any such relief, or the seeking or consenting by Borrower to, or acquiescence by
Borrower in, the appointment of any trustee, receiver or liquidator of Borrower
or of all or any substantial part of the properties of Borrower, or the
inability of Borrower to pay its debts when due, or the commission by Borrower
of any act of bankruptcy as defined in the Federal Bankruptcy Act, as amended;

     8.5  The failure by Borrower, within sixty (60) days after the
commencement of any proceeding against Borrower seeking any reorganization,
arrangement, composition, readjustment, liquidation, dissolution or similar
relief under any present or future statute, law or regulation, to obtain the
dismissal of such proceeding or, within sixty (60) days after the appointment,
without the written consent or acquiescence of Lender, of any trustee, receiver
or liquidator of Borrower or of all or any substantial part of the properties of
Borrower, to vacate such appointment; or

     8.6  The occurrence of an Event of Default by Borrower under any other
notes or other agreement for borrowed money, lease or other agreement between
Borrower and Lender. The Event of Default under this Section 8.6 caused by the
occurrence of an Event of Default under another agreement described in this
Section 8.6 shall be automatically cured for purposes of this Agreement upon the
cure or waiver of the Event of Default under the other agreement.

SECTION 9. REMEDIES

     Upon the occurrence hereof of any one or more Events of Default, Lender, at
its option, may declare the Note to be accelerated and immediately due and
payable, (provided, that upon the occurrence of an Event of Default of the type
described in Section 8.4 or Section 8.5, the Note and all other Obligations
shall automatically be accelerated and made due and payable without any further
act) whereupon the unpaid principal of and accrued interest on such Note shall
become immediately due and payable, and shall thereafter bear interest at the
Default Rate and calculated in accordance with Section 1.2. Lender may exercise
all rights and remedies with respect to the Collateral granted pursuant hereto
for such Note, or otherwise available to it under applicable law, including the
right to release, hold or otherwise dispose of all or any part of the Collateral
and the right to utilize, process and commingle the Collateral.

     Upon the happening and during the continuance of any Event of Default,
Lender may then, or at any time thereafter and from time to time, apply,
collect, sell in one or more sales,
<PAGE>

lease or otherwise dispose of, any or all of the Collateral, in its then
condition or following any commercially reasonably preparation or processing, in
such order as Lender may elect, and any such sale may be made either at public
or private sale at its place of business or elsewhere.

Borrower agrees that any such public or private sale may occur upon ten (10)
calendar day's notice to Borrower. Lender may require Borrower to assemble the
Collateral and make it available to Lender at a place designated by Lender which
is reasonably convenient to Lender and Borrower. The proceeds of any sale,
disposition or other realization upon all or any part of the collateral shall be
distributed by Lender in the following order of priorities:

     First, to Lender in an amount sufficient to pay in full Lender's reasonable
     costs and professionals' and advisors' fees and expenses;

     Second, to Lender in an amount equal to the then unpaid amount of the
     Obligations in such order and priority as Lender may choose in its sole
     discretion; and

     Finally, upon payment in full of all of the Obligations, to Borrower or its
     representatives. or as a court of competent jurisdiction may direct.

The Lender shall return to the Borrower any surplus Collateral remaining-after
payment of all Obligations.

SECTION 10. MISCELLANEOUS

     10.1 Borrower shall remain liable to Lender for any unpaid Obligations,
advances, costs, charges and expenses, together with interest thereon and shall
pay the same immediately to Lender at Lender's offices.

     10.2 The powers conferred upon Lender by this Agreement are solely to
protect its interest in the Collateral and shall not impose any duty upon Lender
to exercise any such powers.

     10.3 This is a continuing Agreement and the grant of a security interest
hereunder shall remain in full force and effect and all the rights, powers and
remedies of Lender hereunder shall continue to exist until the Obligations are
paid in full as the same become due and payable.

When Borrower has paid in full all Obligations, Lender will execute a written
termination statement, reassigning to Borrower, without recourse, the Collateral
and all rights conveyed hereby and return possession (if Lender has possession)
of the Collateral to Borrower. The rights, powers and remedies of Lender
hereunder shall be in addition to all rights, powers and remedies given by
statute or rule of law and are cumulative. The exercise of any one or more of
the rights, powers and remedies provided herein shall not be construed as a
waiver of any other rights, powers and remedies of Lender. Furthermore,
regardless of whether or not the UCC is in effect in the jurisdiction where such
rights, powers and remedies are asserted, Lender shall have the rights, powers
and remedies of a secured party under the UCC.

     10.4 Upon payment in full of all Obligations, the Lender shall cancel the
Note, this Agreement and all UCC financing statements, if any, and shall
promptly deliver all such canceled documents to the Borrower.

     10.5 GOVERNING LAW. This Agreement, the Note and the other Loan Documents
have been negotiated and delivered to Lender in the State of Illinois and shall
not become
<PAGE>

effective until accepted by Lender in the State of Illinois. Payment to Lender
by Borrower of the Obligations is due in the State of Illinois. This Agreement
shall be governed by, and construed and enforced in accordance with the laws of
the State of Illinois excluding conflict of laws principles that would cause the
application of laws of any other jurisdiction.

     10.6  CONSENT TO JURISDICTION AND VENUE. All judicial proceedings arising
in or under or related to this Agreement, the Note or any of the other Loan
Documents may be brought in any state or federal court of competent jurisdiction
located in the State of Illinois. By execution and delivery of this Agreement,
each party hereto generally and unconditionally: (a) consents to personal
jurisdiction in Cook County, State of Illinois; (b) waives any objection as to
jurisdiction or venue in the aforesaid courts; and (d) irrevocably agrees to be
bound by any judgment rendered thereby in connection with this Agreement, the
Note an the other Loan Documents. Service of process on any party hereto in any
action arising out of or relating to this agreement shall be effective if given
in accordance with the requirements for notice set forth in subsection 10.8
below and shall be deemed effective and received as set forth in subsection 10.8
below. Nothing herein shall affect the right to serve process in any other
manner permitted by law or shall limit the right of either party to bring
proceedings in the courts of any other jurisdiction.

     10.7  Whenever possible, each provision of this Agreement shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Agreement shall be prohibited by or invalid under
such law, such provision shall be ineffective only to the extent and duration of
such prohibition or invalidity, without invalidating the remainder of such
provision or the remaining provisions of this Agreement.

     10.8  Any notice required or given hereunder shall be deemed properly
given upon the earlier of: (i) the first business day after transmission by
facsimile or hand delivery or deposit with an overnight express service or
overnight mail delivery service; or (ii) or three (3) days after mailed, postage
prepaid, in each case, addressed to the designated recipient at its address set
forth herein or such other address as such party may advise the other party by
notice given in accordance with this provision.

     10.9  Lender and Borrower acknowledge that there are no agreements or
understandings, written or oral, between Lender and Borrower with respect to the
Loan, other than as set forth herein, in the Note and the other Loan Documents
and that this Agreement, the Note and the other Loan Documents contain the
entire agreement between Lender and Borrower with respect thereto. None of the
terms of this Agreement, the Note and the other Loan Documents may be amended
except by an instrument executed by each of the parties hereto.

     10.10 No omission, or delay, by Lender at any time to enforce any right
or remedy reserved to it, or to require performance of any of the terms,
covenants or provisions hereof by Borrower at any time designated, shall be a
waiver of any such right or remedy to which Lender is entitled, nor shall it in
any way affect the right of Lender to enforce such provisions thereafter.

     10.11   All agreements, representations and warranties contained in this
Agreement or the Note, or in any Loan Documents delivered pursuant hereto or in
connection herewith shall be for the benefit of Lender and any Assignee and
shall survive the execution and delivery of this Agreement or the Note and the
expiration or other termination of this Agreement or the Note.
<PAGE>

     10.12 This Agreement may be executed in any number of counterparts,
each of which shall be deemed an original, but all such counterparts together
shall constitute but one and the same instrument.

     10.13 This Agreement shall be binding upon, and shall inure to the
benefit of, Borrower and its permitted assigns (if any). Borrower shall not
assign its obligations under this Agreement, the Note or any of the other Loan
Documents without Lender's express written consent and any such attempted
assignment shall be void and of no effect. Any assignment by Borrower in
connection with a "Merger" (as defined below) shall be subject to Lender's prior
consent. Any consent granted by Lender shall be conditioned upon such surviving
entity or transferee assuming Borrower's Obligations hereunder pursuant to
assignment documents reasonably acceptable to Lender. If Lender reasonably
withholds its consent to such assignment in connection with a Merger, the
outstanding principal and accrued and unpaid interest shall be prepaid in whole.
Lender hereby consents to any Merger in which the acquiring entity has a Moodys
Bond Rating of BA3 or better or a commercially acceptable equivalent measure of
creditworthiness as reasonably determined by Lessor. Lender's consent hereunder
will not be unreasonably delayed or conditioned.

     For purposes of this Agreement, a "Merger" shall mean any consolidation or
merger of the Borrower with or into any other corporation or entity, any sale or
conveyance of an or substantially ail of the assets or stock of the Borrower by
or to any other person or entity in which Borrower is not the surviving entity.

     IN WITNESS WHEREOF, the Borrower and the Lender have duly executed and
delivered this Agreement as of the day and year first above written.

                    BORROWER: CHORUM TECHNOLOGIES, INC.

                          By:  /s/ Scott Grout
                              -----------------------------------

                          Title:  President and CEO
                                 --------------------------------

                          Date:   9/23/98
                                 --------------------------------

ACCEPTED IN ROSEMONT, ILLINOIS:
------------------------------

                    LENDER: COMDISCO, INC.

                          By:
                              -----------------------------------

                          Title:
                                 --------------------------------

                          Date:
                                 --------------------------------
<PAGE>

                            SECURED PROMISSORY NOTE

$870,683.37                                    Date: September 30, 1998

                                               Due: October 1, 2002

FOR VALUE RECEIVED, CHORUM TECHNOLOGIES, INC. a Delaware corporation (the
"Borrower") hereby promises to pay to the order of Comdisco, Inc., a Delaware
corporation (the "Lender") at P.O. Box 91744., Chicago, IL 60693 or such other
place of payment as the holder of this Secured Promissory Note (this "Note") may
specify from time to time in writing, in lawful money of the United States of
America, the principal amount of Eight Hundred Seventy Thousand Six Hundred
Eighty-three and 37/100 Dollars ($870,683.37) together with interest at seven
and one quarter percent (7.25%) per annum from the date of this Note to maturity
of each installment on the principal hereof remaining from time to time unpaid,
such principal and interest to be paid in 48 equal monthly installments of
$20,954.93 each, commencing November 1, 1998 and on the same day of each month
thereafter to and including October 1, 2002 and an additional installment in the
amount of $130,602.51 ("Balloon Payment") to be paid on October 1, 2002, such
installments to be applied first to accrued and unpaid interest and the balance
to unpaid principal. Interest shall be computed on the basis of a year
consisting of twelve months of thirty days each.

This Note is the Note referred to in, and is executed and delivered in
connection with, that certain Loan and Security Agreement dated as of September
22, 1998 by and between Borrower and Lender (as the same may from time to time
be amended, modified or supplemented in accordance with its terms, the "Loan
Agreement"), and is entitled to the benefit and security of the Loan Agreement
and the other Loan Documents (as defined in the Loan Agreement), to which
reference is made for a statement of all of the terms and conditions thereof.
All terms defined in the Loan Agreement shall have the same definitions when
used herein, unless otherwise defined herein to the extent that the terms and
conditions in the Loan Agreement are in conflict with the terms and conditions
of this note, the terms and conditions of the Loan Agreement shall control.

The Borrower waives presentment and demand for payment, notice of dishonor,
protest and notice of protest and any other notice as permitted under the UCC or
any applicable law.

This Note has been negotiated and delivered to Lender and is payable in the
State of Illinois, and shall not become effective until accepted by Lender in
the State of Illinois. This Note shall be governed by and construed and enforced
in accordance with, the laws

NOTE DOC
<PAGE>

of the State of Illinois, excluding any conflicts of law rules or principles
that would cause the application of the laws of any other jurisdiction.

