<PAGE>

                                                            EXHIBIT 10.3

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.



                        PURCHASE AND LICENSE AGREEMENT

                                    BETWEEN

                            SYCAMORE NETWORKS, INC.

                                      AND

                         WILLIAMS COMMUNICATIONS, INC.



Exhibit(s):

Exhibit A:  Additional Terms and Conditions
Exhibit B:  Discount Schedule
Exhibit C:  Insurance Terms
Exhibit D:  Year 2000 Statement
Exhibit E:  Escrow Agreement
Exhibit F:  Maintenance

                  CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                  -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            -----------------------
<PAGE>

                        PURCHASE AND LICENSE AGREEMENT
                        ------------------------------


THIS AGREEMENT is made effective as of the date written below by and between
Sycamore Networks, Inc. ("Sycamore"), a Delaware corporation having a principal
place of business at 2 Highwood Drive, Suite 202 Tewksbury, MA 01876, and
Williams Communications, Inc. ("Williams") a Delaware corporation having a
principal place of business at One Williams Center, Tulsa, OK  74172.

Recitals of Fact

1.   Sycamore sells and licenses various hardware and software products (the
     "Products").

2.   Williams desires to purchase and license Products from Sycamore during the
     term of this Agreement for its internal use only.

NOW, THEREFORE, in consideration of their mutual promises and obligations
contained in this Agreement, the parties agree as follows:

1.   Term
     ----

     This Agreement shall become effective as of the date written below and
     shall continue for a period of three (3) years, after which it shall renew
     automatically for successive twelve (12) month additional terms, unless
     otherwise terminated pursuant to the terms hereof.

2.   Purchase
     --------

2.1  During the term of this Agreement, and upon the terms and conditions set
     forth herein, Sycamore shall sell to Affiliates Communications, Inc., and
     to its parent Company and any parents of its parent Company as well as any
     of the parents majority owned subsidiaries (hereinafter Affiliates), and
     Williams and its Affiliates may from time to time purchase from Sycamore
     Products at pricing listed in Sycamore's then-current price list applicable
     to each such Product, as amended from time to time, less any applicable
     discounts. Any Williams' Affiliate may order Products under this Agreement
     so long as such an order references this Agreement and includes a statement
     whereby the ordering entity agrees to be bound by the terms and conditions
     contained herein. The parties hereby agree that additional terms and
     conditions of the Williams purchase of Sycamore's Transponder Product shall
     be those set forth in Exhibit A.

2.2  Shipments of the Products shall be made only against written purchase
     orders issued by Williams. At a minimum, each purchase order shall specify
     the following items:

     a.   A complete list of the Products covered by the purchase order,
          specifying the quantity, model number and description of each;

     b.   The price of each Product as set forth on the attached price list and
          subject to the terms of Section 6, below, and any applicable
          discounts, and any additional charges and costs;


                                       2
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
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                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

     c.   The billing address, the destination to which the Products will be
          delivered, and the requested delivery date; and

     d.   The signature of Williams employee or agent who possesses the
          authority to place such an order.

     Sycamore shall not be obligated to accept any order in which Williams fails
     to include the items in a through d, above. However if such order is
     accepted, such failure shall not cause Williams not to receive the
     applicable discount for such order.

2.3  Sycamore shall acknowledge Williams purchase orders in writing within five
     (5) days after receipt. Sycamore's acknowledgment shall note any exceptions
     regarding matters such as the items ordered, configuration, and Product
     pricing.  Sycamore shall also confirm the requested delivery date or offer
     an alternative delivery date.  In no event shall any order be binding on
     Sycamore's until Williams order and Sycamore's acknowledgment are in
     agreement as to the items ordered, configuration, pricing, delivery dates,
     and all other material terms.

2.4  No purchase order, acknowledgment form, or other ordering document or
     communication from either party shall vary the terms and conditions on this
     Agreement unless both parties expressly agree in writing.  In the event of
     any conflict between the terms and conditions of this Agreement and those
     of any purchase order acknowledgment form or other ordering document or
     communication, the terms and conditions of this Agreement shall prevail.

3.   Delivery
     --------

3.1  All deliveries of the Products purchased pursuant to this Agreement will be
     made FOB Sycamore's facility. All Products will be packaged for shipment in
     accordance with standard industry practices.  All transportation, shipping,
     and insurance costs up to the delivery point at Williams' premises shall be
     arranged by Sycamore in accordance with Williams' instructions and shall be
     charged to Williams' account. If Williams does not notify Sycamore of a
     preferred freight forwarder, Sycamore shall select a freight forwarder to
     be used for shipment of the Products to Williams. Risk of loss shall pass
     to Williams at the point of delivery at Williams' premises. In addition,
     replacement product for Product damaged in transit shall be provided by
     Sycamore on a non-discriminatory first priority basis.