BORROWER:                   CHORUM TECHNOLOGIES, INC.
                            1155 East Collins Street, Suite 200
                            Richardson, TX 75081

                            Signature:     /s/ Scott Grout
                                      -----------------------------------

                            Print Name:   Scott Grout
                                       ----------------------------------

                            Title:    President and CEO
                                  ---------------------------------------
<PAGE>

                                   EXHIBIT 1

This Financing Statement covers the following Collateral pledged by Chorum
Technologies, Inc. ("Debtor") to Comdisco, Inc. ("Secured Party") pursuant to
the Loan and Security Agreement dated as of September 22, 1998 between Chorum
Technologies, Inc. as Borrower and Comdisco, Inc. as Lender ("Loan Agreement")
for purposes of securing payment of the Obligations (as defined in the Loan
Agreement) now and hereafter owing by Debtor to Secured Party pursuant to that
Secured Promissory Note dated September 30, 1998.

All of the Debtor's right, title and interest in: (I) the equipment and other
property (the "Equipment") described on Exhibit B attached hereto; and (ii) all
proceeds, products, replacements, additions to, substitutions for and
accessories to any and all Equipment including, without limitation, proceeds
applicable to insurance.
<PAGE>

                            EQUIPMENT SCHEDULE VL-1
                         DATED AS OF SEPTEMBER 22,1998
                           TO MASTER LEASE AGREEMENT
              DATED AS OF SEPTEMBER 22, 1998 (THE "MASTER
                                  LEASE")

LESSEE: CHORUM TECHNOLOGIES, INC.                LESSOR: COMDISCO, INC.

Admin. Contact/Phone No.:                        Address for all Notices:
------------------------                         -----------------------
Mark Kightlinger                                 6111 North River Road
(972) 238-1770                                   Rosemont, Illinois 60018
(972) 238-1477                                   Attn.: Venture Group

Address for Notices:
-------------------
1155 East Collins Blvd., Ste. 200
Richardson, TX 75081

Central Billing Location:                        Rent Interval: Monthly
------------------------                         -------------
same as above

Attn.:
Lessee Reference No.:
                      -------------------
   (24 digits maximum)

Location of Equipment: same as above             Initial Term:  48 months
---------------------                            ------------
                                                 (Number of Rent Intervals)

                                                 Lease Rate Factor: 2.392%
                                                 -----------------
Attn.:

EQUIPMENT (as defined below):                    Advance: None
                                                 -------

                                                 Interim Rent: None
                                                 ------------

Equipment specifically approved by Lessor, which shall be delivered to and
accepted by Lessee during the period September 22, 1998 through September 22,
1999 ("Equipment Delivery Period"), for which Lessor receives vendor invoices
approved for payment, up to an aggregate purchase price of $1,259,019.90
("Commitment Amount"); excluding custom use equipment, leasehold improvements,
installation costs and delivery costs, rolling stock, special tooling, "stand-
alone" software, application software bundled into computer hardware, hand held
items, molds and fungible items.
<PAGE>

1. Equipment Purchase

     This Schedule contemplates Lessor's acquisition of Equipment for lease to
Lessee, either by one of the first three categories listed below or by providing
Lessee with Equipment from the fourth category, in an aggregate value up to the
Commitment Amount referred to on the face of this Schedule. If the Equipment
acquired is of category (i), (ii) , (iii) below, the effectiveness of this
Schedule as it relates to those items of Equipment is contingent upon Lessee's
acknowledgment at the time Lessor acquires the Equipment that Lessee has either
received or approved the relevant purchase documentation between vendor and
Lessor for that Equipment.

     (i)   NEW ON-ORDER EQUIPMENT. Lessor will purchase new Equipment which is
             obtained from a vendor by Lessee for its use subject to Lessor's
             prior approval of the Equipment.

     (ii)  SALE-LEASEBACK EQUIPMENT. Any in-place Equipment installed at
             Lessee's site and to which Lessee has clear title and ownership may
             be considered by Lessor for inclusion under this Lease (the "Sale-
             Leaseback Transaction"). Any request for a Sale-Leaseback
             Transaction must be submitted to Lessor in writing (along with
             accompanying evidence of Lessee's Equipment ownership satisfactory
             to Lessor for all Equipment submitted) no later than October 22,
             1998*. Lessor will not perform a Sale-Leaseback Transaction for any
             request or accompanying Equipment ownership documents which arrive
             after the date marked above by an asterisk (*). Further, any sale-
             leaseback Equipment will be placed on lease subject to: (1) Lessor
             prior approval of the Equipment; and (2) if approved, at Lessor's
             actual net appraised Equipment value pursuant to the schedule
             below:

<TABLE>
<CAPTION>
            ORIGINAL EQUIPMENT INVOICE              PERCENT OF ORIGINAL MANUFACTURER'S
                    DATE                            NET EQUIPMENT COST PAID BY LESSOR
                                                    ---------------------------------

<S>                                                 <C>
            Between 10/22/97-10/22/98(360 days)                    100%

</TABLE>

     (iii) USED ON-ORDER EQUIPMENT. Lessor will purchase used Equipment which is
             obtained from a third party by Lessee for its use subject to
             Lessor's prior approval of the Equipment and at Lessor's appraised
             value for such used Equipment.

     (iv)  800 NUMBER EQUIPMENT. Upon Lessee's use of Comdisco's 1-800 Direct
             Service, Lessor will purchase new or used Equipment from a third
             party or Lessor will supply new or used Equipment from its
             inventory for use by Lessee at rates provided by Lessor.

2. Commencement Date

     The Commencement Date for each item of new on-order or used on-order
Equipment will be the install date as confirmed in writing by Lessee as set
forth on the vendor invoice of which a facsimile transmission will constitute an
original document. The Commencement Date for sale-leaseback Equipment shall be
the date Lessor tenders the purchase price. The Commencement Date for 800 Number
Equipment shall be fifteen (15) days from the ship date, such ship date to be
set forth on the vendor invoice or if unavailable on the vendor invoice the ship
date will be determined by Lessor upon other supporting shipping documentation.
Lessor will summarize all approved invoices, purchase documentation and evidence
of delivery, as applicable, received in the same calendar quarter into a Summary
Equipment Schedule in the form attached to this Schedule as Exhibit 1, and the
Initial Term will begin the first day of the calendar quarter thereafter. Each
Summary Equipment Schedule will contain the Equipment location, description,
serial number(s) and cost and will incorporate the terms and conditions of the
Master Lease and this Schedule and will constitute a separate lease.
<PAGE>

3.   Option to Extend

     So long as no Event of Default has occurred and is continuing hereunder,
and upon written notice no earlier than twelve (12) months and no later than
ninety (90) days prior to the expiration of the Initial Term of a Summary
Equipment Schedule, Lessee will have the right to extend the Initial Term of
such Summary Equipment Schedule for a period of one (1) year. In such event, the
rent to be paid during said extended period shall be mutually agreed upon and if
the parties cannot mutually agree within ninety (90) days of the expiration of
the Initial Term, then Lessee may revoke its election to extend the Initial Term
by notice given to Lessor within five (5) days thereafter. If such notice is not
given and an impasse is reached, then the Summary Equipment Schedule shall
continue in full force and effect pursuant to the existing terms and conditions
until terminated in accordance with its terms. The Summary Equipment Schedule
will continue in effect following said extended period until terminated by
either party upon not less than ninety (90) days prior written notice, which
notice shall be effective as of the date of receipt.

4.   Purchase Option

     So long as no Event of Default has occurred and is continuing hereunder,
and upon written notice no earlier than twelve (12) months and no later than
ninety (90) days prior to the expiration of the Initial Term or the extended
term of the applicable Summary Equipment Schedule, Lessee will have the option
at the expiration of the Initial Term or the extended term of the Summary
Equipment Schedule to purchase all, but not less than all, of the Equipment
listed therein for a purchase price not to exceed 15% of Lessor's cost hereunder
and upon terms and conditions to be mutually agreed upon by the parties
following Lessee's written notice, plus any taxes applicable at time of
purchase. Said purchase price shall be paid to Lessor on the expiration date of
the Initial Term or extended term. Title to the Equipment shall automatically
pass to Lessee upon payment in full of the purchase price but, in no event,
earlier than the expiration of the fixed Initial Term or extended term, if
applicable Notwithstanding the exercise by Lessee of this option and payment of
the purchase price, until all obligations under the applicable Summary Equipment
Schedule have been fulfilled, it is agreed and understood that Lessor shall
retain a purchase money security interest in the Equipment listed therein and
the Summary Equipment Schedule shall constitute a Security Agreement under the
Uniform Commercial Code of the state in which the Equipment is located.

If the parties are unable to agree on the purchase price or the terms and
conditions with respect to said purchase within ninety (90) days of the
expiration of the Initial Term or the renewal term, as applicable, then Lessee
may revoke its election to purchase the Equipment by notice given to Lessor
within five (5) days thereafter. If such notice is not given and an impasse is
reached, the Summary Equipment Schedule shall continue in full force and effect
pursuant to the existing terms and conditions until terminated by either party
upon not less than ninety (90) days prior written notice, which notice shall be
effective as of the date of receipt.

5.   Technology Exchange Option

     So long as no Event of Default has occurred and is continuing, and there is
no material adverse change in Lessee's credit, on or after the expiration of the
12th month of any Summary Equipment Schedule, Lessee shall have the option to
replace any of the Equipment subject to such summary Equipment Schedule with new
technology equipment ("New Technology Equipment') utilizing the following
guidelines:

A. Equipment being replaced with New Technology Equipment shall have an
aggregate original cost equal to or greater than $20,000 and be comprised of
full configurations of equipment.

B. This technology Exchange Option shall be limited to a maximum in the
aggregate of fifty percent (50%) of the original equipment cost and shall not
apply to software or any soft costs financed hereunder including but not limited
to tenant improvements and custom equipment.

C. The cost of the New Technology Equipment must be equal to or greater than the
original equipment cost of the replaced equipment, but in no event shall exceed
150% of the original equipment cost.

D. The remaining lease payments applicable to the equipment being replaced by
the New Technology Equipment will be discounted to present value at 6%.

The wholesale market value of the equipment being replaced will be established
by Comdisco based upon then current market conditions. Upon the return of the
replaced equipment, the wholesale price will be deducted from the present value
of the remaining
<PAGE>

rentals and the differential will be added to the cost of the New Technology
Equipment in calculating the new rental. The lease for the New Technology
Equipment will contain terms and conditions substantially similar to those for
the replaced equipment and will have an Initial Term not less than the balance
of the remaining Initial Term for the replaced equipment.

8.  Special Terms

    The terms and conditions of the Lease as they pertain to this Schedule are
    hereby modified and amended as follows:

    (a) Casualty Value Table is attached as Exhibit 2.

Master Lease: This Schedule is issued pursuant to the Lease identified on page 1
of this Schedule. All of the terms and conditions of the Lease are incorporated
in and made a part of this Schedule as if they were expressly set forth in this
Schedule. The parties hereby reaffirm all of the terms and conditions of the
Lease (including, without limitation, the representations and warranties set
forth in Section 8) except as modified herein by this Schedule. This Schedule
may not be amended or rescinded except by a writing signed by both parties.

CHORUM TECHNOLOGIES, INC.                        COMDISCO, INC.
as Lessee                                        as Lessor

By:    /s/ Scott Grout                           By:     /s/ James P. Labe
      ---------------------                         --------------------------

Title: President and CEO                         Title:  President
      ---------------------                            -----------------------

Date:  9/28/98                                   Date:   9/28/98
      ---------------------                           ------------------------

<PAGE>

                                   EXHIBIT  1

                           SUMMARY EQUIPMENT SCHEDULE
                           --------------------------

     This Summary Equipment Schedule dated XXXX is executed pursuant to
Equipment Schedule No. X to the Master Lease Agreement dated XXXX between
Comdisco, Inc. ("Lessor") and XXXX ("Lessee"). All of the terms, conditions,
representations and warranties of the Master Lease Agreement and Equipment
Schedule No. X are incorporated herein and made a part hereof, and this Summary
Equipment Schedule constitutes a Schedule for the Equipment on the attached
invoices.

1.   For Period Beginning:          And Ending:
     ---------------------          ----------

2.   Initial Term Starts on:        Initial Term:
     -----------------------        -------------
                                    (Number of Rent  Intervals)

3.   Total Summary Equipment Cost:
     -----------------------------

4.   Lease Rate Factor:
     ------------------

5.   Rent:
     -----

6.   Acceptance Doc Type:
     --------------------
<PAGE>

                                   EXHIBIT 2
                                   ---------

                        CASUALTY VALUE TABLE - MONTHLY

The Casualty Value applicable to an item of Equipment will be the acquisition
cost multiplied by the Casualty Value Percentage set forth below applicable to
that item.
<TABLE>
<CAPTION>
                               ------------------------------------------------------------------------------------------
                                                                                                        83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months      and beyond
                               Initial Term     Initial Term       Initial Term       Initial Term    Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
DATE OF DELIVERY
TO INITIAL TERM
START DATE                         108.0000%          108.0000%          108.0000%         108.0000%      108.0000%

YEAR ONE

1st (Month of                      108.0000           108.0000           108.0000          108.0000       108.0000
2nd Initial Term)                  106.4157           106.7446           106.9550          107.1970       107.3658
3rd                                104.8130           105.4746           105.8979          106.3846       106.7242
4th                                103.1915           104.1898           104.8284          105.5628       106.0751
5th                                101.5512           102.8899           103.7464          104.7314       105.4185
6th                                 99.8917           101.5749           102.6518          103.8902       104.7451
7th                                 98.2128           100.2446           101.5444          103.0393       104.0821
8th                                 96.5143            98.8988           100.4241          102.1784       103.4021
9th                                 94.7961            97.5372            99.2908          101.3075       102.7143
10th                                93.0578            96.1598            98.1442          100.4265       102.0184
11th                                91.2992            94.7662            96.9842           99.5351       101.3144
12th                                89.5201            93.3565            95.8107           98.6334       100.6022

YEAR TWO

1st (Month of                       87.7202            91.9303            94.6236           97.7211        99.8817
2nd Initial Term)                   85.8993            90.4874            93.4225           96.7982        99.1528
3rd                                 84.0572            89.0277            92.2075           95.8645        98.4154
4th                                 82.1936            87.5510            90.9783           94.9199        97.6694
5th                                 80.3083            86.0571            89.7347           93.9643        96.9147
6th                                 78.4009            84.5457            88.4766           92.9976        96.1511
7th                                 76.4713            83.0167            87.2039           92.0195        95.3787
8th                                 74.5192            81.4698            85.9163           91.0301        94.5972
9th                                 72.5444            79.9049            84.6137           90.0291        93.8067
10th                                70.5464            78.3218            83.2958           89.0165        93.0069
11th                                68.5252            76.7202            81.9627           87.9920        92.1978
12th                                66.4804            75.0998            80.6139           86.9556        91.3792
</TABLE>
<PAGE>

<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
YEAR THREE

1 st (Month of                      64.4117            73.4606            79.2494           85.9071        90.5511
2nd Initial Term)                   62.3189            71.8023            77.8690           84.8463        89.7133
3rd                                 60.2017            70.1246            76.4725           83.7732        88.8658
4th                                 58.0598            68.4274            75.0597           82.6876        88.0083
5th                                 55.8929            66.7103            73.6305           81.5893        87.1409
6th                                 53.7007            64.9732            72.1845           80.4781        86.2633
7th                                 51.4830            63.2159            70.7217           79.3541        85.3755
8th                                 49.2393            61.4380            69.2418           78.2169        84.4774
9th                                 46.9695            59.6394            67.7447           77.0664        83.5687
10th                                44.6732            57.8198            66.2300           75.9025        82.6495
11th                                42.3502            55.9790            64.6977           74.7251        81.7196
12th                                40.0000            54.1167            63.1476           73.5339        80.7787

YEAR FOUR

1st (Month of                       40.0000            52.2327            61.5793           72.3288        79.8270
2nd Initial Term)                   40.0000            50.3267            59.9928           71.1096        78.8641
3rd                                 40.0000            48.3985            58.3877           69.8762        77.8900
4th                                 40.0000            46.4478            56.7639           68.6284        76.9075
5th                                 40.0000            44.4743            55.1212           67.3661        75.9045
6th                                 40.0000            42.4778            53.4598           66.0891        74.8989
7th                                 40.0000            40.4580            51.7780           64.7971        73.8785
8th                                 40.0000            38.4146            50.0771           63.4901        72.8462
9th                                 40.0000            36.3474            48.3564           62.1678        71.8019
10th                                40.0000            34.2561            46.6156           60.8301        70.7454
11th                                40.0000            32.1404            44.8544           59.4768        69.6765
12th                                40.0000            30.0000            43.0728           58.1077        68.5952

YEAR FIVE

1st (Month of                                          30.0000            41.2703           56.7226        67.5013
2nd Initial Term)                                      30.0000            39.4468           55.3214        66.3946
3rd                                                    30.0000            37.6021           53.9038        65.2750
4th                                                    30.0000            35.7358           52.4697        64.1423
5th                                                    30.0000            33.8477           51.0188        62.9965
6th                                                    30.0000            31.9376           49.5511        61.8372
7th                                                    30.0000            30.0053           48.0662        60.6645
8th                                                    30.0000            28.0504           46.5639        59.4780
9th                                                    30.0000            26.0726           45.0442        58.2777
10th                                                   30.0000            24.0719           43.5067        57.0634
11th                                                   30.0000            22.0477           41.9513        55.8350
12th                                                   30.0000            20.0000           40.3777        54.5922
</TABLE>
<PAGE>

<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
YEAR SIX
1st (Month of                                                      20.0000                  38.7858        53.3349
2nd Initial Term)                                                  20.0000                  37.1753        52.0629
3rd                                                                20.0000                  35.5460        50.7761
4th                                                                20.0000                  33.8978        49.4743
5th                                                                20.0000                  32.2302        48.1573
                                                                   20.0000                  30.5433        46.8249
7th                                                                20.0000                  28.8366        45.4770
8th                                                                20.0000                  27.1100        44.1134
                                                                   20.0000                  25.3633        42.7338
10th                                                               20.0000                  23.5962        41.3382
11th                                                               20.0000                  21.8085        39.9263
12th                                                               20.0000                  20.0000        38.4979

 YEAR SEVEN

 1 st (Month of                                                                             20.0000        37.0528
 2nd Initial Term)                                                                          20.0000        35.5909
 3rd                                                                                        20.0000        34.1119
 4th                                                                                        20.0000        32.6157
 5th                                                                                        20.0000        31.1020
                                                                                            20.0000        29.5707
 7th                                                                                        20.0000        28.0214
 8th                                                                                        20.0000        26.4542
 9th                                                                                        20.0000        24.8686
 10th                                                                                       20.0000        23.2645
 11th                                                                                       20.0000        21.6417
 12th                                                                                       20.0000        *20.0000
                                                                                            * Applicable Thereafter
</TABLE>
<PAGE>

                      EQUIPMENT SCHEDULE VL-2
                     DATED AS OF SEPTEMBER 22,1998
                      TO MASTER LEASE AGREEMENT
              DATED AS OF SEPTEMBER 22, 1998 (THE "MASTER LEASE")

LESSEE: CHORUM TECHNOLOGIES, INC.               LESSOR: COMDISCO, INC.

Admin. Contact/Phone No.:                       Address for all Notices:
------------------------                        -----------------------
Mark Kightlinger                                6111 North River Road
(972) 238-1770                                  Rosemont, Illinois 60018
(972) 238-1477Fax                               Attn: Venture Group
Address for Notices:
-------------------
1155 East Collins Blvd., Ste 200
Richardson, TX 75081

Central Billing Location:                       Rent Interval: Monthly
------------------------                        -------------
same as above

Attn:
Lessee Reference No.:
     (24 digits maximum)

Location of Equipment:                          Initial Term: 48 months
---------------------                           ------------
                                                (Number of Rent Intervals)

                                                Lease Rate Factor: 2.392%
                                                -----------------

Attn:

EQUIPMENT (as defined below):                   Advance: None
                                                -------
                                                Interim Rent: None
                                                ------------

     Software (including maintenance fees) and tenant improvements specifically
approved by Lessor, which shall be delivered to and accepted by Lessee during
the period September 22, 1998 through September 22, 1999 ("Equipment Delivery
Period") for which Lessor receives vendor invoices approved for payment, up to
an aggregate purchase price of $370,296.73("Commitment Amount').
<PAGE>

1.   Equipment Purchase

     This Schedule contemplates Lessor's acquisition of Equipment for lease to
Lessee, either by one of the first three categories listed below or by providing
Lessee with Equipment from the fourth category, in an aggregate value up to the
Commitment Amount referred to on the face of this Schedule. If the Equipment
acquired is of category (i), (ii) , (iii) below, the effectiveness of this
Schedule as it relates to those items of Equipment is contingent upon Lessee's
acknowledgment at the time Lessor acquires the Equipment that Lessee has either
received or approved the relevant purchase documentation between vendor and
Lessor for that Equipment.

     (i)     NEW ON-ORDER EQUIPMENT. Lessor will purchase new Equipment which is
             obtained from a vendor by Lessee for its use subject to Lessor's
             prior approval of the Equipment.

     (ii)    SALE-LEASEBACK EQUIPMENT. Any in-place Equipment installed at
             Lessee's site and to which Lessee has clear title and ownership may
             be considered by Lessor for inclusion under this Lease (the "Sale-
             Leaseback Transaction"). Any request for a Sale-Leaseback
             Transaction must be submitted to Lessor in writing (along with
             accompanying evidence of Lessee's Equipment ownership satisfactory
             to Lessor for all Equipment submitted) no later than October 22,
             1998*. Lessor will not perform a Sale-Leaseback Transaction for any
             request or accompanying Equipment ownership documents which arrive
             after the date marked above by an asterisk (*). Further, any sale-
             leaseback Equipment will be placed on lease subject to: (1) Lessor
             prior approval of the Equipment; and (2) if approved, at Lessor's
             actual net appraised Equipment value pursuant to the schedule
             below:

             ORIGINAL EQUIPMENT INVOICE       PERCENT OF ORIGINAL MANUFACTURER'S
                       DATE                   NET EQUIPMENT COST PAID BY LESSOR
                                              ---------------------------------

             Between 10/22/97-10/22/98 (360 days)             100%

     (iii)   USED ON-ORDER EQUIPMENT. Lessor will purchase used Equipment which
             is obtained from a third party by Lessee for its use subject to
             Lessor's prior approval of the Equipment and at Lessor's appraised
             value for such used Equipment.

     (iv)    800 NUMBER EQUIPMENT. Upon Lessee's use of Comdisco's 1-800 Direct
             Service, Lessor will purchase new or used Equipment from a third
             party or Lessor will supply new or used Equipment from its
             inventory for use by Lessee at rates provided by Lessor.

2.   Commencement  Date

     The Commencement Date for each item of new on-order or used on-order
Equipment will be the install date as confirmed in writing by Lessee as set
forth on the vendor invoice of which a facsimile transmission will constitute an
original document. The Commencement Date for sale-leaseback Equipment shall be
the date Lessor tenders the purchase price. The Commencement Date for 800 Number
Equipment shall be fifteen (15) days from the ship date, such ship date to be
set forth on the vendor invoice or if unavailable on the vendor invoice the ship
date will be determined by Lessor upon other supporting shipping documentation.
Lessor will summarize all approved invoices, purchase documentation and evidence
of delivery, as applicable, received in the same calendar quarter into a Summary
Equipment Schedule in the form attached to this Schedule as Exhibit 1, and the
Initial Term will begin the first day of the calendar quarter thereafter. Each
Summary Equipment Schedule will contain the Equipment location, description,
serial number(s) and cost and will incorporate the terms and conditions of the
Master Lease and this Schedule and will constitute a separate lease.

3.   Miscellaneous

     In consideration of Lessor financing software and tenant improvements
hereunder, Lessee agrees in addition to its last Monthly Rent Payment to remit
to Lessor an amount equal to 15% of Lessor's aggregate cost of software and
tenant improvements provided hereunder.

4.   Special Terms

     The terms and conditions of the Lease as they pertain to this Schedule are
hereby modified and amended as follows:
<PAGE>

          (a)    Section 9, Delivery and Return of Equipment
                 -------------------------------------------

          Delete second, third and fourth sentences in their entirety.

          (b)    Casualty Value Table is attached as Exhibit 2.

     Master Lease: This Schedule is issued pursuant to the Lease identified on
     page 1 of this Schedule. All of the terms and conditions of the Lease are
     incorporated in and made a part of this Schedule as if they were expressly
     set forth in this Schedule. The parties hereby reaffirm all of the terms
     and conditions of the Lease (including, without limitation, the
     representations and warranties set forth in Section 8) except as modified
     herein by this Schedule. This Schedule may not be amended or rescinded
     except by a writing signed by both parties.

          CHORUM TECHNOLOGIES, INC.               COMDISCO, INC.
          as Lessee                               as Lessor

          By:    /s/ Scott Grout                  By:     /s/ James P. Labe
             -------------------------               ------------------------

          Title: President and CEO                Title:  President
                ----------------------                  ---------------------

          Date:       9/23/98                     Date:   9/28/98
               -----------------------                -----------------------
<PAGE>

                                   EXHIBIT 1

                          SUMMARY EQUIPMENT SCHEDULE
                          --------------------------

     This Summary Equipment Schedule dated XXXX is executed pursuant to
Equipment Schedule No. X to the Master Lease Agreement dated XXXX between
Comdisco, Inc. ("Lessor") and XXXX ("Lessee"). All of the terms, conditions,
representations and warranties of the Master Lease Agreement and Equipment
Schedule No. X are incorporated herein and made a part hereof, and this Summary
Equipment Schedule constitutes a Schedule for the Equipment on the attached
invoices.

1.   For Period Beginning:          And Ending:
     ---------------------          -----------

2.   Initial Term Starts on:        Initial Term:
     -----------------------        -------------
                                    (Number of Rent Intervals)

3.   Total Summary Equipment Cost:
     -----------------------------

4.   Lease Rate Factor:
     ------------------

5.   Rent:
     -----

6.   Acceptance Doc Type:
     --------------------
<PAGE>

                                   EXHIBIT 2
                                   ---------

                        CASUALTY VALUE TABLE - MONTHLY

The Casualty Value applicable to an item of Equipment will be the acquisition
cost multiplied by the Casualty Value Percentage set forth below applicable to
that item.
<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term       Initial Term    Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>

DATE OF DELIVERY
TO INITIAL TERM
START DATE                         108.0000%          108.0000%          108.0000%         108.0000%      108.0000%

YEAR ONE

1st (Month of                      108.0000           108.0000           108.0000          108.0000       108.0000
2nd Initial Term)                  106.4157           106.7446           106.9550          107.1970       107.3658
3rd                                104.8130           105.4746           105.8979          106.3846       106.7242
4th                                103.1915           104.1898           104.8284          105.5628       106.0751
5th                                101.5512           102.8899           103.7464          104.7314       105.4185
6th                                 99.8917           101.5749           102.6518          103.8902       104.7451
7th                                 98.2128           100.2446           101.5444          103.0393       104.0821
8th                                 96.5143            98.8988           100.4241          102.1784       103.4021
9th                                 94.7961            97.5372            99.2908          101.3075       102.7143
10th                                93.0578            96.1598            98.1442          100.4265       102.0184
11th                                91.2992            94.7662            96.9842           99.5351       101.3144
12th                                89.5201            93.3565            95.8107           98.6334       100.6022

YEAR TWO

1st (Month of                       87.7202            91.9303            94.6236           97.7211        99.8817
2nd Initial Term)                   85.8993            90.4874            93.4225           96.7982        99.1528
3rd                                 84.0572            89.0277            92.2075           95.8645        98.4154
4th                                 82.1936            87.5510            90.9783           94.9199        97.6694
5th                                 80.3083            86.0571            89.7347           93.9643        96.9147
6th                                 78.4009            84.5457            88.4766           92.9976        96.1511
7th                                 76.4713            83.0167            87.2039           92.0195        95.3787
8th                                 74.5192            81.4698            85.9163           91.0301        94.5972
9th                                 72.5444            79.9049            84.6137           90.0291        93.8067
10th                                70.5464            78.3218            83.2958           89.0165        93.0069
11th                                68.5252            76.7202            81.9627           87.9920        92.1978
12th                                66.4804            75.0998            80.6139           86.9556        91.3792
</TABLE>
<PAGE>

<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
YEAR THREE

1st (Month of                       64.4117            73.4606            79.2494           85.9071        90.5511
2nd Initial Term)                   62.3189            71.8023            77.8690           84.8463        89.7133
3rd                                 60.2017            70.1246            76.4725           83.7732        88.8658
4th                                 58.0598            68.4274            75.0597           82.6876        88.0083
5th                                 55.8929            66.7103            73.6305           81.5893        87.1409
6th                                 53.7007            64.9732            72.1845           80.4781        86.2633
7th                                 51.4830            63.2159            70.7217           79.3541        85.3755
8th                                 49.2393            61.4380            69.2418           78.2169        84.4774
9th                                 46.9695            59.6394            67.7447           77.0664        83.5687
10th                                44.6732            57.8198            66.2300           75.9025        82.6495
11th                                42.3502            55.9790            64.6977           74.7251        81.7196
12th                                40.0000            54.1167            63.1476           73.5339        80.7787

YEAR FOUR

1 st (Month of                      40.0000            52.2327            61.5793           72.3288        79.8270
2nd Initial Term)                   40.0000            50.3267            59.9928           71.1096        78.8641
3rd                                 40.0000            48.3985            58.3877           69.8762        77.8900
4th                                 40.0000            46.4478            56.7639           68.6284        76.9075
5th                                 40.0000            44.4743            55.1212           67.3661        75.9045
6th                                 40.0000            42.4778            53.4598           66.0891        74.8989
7th                                 40.0000            40.4580            51.7780           64.7971        73.8785
8th                                 40.0000            38.4146            50.0771           63.4901        72.8462
9th                                 40.0000            36.3474            48.3564           62.1678        71.8019
10th                                40.0000            34.2561            46.6156           60.8301        70.7454
11th                                40.0000            32.1404            44.8544           59.4768        69.6765
12th                                40.0000            30.0000            43.0728           58.1077        68.5952

YEAR FIVE

1st (Month of                                          30.0000            41.2703           56.7226        67.5013
2nd Initial Term)                                      30.0000            39.4468           55.3214        66.3946
3rd                                                    30.0000            37.6021           53.9038        65.2750
4th                                                    30.0000            35.7358           52.4697        64.1423
5th                                                    30.0000            33.8477           51.0188        62.9965
6th                                                    30.0000            31.9376           49.5511        61.8372
7th                                                    30.0000            30.0053           48.0662        60.6645
8th                                                    30.0000            28.0504           46.5639        59.4780
9th                                                    30.0000            26.0726           45.0442        58.2777
10th                                                   30.0000            24.0719           43.5067        57.0634
11th                                                   30.0000            22.0477           41.9513        55.8350
12th                                                   30.0000            20.0000           40.3777        54.5922
</TABLE>
<PAGE>

<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
YEAR SIX

1st (Month of                                                             20.0000           38.7858        53.3349
2nd Initial Term)                                                         20.0000           37.1753        52.0629
3rd                                                                       20.0000           35.5460        50.7761
4th                                                                       20.0000           33.8978        49.4743
5th                                                                       20.0000           32.2302        48.1573
6th                                                                       20.0000           30.5433        46.8249
                                                                          20.0000           28.8366        45.4770
8th                                                                       20.0000           27.1100        44.1134
9th                                                                       20.0000           25.3633        42.7338
loth                                                                      20.0000           23.5962        41.3382
11th                                                                      20.0000           21.8085        39.9263
12th                                                                      20.0000           20.0000        38.4979

YEAR SEVEN

 1 st (Month of                                                                             20.0000        37.0528
 2nd Initial Term)                                                                          20.0000        35.5909
 3rd                                                                                        20.0000        34.1119
 4th                                                                                        20.0000        32.6157
 5th                                                                                        20.0000        31.1020
 6th                                                                                        20.0000        29.5707
 7th                                                                                        20.0000        28.0214
 8th                                                                                        20.0000        26.4542
 9th                                                                                        20.0000        24.8686
 10th                                                                                       20.0000        23.2645
 11th                                                                                       20.0000        21.6417
 12th                                                                                       20.0000       *20.0000
                                                                                            * Applicable Thereafter
</TABLE>
<PAGE>

                            EQUIPMENT SCHEDULE VL-3
                         DATED AS OF JANUARY 22, 1999
                           TO MASTER LEASE AGREEMENT
              DATED AS OF SEPTEMBER 22, 1998 (THE "MASTER LEASE")

LESSEE: CHORUM TECHNOLOGIES, INC.               LESSOR: COMDISCO, INC.

Admin. Contact/Phone No.:                       Address for all Notices:
------------------------                        -----------------------
Mark Kightlinger                                6111 North River Road
(972) 238-1770                                  Rosemont, Illinois 60018
(972) 238-1477                                  Attn.: Venture Group

Address for Notices:
-------------------
1155 East Collins Blvd., Ste. 200
Richardson, TX 75081

Central Billing Location:                       Rent Interval: Monthly
------------------------                        -------------
same as above

Attn.:

Lessee Reference No.:
(24 digits maximum)

Location of Equipment:                          Initial Term: 48 months
---------------------                           ------------
same as above                                   (Number of Rent Intervals)

                                                Lease Rate Factor: 2.425%
                                                -----------------
Attn.:

EQUIPMENT (as defined below):                   Advance: None
                                                -------

                                                Interim Rent: None
                                                ------------

Equipment specifically approved by Lessor, which shall be delivered to and
accepted by Lessee during the period January 22, 1999 through January 22, 2000
("Equipment Delivery Period"), for which Lessor receives vendor invoices
approved for payment, up to an aggregate purchase price of $4,600,000.00
("Commitment Amount'); excluding custom use equipment, leasehold improvements,
installation costs and delivery costs, rolling stock, special tooling, "stand-
alone" software, application software bundled into computer hardware, hand held
items, molds and fungible items.
<PAGE>

1.   Equipment Purchase

     This Schedule contemplates Lessor's acquisition of Equipment for lease to
Lessee, either by one of the first three categories listed below or by providing
Lessee with Equipment from the fourth category, in an aggregate value up to the
Commitment Amount referred to on the face of this Schedule. If the Equipment
acquired is of category (i), (ii) , (iii) below, the effectiveness of this
Schedule as it relates to those items of Equipment is contingent upon Lessee's
acknowledgment at the time Lessor acquires the Equipment that Lessee has either
received or approved the relevant purchase documentation between vendor and
Lessor for that Equipment.

     (i)     NEW ON-ORDER EQUIPMENT. Lessor will purchase new Equipment which is
             obtained from a vendor by Lessee for its use subject to Lessor's
             prior approval of the Equipment.

     (ii)    SALE-LEASEBACK EQUIPMENT. Any in-place Equipment installed at
             Lessee's site and to which Lessee has clear title and ownership may
             be considered by Lessor for inclusion under this Lease (the "Sale-
             Leaseback Transaction"). Any request for a Sale-Leaseback
             Transaction must be submitted to Lessor in writing (along with
             accompanying evidence of Lessee's Equipment ownership satisfactory
             to Lessor for all Equipment submitted) no later than February 22,
             1999 *. Lessor will not perform a Sale-Leaseback Transaction for
             any request or accompanying Equipment ownership documents which
             arrive after the date marked above by an asterisk (*). Further, any
             sale-leaseback Equipment will be placed on lease subject to: (1)
             Lessor prior approval of the Equipment; and (2) if approved, at
             Lessor's actual net appraised Equipment value pursuant to the
             schedule below:

     ORIGINAL EQUIPMENT INVOICE         PERCENT OF ORIGINAL MANUFACTURER'S
                DATE                    NET EQUIPMENT COST PAID BY LESSOR
                ----                    ---------------------------------

     Between 10/24/98 - 01 /22/99 (90 days)            100%

     (iii)   USED ON-ORDER EQUIPMENT. Lessor will purchase used Equipment which
             is obtained from a third party by Lessee for its use subject to
             Lessor's prior approval of the Equipment and at Lessor's appraised
             value for such used Equipment.

     (iv)    800 NUMBER EQUIPMENT. Upon Lessee's use of Comdisco's 1-800 Direct
             Service, Lessor will purchase new or used Equipment from a third
             party or Lessor will supply new or used Equipment from its
             inventory for use by Lessee at rates provided by Lessor.

2.   Commencement Date

     The Commencement Date for each item of new on-order or used on-order
Equipment will be the install date as confirmed in writing by Lessee as set
forth on the vendor invoice of which a facsimile transmission will constitute an
original document. The Commencement Date for sale-leaseback Equipment shall be
the date Lessor tenders the purchase price. The Commencement Date for 800 Number
Equipment shall be fifteen (15) days from the ship date, such ship date to be
set forth on the vendor invoice or if unavailable on the vendor invoice the ship
date will be determined by Lessor upon other supporting shipping documentation.
Lessor will summarize all approved invoices, purchase documentation and evidence
of delivery, as applicable, received in the same calendar month into a Summary
Equipment Schedule in the form attached to this Schedule as Exhibit 1, and the
Initial Term will begin the first day of the calendar month thereafter. Each
Summary Equipment Schedule will contain the Equipment location, description,
serial number(s) and cost and will incorporate the terms and conditions of the
Master Lease and this Schedule and will constitute a separate lease.
<PAGE>

3.   Option to Extend

     So long as no Event of Default has occurred and is continuing hereunder,
and upon written notice no earlier than twelve (12) months and no later than
ninety (90) days prior to the expiration of the Initial Term of a Summary
Equipment Schedule, Lessee will have the right to extend the Initial Term of
such Summary Equipment Schedule for a period of one (1) year. In such event, the
rent to be paid during said extended period shall be mutually agreed upon and if
the parties cannot mutually agree within ninety (90) days of the expiration of
the Initial Term, then Lessee may revoke its election to extend the Initial Term
by notice given to Lessor within five (5) days thereafter. If such notice is not
given and an impasse is reached, then the Summary Equipment Schedule shall
continue in full force and effect pursuant to the existing terms and conditions
until terminated in accordance with its terms. The Summary Equipment Schedule
will continue in effect following said extended period until terminated by
either party upon not less than ninety (90) days prior written notice, which
notice shall be effective as of the date of receipt.

4.   Purchase Option

     So long as no Event of Default has occurred and is continuing hereunder,
and upon written notice no earlier than twelve (12) months and no later than
ninety (90) days prior to the expiration of the Initial Term or the extended
term of the applicable Summary Equipment Schedule, Lessee will have the option
at the expiration of the Initial Term or the extended term of the Summary
Equipment Schedule to purchase all, but not less than all, of the Equipment
listed therein for a purchase price not to exceed 15% of Lessor's cost hereunder
and upon terms and conditions to be mutually agreed upon by the parties
following Lessee's written notice, plus any taxes applicable at time of
purchase. Said purchase price shall be paid to Lessor on the expiration date of
the Initial Term or extended term. Title to the Equipment shall automatically
pass to Lessee upon payment in full of the purchase price but, in no event,
earlier than the expiration of the fixed Initial Term or extended term, if
applicable Notwithstanding the exercise by Lessee of this option and payment of
the purchase price, until all obligations under the applicable Summary Equipment
Schedule have been fulfilled, it is agreed and understood that Lessor shall
retain a purchase money security interest in the Equipment listed therein and
the Summary Equipment Schedule shall constitute a Security Agreement under the
Uniform Commercial Code of the state in which the Equipment is located.

If the parties are unable to agree on the purchase price or the terms and
conditions with respect to said purchase within ninety (90) days of the
expiration of the Initial Term or the renewal term, as applicable, then Lessee
may revoke its election to purchase the Equipment by notice given to Lessor
within five (5) days thereafter. If such notice is not given and an impasse is
reached, the Summary Equipment Schedule shall continue in full force and effect
pursuant to the existing terms and conditions until terminated by either party
upon not less than ninety (90) days prior written notice, which notice shall be
effective as of the date of receipt.

5.   Technology Exchange Option

     So long as no Event of Default has occurred and is continuing, and there is
no material adverse change in Lessee's credit, on or after the expiration of the
12th month of any Summary Equipment Schedule, Lessee shall have the option to
replace any of the Equipment subject to such summary Equipment Schedule with new
technology equipment ("New Technology Equipment") utilizing the following
guidelines:

A. Equipment being replaced with New Technology Equipment shall have an
aggregate original cost equal to or greater than $20,000 and be comprised of
full configurations of equipment.

B. This technology Exchange Option shall be limited to a maximum in the
aggregate of fifty percent (50%) of the original equipment cost and shall not
apply to software or any soft costs financed hereunder including but not limited
to tenant improvements and custom equipment.

C. The cost of the New Technology Equipment must be equal to or greater than the
original equipment cost of the replaced equipment, but in no event shall exceed
150% of the original equipment cost.

D. The remaining lease payments applicable to the equipment being replaced by
the New Technology Equipment will be discounted to present value at 6%.

The wholesale market value of the equipment being replaced will be established
by Comdisco based upon then current market conditions. Upon the return of the
replaced equipment, the wholesale price will be deducted from the present value
of the remaining
<PAGE>

rentals and the differential will be added to the cost of the New Technology
Equipment in calculating the new rental. The lease for the New Technology
Equipment will contain terms and conditions substantially similar to those for
the replaced equipment and will have an Initial Term not less than the balance
of the remaining Initial Term for the replaced equipment.

8.  Special Terms

     The terms and conditions of the Lease as they pertain to this Schedule are
     hereby modified and amended as follows:

          (a)  Casualty Value Table is attached as Exhibit 2.

Master Lease: This Schedule is issued pursuant to the Lease identified on page 1
of this Schedule. All of the terms and conditions of the Lease are incorporated
in and made a part of this Schedule as if they were expressly set forth in this
Schedule. The parties hereby reaffirm all of the terms and conditions of the
Lease (including, without limitation, the representations and warranties set
forth in Section 8) except as modified herein by this Schedule. This Schedule
may not be amended or rescinded except by a writing signed by both parties.

          CHORUM TECHNOLOGIES, INC.             COMDISCO, INC.
          as Lessee                             as Lessor

          By:     /s/ Scott Grout               By:    /s/ Jill C. Hanses
             --------------------------            ---------------------------

          Title:  President and CEO             Title: Senior Vice President
                -----------------------               ------------------------

          Date:       11/25/98                  Date:        11/28/98
               ------------------------              -------------------------
<PAGE>

                                   EXHIBIT 1

                          SUMMARY EQUIPMENT SCHEDULE
                          --------------------------

     This Summary Equipment Schedule dated XXXX is executed pursuant to
Equipment Schedule No. X to the Master Lease Agreement dated XXXX between
Comdisco, Inc. ("Lessor") and XXXX ("Lessee"). All of the terms, conditions,
representations and warranties of the Master Lease Agreement and Equipment
Schedule No. X are incorporated herein and made a part hereof, and this Summary
Equipment Schedule constitutes a Schedule for the Equipment on the attached
invoices.

1.   For Period Beginning:          And Ending:
     ---------------------          -----------

2.   Initial Term Starts on:        Initial Term:
     -----------------------        -------------
                                    (Number of Rent Intervals)

3.   Total Summary Equipment Cost:
     -----------------------------

4.   Lease Rate Factor:
     ------------------

5.   Rent:
     -----

6.   Acceptance Doc Type:
     --------------------
<PAGE>

                            EQUIPMENT SCHEDULE VL-4
                         DATED AS OF JANUARY 22, 1999
                           TO MASTER LEASE AGREEMENT
              DATED AS OF SEPTEMBER 22, 1998 (THE "MASTER LEASE")

LESSEE: CHORUM TECHNOLOGIES, INC.               LESSOR: COMDISCO, INC.

Admin. Contact/Phone No.:                       Address for all Notices:
------------------------                        -----------------------
Mark Kightlinger                                6111 North River Road
(972) 238-1770                                  Rosemont, Illinois 60018
(972) 238-1477Fax                               Attn.: Venture Group
Address for Notices:
-------------------
1155 East Collins Blvd., Ste 200
Richardson, TX 75081

Central Billing Location:                       Rent Interval: Monthly
------------------------                        -------------
same as above

Attn.:

Lessee Reference No.: ___________
     (24 digits maximum)

Location of Equipment:
---------------------
                                                Initial Term: 36 months
                                                ------------
                                                (Number of Rent Intervals)

                                                Lease Rate Factor: 3.145%
                                                -----------------
Attn.:

EQUIPMENT (as defined below):
                                                Advance: None
                                                -------
                                                Interim Rent: None
                                                ------------

     Software(including maintenance fees) and tenant improvements specifically
approved by Lessor, which shall be delivered to and accepted by Lessee during
the period January 22, 1999 through January 22, 2000 ("Equipment Delivery
Period") for which Lessor receives vendor invoices approved for payment, up to
an aggregate purchase price of $400,000.00("Commitment Amount'), excluding
custom use equipment, installation costs and delivery costs, rolling stock,
special tooling, hand held items, molds and fungible items.

<PAGE>

1.   Equipment Purchase

     This Schedule contemplates Lessor's acquisition of Equipment for lease to
Lessee, either by one of the first three categories listed below or by providing
Lessee with Equipment from the fourth category, in an aggregate value up to the
Commitment Amount referred to on the face of this Schedule. If the Equipment
acquired is of category (i), (ii) , (iii) below, the effectiveness of this
Schedule as it relates to those items of Equipment is contingent upon Lessee's
acknowledgment at the time Lessor acquires the Equipment that Lessee has either
received or approved the relevant purchase documentation between vendor and
Lessor for that Equipment.

     (i)     NEW ON-ORDER EQUIPMENT. Lessor will purchase new Equipment which is
             obtained from a vendor by Lessee for its use subject to Lessor's
             prior approval of the Equipment.

     (ii)    SALE-LEASEBACK EQUIPMENT. Any in-place Equipment installed at
             Lessee's site and to which Lessee has clear title and ownership may
             be considered by Lessor for inclusion under this Lease (the "Sale-
             Leaseback Transaction"). Any request for a Sale-Leaseback
             Transaction must be submitted to Lessor in writing (along with
             accompanying evidence of Lessee's Equipment ownership satisfactory
             to Lessor for all Equipment submitted) no later than February 22,
             1999 *. Lessor will not perform a Sale-Leaseback Transaction for
             any request or accompanying Equipment ownership documents which
             arrive after the date marked above by an asterisk (*).

             Further, any sale-leaseback Equipment will be placed on lease
             subject to: (1) Lessor prior approval of the Equipment; and (2) if
             approved, at Lessor's actual net appraised Equipment value pursuant
             to the schedule below:

             ORIGINAL EQUIPMENT INVOICE     PERCENT OF ORIGINAL MANUFACTURER'S
                      DATE                   NET EQUIPMENT COST PAID BY LESSOR
                      ----                   ---------------------------------

          Between 10/24/98 - 01 /22/99 (90 days)            100%

     (iii)   USED ON-ORDER EQUIPMENT. Lessor will purchase used Equipment which
             is obtained from a third party by Lessee for its use subject to
             Lessor's prior approval of the Equipment and at Lessor's appraised
             value for such used Equipment.

     (iv)    800 NUMBER EQUIPMENT. Upon Lessee's use of Comdisco's 1-800 Direct
             Service, Lessor will purchase new or used Equipment from a third
             party or Lessor will supply new or used Equipment from its
             inventory for use by Lessee at rates provided by Lessor.

2.   Commencement Date

     The Commencement Date for each item of new on-order or used on-order
Equipment will be the install date as confirmed in writing by Lessee as set
forth on the vendor invoice of which a facsimile transmission will constitute an
original document. The Commencement Date for sale-leaseback Equipment shall be
the date Lessor tenders the purchase price. The Commencement Date for 800 Number
Equipment shall be fifteen (15) days from the ship date, such ship date to be
set forth on the vendor invoice or if unavailable on the vendor invoice the ship
date will be determined by Lessor upon other supporting shipping documentation.
Lessor will summarize all approved invoices, purchase documentation and evidence
of delivery, as applicable, received in the same calendar month into a Summary
Equipment Schedule in the form attached to this Schedule as Exhibit 1, and the
Initial Term will begin the first day of the calendar month thereafter. Each
Summary Equipment Schedule will contain the Equipment location, description,
serial number(s) and cost and will incorporate the terms and conditions of the
Master Lease and this Schedule and will constitute a separate lease.

3.   Miscellaneous

     In consideration of Lessor financing software and tenant improvements
hereunder, Lessee agrees in addition to its last Monthly Rent Payment to remit
to Lessor an amount equal to 15% of Lessor's aggregate cost of software and
tenant improvements provided hereunder.
<PAGE>

4.   Special Terms

     The terms and conditions of the Lease as they pertain to this Schedule are
hereby modified and amended as follows:

     (a)     Section 9, Delivery and Return of Equipment
             -------------------------------------------

     Delete second, third and fourth sentences in their entirety.

     (b)     Casualty Value Table is attached as Exhibit 2.

Master Lease: This Schedule is issued pursuant to the Lease identified on page 1
of this Schedule. All of the terms and conditions of the Lease are incorporated
in and made a part of this Schedule as if they were expressly set forth in this
Schedule. The parties hereby reaffirm all of the terms and conditions of the
Lease (including, without limitation, the representations and warranties set
forth in Section 8) except as modified herein by this Schedule. This Schedule
may not be amended or rescinded except by a writing signed by both parties.

             CHORUM TECHNOLOGIES, INC.          COMDISCO, INC.
             as Lessee                          as Lessor

             By:    /s/ Scott Grout             By:    /s/ Jill C. Hanses
                ------------------------           ---------------------------

             Title: President and CEO           Title: Senior Vice President
                   ---------------------              ------------------------

             Date:      1/25/98                 Date:        1/28/98
                  ----------------------             -------------------------
<PAGE>

                                   EXHIBIT 1

                          SUMMARY EQUIPMENT SCHEDULE
                          --------------------------

     This Summary Equipment Schedule dated XXXX is executed pursuant to
Equipment Schedule No. X to the Master Lease Agreement dated XXXX between
Comdisco, Inc. ("Lessor") and XXXX ("Lessee"). All of the terms, conditions,
representations and warranties of the Master Lease Agreement and Equipment
Schedule No. X are incorporated herein and made a part hereof, and this Summary
Equipment Schedule constitutes a Schedule for the Equipment on the attached
invoices.

1.   For Period Beginning:          And Ending:
     ---------------------          -----------

2.   Initial Term Starts on:        Initial Term:
     -----------------------        -------------
                                    (Number of Rent Intervals)

3.   Total Summary Equipment Cost:
     -----------------------------

4.   Lease Rate Factor:
     ------------------

5.   Rent:
     -----

6.   Acceptance Doc Type:
     --------------------
<PAGE>

                            EQUIPMENT SCHEDULE VL-5
                           DATED AS OF MARCH 1, 2000
                           TO MASTER LEASE AGREEMENT
              DATED AS OF SEPTEMBER 22, 1998 (THE "MASTER LEASE")

LESSEE: CHORUM TECHNOLOGIES, INC.               LESSOR: COMDISCO, INC.

Admin. Contact/Phone No.:                       Address for all Notices:
------------------------                        -----------------------
Mark Kightlinger                                6111 North River Road
Phone: 214-570-3530                             Rosemont, Illinois 60018
Fax: 214-570-3552                               Attn.: Venture Group

Address for Notices:
-------------------
1155 East Collins Blvd., Ste. 200
Richardson, TX 75081

Central Billing Location:                       Rent Interval: Monthly
------------------------                        -------------
same as above

Attn.:

Lessee Reference No.:
(24 digits maximum)

Location of Equipment:                          Initial Term: 48 months
---------------------                           ------------
1) same as above                                (Number of Rent Intervals)
2) 1303 East Arapaho
  Richardson, TX 75081

                                                Lease Rate Factor: 2.436%
                                                -----------------
Attn.:

EQUIPMENT (as defined below):                   Advance:       NONE

                                                Interim Rent:  NONE

Equipment specifically approved by Lessor, which shall be delivered to and
accepted by Lessee during the period March 1, 2000 through September 1, 2001
("Equipment Delivery Period"), for which Lessor receives vendor invoices
approved for payment, up to an aggregate purchase price of $6,400,000.00
("Commitment Amount'); excluding custom use equipment, leasehold improvements,
installation costs and delivery costs, rolling stock, special tooling, "stand-
alone" software, application software bundled into computer hardware, hand held
items, molds and fungible items.
<PAGE>

1.   Equipment Purchase

     This Schedule contemplates Lessor's acquisition of Equipment for lease to
Lessee, either by one of the first three categories listed below or by providing
Lessee with Equipment from the fourth category, in an aggregate value up to the
Commitment Amount referred to on the face of this Schedule. If the Equipment
acquired is of category (i), (ii) , (iii) below, the effectiveness of this
Schedule as it relates to those items of Equipment is contingent upon Lessee's
acknowledgment at the time Lessor acquires the Equipment that Lessee has either
received or approved the relevant purchase documentation between vendor and
Lessor for that Equipment.

     (i)     NEW ON-ORDER EQUIPMENT. Lessor will purchase new Equipment which is
             obtained from a vendor by Lessee for its use subject to Lessor's
             prior approval of the Equipment.

     (ii)    SALE-LEASEBACK EQUIPMENT. Any in-place Equipment installed at
             Lessee's site and to which Lessee has clear title and ownership may
             be considered by Lessor for inclusion under this Lease (the "Sale-
             Leaseback Transaction"). Any request for a Sale-Leaseback
             Transaction must be submitted to Lessor in writing (along with
             accompanying evidence of Lessee's Equipment ownership satisfactory
             to Lessor for all Equipment submitted) no later than April 1,
             2000*. Lessor will not perform a Sale-Leaseback Transaction for any
             request or accompanying Equipment ownership documents which arrive
             after the date marked above by an asterisk (*). Further, any sale
             leaseback Equipment will be placed on lease subject to: (1) Lessor
             prior approval of the Equipment; and (2) if approved, at Lessor's
             actual net appraised Equipment value pursuant to the schedule
             below:

             ORIGINAL EQUIPMENT INVOICE      PERCENT OF ORIGINAL MANUFACTURER'S
                        DATE                 NET EQUIPMENT COST PAID BY LESSOR
                        ----                 ---------------------------------

          Between 12/03/99 - 04/01/00 (120 days)            100%

     (iii)   USED ON-ORDER EQUIPMENT. Lessor will purchase used Equipment which
             is obtained from a third party by Lessee for its use subject to
             Lessor's prior approval of the Equipment and at Lessor's appraised
             value for such used Equipment.

     (iv)    800 NUMBER EQUIPMENT. Upon Lessee's use of Comdisco's 1-800 Direct
             Service, Lessor will purchase new or used Equipment from a third
             party or Lessor will supply new or used Equipment from its
             inventory for use by Lessee at rates provided by Lessor.

2.   Commencement Date

     The Commencement Date for each item of new on-order or used on-order
Equipment will be the install date as confirmed in writing by Lessee as set
forth on the vendor invoice of which a facsimile transmission will constitute an
original document. The Commencement Date for sale-leaseback Equipment shall be
the date Lessor tenders the purchase price. The Commencement Date for 800 Number
Equipment shall be fifteen (15) days from the ship date, such ship date to be
set forth on the vendor invoice or if unavailable on the vendor invoice the ship
date will be determined by Lessor upon other supporting shipping documentation.
Lessor will summarize all approved invoices, purchase documentation and evidence
of delivery, as applicable, received in the same calendar month into a Summary
Equipment Schedule in the form attached to this Schedule as Exhibit 1, and the
Initial Term will begin the first day of the calendar month thereafter. Each
Summary Equipment Schedule will contain the Equipment location, description,
serial number(s) and cost and will incorporate the terms and conditions of the
Master Lease and this Schedule and will constitute a separate lease.
<PAGE>

3.   Option to Extend

     So long as no Event of Default has occurred and is continuing hereunder,
and upon written notice no earlier than twelve (12) months and no later than
ninety (90) days prior to the expiration of the Initial Term of a Summary
Equipment Schedule, Lessee will have the right to extend the Initial Term of
such Summary Equipment Schedule for a period of one (1) year. In such event, the
rent to be paid during said extended period shall be mutually agreed upon and if
the parties cannot mutually agree within ninety (90) days of the expiration of
the Initial Term, then Lessee may revoke its election to extend the Initial Term
by notice given to Lessor within five (5) days thereafter. If such notice is not
given and an impasse is reached, then the Summary Equipment Schedule shall
continue in full force and effect pursuant to the existing terms and conditions
until terminated in accordance with its terms. The Summary Equipment Schedule
will continue in effect following said extended period until terminated by
either party upon not less than ninety (90) days prior written notice, which
notice shall be effective as of the date of receipt.

4.   Purchase Option

     So long as no Event of Default has occurred and is continuing hereunder,
and upon written notice no earlier than twelve (12) months and no later than
ninety (90) days prior to the expiration of the Initial Term or the extended
term of the applicable Summary Equipment Schedule, Lessee will have the option
at the expiration of the Initial Term or the extended term of the Summary
Equipment Schedule to purchase all, but not less than all, of the Equipment
listed therein for a purchase price not to exceed 15% of Lessor's cost hereunder
and upon terms and conditions to be mutually agreed upon by the parties
following Lessee's written notice, plus any taxes applicable at time of
purchase. Said purchase price shall be paid to Lessor on the expiration date of
the Initial Term or extended term. Title to the Equipment shall automatically
pass to Lessee upon payment in full of the purchase price but, in no event,
earlier than the expiration of the fixed Initial Term or extended term, if
applicable Notwithstanding the exercise by Lessee of this option and payment of
the purchase price, until all obligations under the applicable Summary Equipment
Schedule have been fulfilled, it is agreed and understood that Lessor shall
retain a purchase money security interest in the Equipment listed therein and
the Summary Equipment Schedule shall constitute a Security Agreement under the
Uniform Commercial Code of the state in which the Equipment is located.

If the parties are unable to agree on the purchase price or the terms and
conditions with respect to said purchase within ninety (90) days of the
expiration of the Initial Term or the renewal term, as applicable, then Lessee
may revoke its election to purchase the Equipment by notice given to Lessor
within five (5) days thereafter. If such notice is not given and an impasse is
reached, the Summary Equipment Schedule shall continue in full force and effect
pursuant to the existing terms and conditions until terminated by either party
upon not less than ninety (90) days prior written notice, which notice shall be
effective as of the date of receipt.

5.   Technology Exchange Option

     So long as no Event of Default has occurred and is continuing, and there is
no material adverse change in Lessee's credit, on or after the expiration of the
12th month of any Summary Equipment Schedule, Lessee shall have the option to
replace any of the Equipment subject to such summary Equipment Schedule with new
technology equipment ("New Technology Equipment") utilizing the following
guidelines:

A.   Equipment being replaced with New Technology Equipment shall have an
aggregate original cost equal to or greater than $20,000 and be comprised of
full configurations of equipment.

B.   This technology Exchange Option shall be limited to a maximum in the
aggregate of fifty percent (50%) of the original equipment cost and shall not
apply to software or any soft costs financed hereunder including but not limited
to tenant improvements and custom equipment.

C.   The cost of the New Technology Equipment must be equal to or greater than
the original equipment cost of the replaced equipment, but in no event shall
exceed 150% of the original equipment cost.

D.   The remaining lease payments applicable to the equipment being replaced by
the New Technology Equipment will be discounted to present value at 6%.

The wholesale market value of the equipment being replaced will be established
by Comdisco based upon then current market conditions. Upon the return of the
replaced equipment, the wholesale price will be deducted from the present value
of the remaining
<PAGE>

rentals and the differential will be added to the cost of the New Technology
Equipment in calculating the new rental. The lease for the New Technology
Equipment will contain terms and conditions substantially similar to those for
the replaced equipment and will have an Initial Term not less than the balance
of the remaining Initial Term for the replaced equipment.

8.   Special Terms

     The terms and conditions of the Lease as they pertain to this Schedule are
     hereby modified and amended as follows:

     (a)  Casualty Value Table is attached as Exhibit 2.

Master Lease: This Schedule is issued pursuant to the Lease identified on page 1
of this Schedule. All of the terms and conditions of the Lease are incorporated
in and made a part of this Schedule as if they were expressly set forth in this
Schedule. The parties hereby reaffirm all of the terms and conditions of the
Lease (including, without limitation, the representations and warranties set
forth in Section 8) except as modified herein by this Schedule. This Schedule
may not be amended or rescinded except by a writing signed by both parties.

     CHORUM TECHNOLOGIES, INC.                  COMDISCO, INC.
     as Lessee                                  as Lessor

     By: /s/ Kent Coker                         By:
        ---------------------------                ---------------------------

     Title:         CFO                         Title:
           ------------------------                   ------------------------

     Date:       3/2/00                         Date:
          -------------------------                  -------------------------
<PAGE>

                                   EXHIBIT 1

                          SUMMARY EQUIPMENT SCHEDULE
                          --------------------------

     This Summary Equipment Schedule dated XXXX is executed pursuant to
Equipment Schedule No. X to the Master Lease Agreement dated XXXX between
Comdisco, Inc. ("Lessor") and XXXX ("Lessee"). All of the terms, conditions,
representations and warranties of the Master Lease Agreement and Equipment
Schedule No. X are incorporated herein and made a part hereof, and this Summary
Equipment Schedule constitutes a Schedule for the Equipment on the attached
invoices.

1.   For Period Beginning:          And Ending:
     ---------------------          -----------

2.   Initial Term Starts on:        Initial Term:
     -----------------------        -------------
                                    (Number of Rent Intervals)

3.   Total Summary Equipment Cost:
     -----------------------------

4.   Lease Rate Factor:
     ------------------

5.   Rent:
     -----

6.   Acceptance Doc Type:
     --------------------
<PAGE>

                                   EXHIBIT 2
                                   ---------

                        CASUALTY VALUE TABLE - MONTHLY

The Casualty Value applicable to an item of Equipment will be the acquisition
cost multiplied by the Casualty Value Percentage set forth below applicable to
that item.
<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term     Initial Term      Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
DATE OF DELIVERY
TO INITIAL TERM
START DATE                          108.0000%          108.0000%          108.0000%         108.0000%      108.0000%

YEAR ONE

1st (Month of                       108.0000           108.0000           108.0000          108.0000       108.0000
2nd Initial Term)                   106.4157           106.7446           106.9550          107.1970       107.3658
3rd                                 104.8130           105.4746           105.8979          106.3846       106.7242
4th                                 103.1915           104.1898           104.8284          105.5628       106.0751
5th                                 101.5512           102.8899           103.7464          104.7314       105.4185
6th                                  99.8917           101.5749           102.6518          103.8902       104.7451
7th                                  98.2128           100.2446           101.5444          103.0393       104.0821
8th                                  96.5143            98.8988           100.4241          102.1784       103.4021
9th                                  94.7961            97.5372            99.2908          101.3075       102.7143
10th                                 93.0578            96.1598            98.1442          100.4265       102.0184
11th                                 91.2992            94.7662            96.9842           99.5351       101.3144
12th                                 89.5201            93.3565            95.8107           98.6334       100.6022

YEAR TWO

1 st (Month of                       87.7202            91.9303            94.6236           97.7211        99.8817
2nd Initial Term)                    85.8993            90.4874            93.4225           96.7982        99.1528
3rd                                  84.0572            89.0277            92.2075           95.8645        98.4154
4th                                  82.1936            87.5510            90.9783           94.9199        97.6694
5th                                  80.3083            86.0571            89.7347           93.9643        96.9147
6th                                  78.4009            84.5457            88.4766           92.9976        96.1511
7th                                  76.4713            83.0167            87.2039           92.0195        95.3787
8th                                  74.5192            81.4698            85.9163           91.0301        94.5972
9th                                  72.5444            79.9049            84.6137           90.0291        93.8067
10th                                 70.5464            78.3218            83.2958           89.0165        93.0069
11th                                 68.5252            76.7202            81.9627           87.9920        92.1978
12th                                 66.4804            75.0998            80.6139           86.9556        91.3792
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
YEAR THREE

1st (Month of                        64.4117           73.4606            79.2494           85.9071        90.5511
2nd Initial Term)                    62.3189           71.8023            77.8690           84.8463        89.7133
3rd                                  60.2017           70.1246            76.4725           83.7732        88.8658
4th                                  58.0598           68.4274            75.0597           82.6876        88.0083
5th                                  55.8929           66.7103            73.6305           81.5893        87.1409
6th                                  53.7007           64.9732            72.1845           80.4781        86.2633
7th                                  51.4830           63.2159            70.7217           79.3541        85.3755
8th                                  49.2393           61.4380            69.2418           78.2169        84.4774
9th                                  46.9695           59.6394            67.7447           77.0664        83.5687
10th                                 44.6732           57.8198            66.2300           75.9025        82.6495
11th                                 42.3502           55.9790            64.6977           74.7251        81.7196
12th                                 40.0000           54.1167            63.1476           73.5339        80.7787

YEAR FOUR

1st (Month of                        40.0000           52.2327            61.5793           72.3288        79.8270
2nd Initial Term)                    40.0000           50.3267            59.9928           71.1096        78.8641
3rd                                  40.0000           48.3985            58.3877           69.8762        77.8900
4th                                  40.0000           46.4478            56.7639           68.6284        76.9075
5th                                  40.0000           44.4743            55.1212           67.3661        75.9045
6th                                  40.0000           42.4778            53.4598           66.0891        74.8989
7th                                  40.0000           40.4580            51.7780           64.7971        73.8785
8th                                  40.0000           38.4146            50.0771           63.4901        72.8462
9th                                  40.0000           36.3474            48.3564           62.1678        71.8019
10th                                 40.0000           34.2561            46.6156           60.8301        70.7454
11th                                 40.0000           32.1404            44.8544           59.4768        69.6765
12th                                 40.0000           30.0000            43.0728           58.1077        68.5952

YEAR FIVE

1st (Month of                                          30.0000            41.2703           56.7226        67.5013
2nd Initial Term)                                      30.0000            39.4468           55.3214        66.3946
3rd                                                    30.0000            37.6021           53.9038        65.2750
4th                                                    30.0000            35.7358           52.4697        64.1423
5th                                                    30.0000            33.8477           51.0188        62.9965
6th                                                    30.0000            31.9376           49.5511        61.8372
7th                                                    30.0000            30.0053           48.0662        60.6645
8th                                                    30.0000            28.0504           46.5639        59.4780
9th                                                    30.0000            26.0726           45.0442        58.2777
10th                                                   30.0000            24.0719           43.5067        57.0634
11th                                                   30.0000            22.0477           41.9513        55.8350
12th                                                   30.0000            20.0000           40.3777        54.5922
</TABLE>
<PAGE>

<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
 YEAR SIX

 1st (Month of                                                            20.0000           38.7858        53.3349
 2nd Initial Term)                                                        20.0000           37.1753        52.0629
 3rd                                                                      20.0000           35.5460        50.7761
 4th                                                                      20.0000           33.8978        49.4743
 5th                                                                      20.0000           32.2302        48.1573
 6th                                                                      20.0000           30.5433        46.8249
 7th                                                                      20.0000           28.8366        45.4770
 8th                                                                      20.0000           27.1100        44.1134
 9th                                                                      20.0000           25.3633        42.7338
 10th                                                                     20.0000           23.5962        41.3382
 11th                                                                     20.0000           21.8085        39.9263
 12th                                                                     20.0000           20.0000        38.4979

YEAR SEVEN

1st (Month of                                                                               20.0000        37.0528
2nd Initial Term)                                                                           20.0000        35.5909
3rd                                                                                         20.0000        34.1119
4th                                                                                         20.0000        32.6157
5th                                                                                         20.0000        31.1020
6th                                                                                         20.0000        29.5707
7th                                                                                         20.0000        28.0214
8th                                                                                         20.0000        26.4542
9th                                                                                         20.0000        24.8686
10th                                                                                        20.0000        23.2645
11th                                                                                        20.0000        21.6417
12th                                                                                        20.0000       *20.0000
                                                                                            * Applicable Thereafter
</TABLE>
<PAGE>

                            EQUIPMENT SCHEDULE VL-6
                           DATED AS OF MARCH 1, 2000
                           TO MASTER LEASE AGREEMENT
              DATED AS OF SEPTEMBER 22, 1998 (THE "MASTER LEASE")

LESSEE: CHORUM TECHNOLOGIES, INC.               LESSOR: COMDISCO, INC.

Admin. Contact/Phone No.:                       Address for all Notices:
------------------------                        -----------------------
Mark Kightlinger                                6111 North River Road
Phone: 214-570-3530                             Rosemont, Illinois 60018
Fax: 214-570-3552                               Attn.: Venture Group
Address for Notices:
-------------------
1155 East Collins Blvd., Ste 200
Richardson, TX 75081

Central Billing Location:                       Rent Interval: Monthly
------------------------                        -------------
same as above

Attn.:

Lessee Reference No.: _____________
     (24 digits maximum)

Location of Equipment:                          Initial Term: 36 months
----------------------                          ------------
1) Same as above                                (Number of Rent Intervals)
2) 1303 East Arapaho
  Richardson, TX 75081
                                                Lease Rate Factor: 3.135%
                                                -----------------

Attn.:

EQUIPMENT (as defined below):                   Advance:       NONE
                                                -------

                                                Interim Rent:  NONE
                                                ------------

     Software, installation costs, maintenance fee, and tenant improvements
specifically approved by Lessor, which shall be delivered to and accepted by
Lessee during the period March 1, 2000 through September 1, 2001 ("Equipment
Delivery Period") for which Lessor receives vendor invoices approved for
payment, up to an aggregate purchase price of $1,600,000.00("Commitment
Amount'), excluding custom use equipment, delivery costs, rolling stock, special
tooling, hand held items, molds and fungible items.
<PAGE>

1.  Equipment Purchase

    This Schedule contemplates Lessor's acquisition of Equipment for lease to
Lessee, either by one of the first three categories listed below or by providing
Lessee with Equipment from the fourth category, in an aggregate value up to the
Commitment Amount referred to on the face of this Schedule. If the Equipment
acquired is of category (i), (ii) , (iii) below, the effectiveness of this
Schedule as it relates to those items of Equipment is contingent upon Lessee's
acknowledgment at the time Lessor acquires the Equipment that Lessee has either
received or approved the relevant purchase documentation between vendor and
Lessor for that Equipment.

     (i)     NEW ON-ORDER EQUIPMENT. Lessor will purchase new Equipment which is
             obtained from a vendor by Lessee for its use subject to Lessor's
             prior approval of the Equipment.

     (ii)    SALE-LEASEBACK EQUIPMENT. Any in-place Equipment installed at
             Lessee's site and to which Lessee has clear title and ownership may
             be considered by Lessor for inclusion under this Lease (the "Sale-
             Leaseback Transaction"). Any request for a Sale-Leaseback
             Transaction must be submitted to Lessor in writing (along with
             accompanying evidence of Lessee's Equipment ownership satisfactory
             to Lessor for all Equipment submitted) no later than April 1,
             2000*. Lessor will not perform a Sale-Leaseback Transaction for any
             request or accompanying Equipment ownership documents which arrive
             after the date marked above by an asterisk (*). Further, any sale-
             leaseback Equipment will be placed on lease subject to: (1) Lessor
             prior approval of the Equipment; and (2) if approved, at Lessor's
             actual net appraised Equipment value pursuant to the schedule
             below:

             ORIGINAL EQUIPMENT INVOICE   PERCENT OF ORIGINAL MANUFACTURER'S
                        DATE              NET EQUIPMENT COST PAID BY LESSOR
                        ----              ---------------------------------

             Between 12/03/99 - 04/01/00 (120 days)         100%

     (iii)   USED ON-ORDER EQUIPMENT. Lessor will purchase used Equipment which
             is obtained from a third party by Lessee for its use subject to
             Lessor's prior approval of the Equipment and at Lessor's appraised
             value for such used Equipment.

     (iv)    800 NUMBER EQUIPMENT. Upon Lessee's use of Comdisco's 1-800 Direct
             Service, Lessor will purchase new or used Equipment from a third
             party or Lessor will supply new or used Equipment from its
             inventory for use by Lessee at rates provided by Lessor.

2.   Commencement Date

     The Commencement Date for each item of new on-order or used on-order
Equipment will be the install date as confirmed in writing by Lessee as set
forth on the vendor invoice of which a facsimile transmission will constitute an
original document. The Commencement Date for sale-leaseback Equipment shall be
the date Lessor tenders the purchase price. The Commencement Date for 800 Number
Equipment shall be fifteen (15) days from the ship date, such ship date to be
set forth on the vendor invoice or if unavailable on the vendor invoice the ship
date will be determined by Lessor upon other supporting shipping documentation.
Lessor will summarize all approved invoices, purchase documentation and evidence
of delivery, as applicable, received in the same calendar month into a Summary
Equipment Schedule in the form attached to this Schedule as Exhibit 1, and the
Initial Term will begin the first day of the calendar month thereafter. Each
Summary Equipment Schedule will contain the Equipment location, description,
serial number(s) and cost and will incorporate the terms and conditions of the
Master Lease and this Schedule and will constitute a separate lease.

3.   Miscellaneous

     In consideration of Lessor financing software, installation costs,
maintenance fees, and tenant improvements hereunder, Lessee agrees in addition
to its last Monthly Rent Payment to remit to Lessor an amount equal to 12.5% of
Lessor's aggregate cost of software, installation costs, maintenance fees, and
tenant improvements provided hereunder.
<PAGE>

4.   Special Terms

     The terms and conditions of the Lease as they pertain to this Schedule are
     hereby modified and amended as follows:

          (a)  Section 9, Delivery and Return of Equipment
               -------------------------------------------

     Delete second, third and fourth sentences in their entirety.

          (b)  Casualty Value Table is attached as Exhibit

Master Lease: This Schedule is issued pursuant to the Lease identified on page 1
of this Schedule. All of the terms and conditions of the Lease are incorporated
in and made a part of this Schedule as if they were expressly set forth in this
Schedule. The parties hereby reaffirm all of the terms and conditions of the
Lease (including, without limitation, the representations and warranties set
forth in Section 8) except as modified herein by this Schedule. This Schedule
may not be amended or rescinded except by a writing signed by both parties.

     CHORUM TECHNOLOGIES, INC.                  COMDISCO, INC.
     as Lessee                                  as Lessor

     By:   /s/ Scott Grout                      By:
        ---------------------------                ---------------------------

     Title:                                     Title:
           ------------------------                   ------------------------

     Date:                                      Date:
          -------------------------                  -------------------------
<PAGE>

                                   EXHIBIT 1

                          SUMMARY EQUIPMENT SCHEDULE
                          --------------------------

     This Summary Equipment Schedule dated XXXX is executed pursuant to
Equipment Schedule No. X to the Master Lease Agreement dated XXXX between
Comdisco, Inc. ("Lessor") and XXXX ("Lessee"). All of the terms, conditions,
representations and warranties of the Master Lease Agreement and Equipment
Schedule No. X are incorporated herein and made a part hereof, and this Summary
Equipment Schedule constitutes a Schedule for the Equipment on the attached
invoices.

1.   For Period Beginning:          And Ending:
     ---------------------          -----------

2.   Initial Term Starts on:        Initial Term:
     -----------------------        -------------
                                    (Number of Rent Intervals)

3.   Total Summary Equipment Cost:
     -----------------------------

4.   Lease Rate Factor:
     ------------------

5.   Rent:
     -----

6.   Acceptance Doc Type:
     --------------------
<PAGE>

                                   EXHIBIT 2
                                   ---------

                        CASUALTY VALUE TABLE - MONTHLY

The Casualty Value applicable to an item of Equipment will be the acquisition
cost multiplied by the Casualty Value Percentage set forth below applicable to
that item.
<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
DATE OF DELIVERY
TO INITIAL TERM
START DATE                          108.0000%          108.0000%          108.0000%         108.0000%      108.0000%

YEAR ONE

1st (Month of                       108.0000           108.0000           108.0000          108.0000       108.0000
2nd Initial Term)                   106.4157           106.7446           106.9550          107.1970       107.3658
3rd                                 104.8130           105.4746           105.8979          106.3846       106.7242
4th                                 103.1915           104.1898           104.8284          105.5628       106.0751
5th                                 101.5512           102.8899           103.7464          104.7314       105.4185
6th                                  99.8917           101.5749           102.6518          103.8902       104.7451
7th                                  98.2128           100.2446           101.5444          103.0393       104.0821
8th                                  96.5143            98.8988           100.4241          102.1784       103.4021
9th                                  94.7961            97.5372            99.2908          101.3075       102.7143
10th                                 93.0578            96.1598            98.1442          100.4265       102.0184
11th                                 91.2992            94.7662            96.9842           99.5351       101.3144
12th                                 89.5201            93.3565            95.8107           98.6334       100.6022

YEAR TWO

1st (Month of                        87.7202            91.9303           94.6236           97.7211         99.8817
2nd Initial Term)                    85.8993            90.4874           93.4225           96.7982         99.1528
3rd                                  84.0572            89.0277           92.2075           95.8645         98.4154
4th                                  82.1936            87.5510           90.9783           94.9199         97.6694
5th                                  80.3083            86.0571           89.7347           93.9643         96.9147
6th                                  78.4009            84.5457           88.4766           92.9976         96.1511
7th                                  76.4713            83.0167           87.2039           92.0195         95.3787
8th                                  74.5192            81.4698           85.9163           91.0301         94.5972
9th                                  72.5444            79.9049           84.6137           90.0291         93.8067
10th                                 70.5464            78.3218           83.2958           89.0165         93.0069
11th                                 68.5252            76.7202           81.9627           87.9920         92.1978
12th                                 66.4804            75.0998           80.6139           86.9556         91.3792
</TABLE>
<PAGE>

<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
YEAR THREE

1st (Month of                        64.4117            73.4606           79.2494           85.9071         90.5511
2nd Initial Term)                    62.3189            71.8023           77.8690           84.8463         89.7133
3rd                                  60.2017            70.1246           76.4725           83.7732         88.8658
4th                                  58.0598            68.4274           75.0597           82.6876         88.0083
5th                                  55.8929            66.7103           73.6305           81.5893         87.1409
6th                                  53.7007            64.9732           72.1845           80.4781         86.2633
7th                                  51.4830            63.2159           70.7217           79.3541         85.3755
8th                                  49.2393            61.4380           69.2418           78.2169         84.4774
9th                                  46.9695            59.6394           67.7447           77.0664         83.5687
10th                                 44.6732            57.8198           66.2300           75.9025         82.6495
11th                                 42.3502            55.9790           64.6977           74.7251         81.7196
12th                                 40.0000            54.1167           63.1476           73.5339         80.7787

YEAR FOUR

1st (Month of                        40.0000            52.2327           61.5793           72.3288         79.8270
2nd Initial Term)                    40.0000            50.3267           59.9928           71.1096         78.8641
3rd                                  40.0000            48.3985           58.3877           69.8762         77.8900
4th                                  40.0000            46.4478           56.7639           68.6284         76.9075
5th                                  40.0000            44.4743           55.1212           67.3661         75.9045
6th                                  40.0000            42.4778           53.4598           66.0891         74.8989
7th                                  40.0000            40.4580           51.7780           64.7971         73.8785
8th                                  40.0000            38.4146           50.0771           63.4901         72.8462
9th                                  40.0000            36.3474           48.3564           62.1678         71.8019
10th                                 40.0000            34.2561           46.6156           60.8301         70.7454
11th                                 40.0000            32.1404           44.8544           59.4768         69.6765
12th                                 40.0000            30.0000           43.0728           58.1077         68.5952

YEAR FIVE

1st (Month of                                           30.0000           41.2703           56.7226         67.5013
2nd Initial Term)                                       30.0000           39.4468           55.3214         66.3946
3rd                                                     30.0000           37.6021           53.9038         65.2750
4th                                                     30.0000           35.7358           52.4697         64.1423
5th                                                     30.0000           33.8477           51.0188         62.9965
6th                                                     30.0000           31.9376           49.5511         61.8372
7th                                                     30.0000           30.0053           48.0662         60.6645
8th                                                     30.0000           28.0504           46.5639         59.4780
9th                                                     30.0000           26.0726           45.0442         58.2777
10th                                                    30.0000           24.0719           43.5067         57.0634
11th                                                    30.0000           22.0477           41.9513         55.8350
12th                                                    30.0000           20.0000           40.3777         54.5922
</TABLE>
<PAGE>

<TABLE>
<CAPTION>

                               ------------------------------------------------------------------------------------------
                                                                                                      83 Months
                                1-47 Months     48-59 Months       60-71 Months      72-83 Months     and beyond
                                Initial Term    Initial Term       Initial Term      Initial Term     Initial Term
                               ------------------------------------------------------------------------------------------
<S>                            <C>            <C>                <C>                <C>               <C>
 YEAR SIX

 1st (Month of                                                            20.0000           38.7858         53.3349
 2nd Initial Term)                                                        20.0000           37.1753         52.0629
 3rd                                                                      20.0000           35.5460         50.7761
 4th                                                                      20.0000           33.8978         49.4743
 5th                                                                      20.0000           32.2302         48.1573
 6th                                                                      20.0000           30.5433         46.8249
 7th                                                                      20.0000           28.8366         45.4770
 8th                                                                      20.0000           27.1100         44.1134
 9th                                                                      20.0000           25.3633         42.7338
 10th                                                                     20.0000           23.5962         41.3382
 11th                                                                     20.0000           21.8085         39.9263
 12th                                                                     20.0000           20.0000         38.4979

 YEAR SEVEN

1st (Month of                                                                               20.0000         37.0528
2nd Initial Term)                                                                           20.0000         35.5909
3rd                                                                                         20.0000         34.1119
4th                                                                                         20.0000         32.6157
5th                                                                                         20.0000         31.1020
6th                                                                                         20.0000         29.5707
7th                                                                                         20.0000         28.0214
8th                                                                                         20.0000         26.4542
9th                                                                                         20.0000         24.8686
10th                                                                                        20.0000         23.2645
11th                                                                                        20.0000         21.6417
12th                                                                                        20.0000        *20.0000
                                                                                            * Applicable Thereafter
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
                                                             EXHIBIT B

                  CHORUM TECHNOLOGIES INC.
                  Schedule of Fixed Assets
Item     Purchase
#        Date Vendor                                 Description                         Invoice #                    Asset
                                                                                                            Serial No. Tag #
------------------------------------------------------------------------------------------------------------------------------------
<S>     <C>                              <C>                                            <C>         <C>
  171   8114/98 Grainger                 60" w Electronic Riser                         1929521746                    N/A
  172   8/14/98 Grainger                 Chrome wire shelving                           3547812101                    NIA
  173   8/10/98 EZConn Enterprise Inc.   Fusion Splicer                                     870810  s-174
  174   8/10/98 EZConn Enterprise Inc.   High Precision Cleaver & fiber Stripper            870810                S321 8 S210
  175   8/26/98 Rifocs Fiber Optic       Loss Analyzer Set                       1021197 in  11003, 110995 R 110970, 110982 8 111020
  175a  8/26/98 Rifocs Fiber Optic       (parts have s/n's)                      1021197-in  111021 8 110440, 110441, 110613 ,110614
  176   8/31/98 Ando Corporation         Optical Spectrum analyzer                           98194                   80684507
  177   8/24/98 Newport                  Rotary Stage. 46MM                                  631658
  178   8124/98 Newport                  Bracket, universal                                  631658
  179   9/9/98 Hewlett Packard           Tunable Laser Source 8 connector                   7bg2625                 3611800306
  180   8/24/98 Rifocs Fiber Optic       Visual Fault Finder - Laser Source Pen, 635n       9838323
  181    8/31/98 Techni-Tool              Two Port Soldering System                          794448
</TABLE>

<TABLE>
<CAPTION>
                                                                      Financed     Unit    Subtotal    Frieght Tax   Acquisition
                                                           Quantity    Amount      Price              Installation      Price
--------------------------------------------------------------------------------------------------------------------------------
<S>                                                        <C>       <C>        <C>        <C>        <C>           <C>
  171   8114/98 Grainger                                         1      52.83      52.83      52.83          4.36        57.19
  172   8/14/98 Grainger                                         1     208.13     208.13     208.13         17.17       225.30
  173   8/10/98 EZConn Enterprise Inc.                           1   18500.00   18500.00   18500.00          0.00     18500.00
  174   8/10/98 EZConn Enterprise Inc.                           1    1200.00               1200.00          0.00      1200.00
  175   8/26/98 Rifocs Fiber Optic                               2   14612.00    7306.00   14612.00         32.24     14644.24
  175a  8/26/98 Rifocs Fiber Optic                                                                        3128.79     39628.79
  176   8/31/98 Ando Corporation                                 1   36500.00   36500.00   36500.00          0.00      2288.00
  177   8/24/98 Newport                                          4    2288.00     572.00    2288.00         18.40       168.40
  178   8124/98 Newport                                          2     150.00      75.00     150.00       4234.06     55556.06
  179   9/9/98 Hewlett Packard                                   1   51322.00   51322.00   51322.00          4.01      1789.01
  180   8/24/98 Rifocs Fiber Optic                               3    1785.00     595.00    1785.00        238.91      1605.61
  181    8/31/98 Techni-Tool                                     2    1366.70     683.35    1366.70        238.91       238.91
                TOTAL HDWE/COMPUTER/EQUIP                           740980.10  606804.78  740980.10      45340.94    786321.04
</TABLE>

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00016-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00016-of-00352.parquet"}]]