3.2  Title (excluding  title to software Products) shall pass to Williams at
     the point of delivery to the common carrier at Sycamore's facility.

3.3  Sycamore shall use reasonable efforts to ship the Products on the shipment
     date requested in Williams' purchase order.  Sycamore shall not be liable
     for any loss, expense or damage incurred by Williams if Sycamore fails to
     meet the specified delivery date. Sycamore reserves the right to allocate
     shipment of Products among its purchasers and to make partial shipments.
     Notwithstanding the foregoing, partial shipments shall only be made with
     previous written

                                       3
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

Confidential Material omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

     approval by Williams. If shipment is delayed more than [**] days from the
     mutually agreed upon shipment date due to Sycamore's delay only, Williams
     may cancel an order upon prior written notice to Sycamore. For the purposes
     of computing Williams discount level only, shipments cancelled pursuant to
     the previous sentence of this sub-paragraph 3.3, shall be deemed to have
     shipped.

3.4  All shipments with destinations outside of the US shall be subject to
     Sycamore's determination that such shipments are in compliance with all
     applicable export and import regulations. For shipment other than in the
     US, Williams will be solely responsible for (i) obtaining any license that
     may be required to import the Products into its country (ii) clearing the
     Products through local customs upon their arrival to Williams country and
     (iii) paying all customs duties, taxes and other charges assessed on such
     importation's in such country.  In no event shall Sycamore delay in
     shipping or refusal to ship due to export or import issues be deemed a
     default hereunder.

4.   Rescheduling and Cancellation of Orders
     ---------------------------------------

4.1  Upon written notice to Sycamore provided at least [**] days' prior to the
     scheduled ship date, Williams may reschedule the delivery of any Products
     scheduled for shipment by up to [**] days at no charge.  Orders may,
     however, be rescheduled only once, except that on an emergency basis,
     Williams may reschedule more than once so long as any subsequent
     rescheduled shipping date is not more than [**] days form the original
     scheduled shipment date.  Acceptance of Williams' request to reschedule any
     delivery with less than [**] days' prior written notice to Sycamore shall
     be at the sole discretion of Sycamore.

4.2  Upon at least  [**] days' written notice to Sycamore prior to the
     originally-scheduled shipment date of Products under this Agreement,
     Williams may cancel any shipment of the Products without charge.  The
     following cancellation charges apply to any cancellations made by Williams
     less than [**] days prior to shipment as liquidated damages and not as a
     penalty based on the number of days prior to the scheduled delivery that
     written notice of cancellation is received by Sycamore:

               Days Notice                    Charge
               -----------                    ------
                                    (% of canceled order)

               Greater than  [**] days        [**]%
               [**] days                      [**]%
               [**] days                      [**]%




                                       4
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

Confidential Material omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.


5.   Prices
     ------

5.1  During the term of this Agreement, Williams shall be entitled to purchase
     the Products at the prices set forth in Sycamore then-current Price List,
     an example of which is attached hereto, applicable to each particular
     Product, less any applicable discounts based on annual purchase volume
     listed in Exhibit B.  All prices set forth in Sycamore Price List are
               ---------
     exclusive of any applicable value added, excise, sales, use or consumption
     taxes, customs duties or other governmental charges except for any taxes
     imposed upon the income of Sycamore or upon its employment base.

5.2  (a)  In the event of a Sycamore price increase, all Products ordered on or
     after the effective date of such price increase shall be filled at the new
     higher price.  Sycamore will provide Williams with written notice of any
     price increase [**] days prior to the effective date of such price
     increase.  Sycamore shall, however, honor all written and accepted Williams
     purchase orders for the Products received by Sycamore prior to the price
     increase effective date at the prices in effect as of the date the order
     was received, but only if Williams requests Sycamore to ship the Products
     within [**] days after the effective date of the price increase.

     (b) In the event of an Sycamore price decrease, all products ordered on or
     after the effective date of such price decrease shall be filled at the new
     lower price.

6.   Payment
     -------

6.1  Sycamore shall invoice Williams upon shipment of the Products.  Williams
     shall pay all invoices in US dollars within [**] days of receipt.  All such
     invoices will be payable by check or wire transfer, to the following
     accounts, in United States dollars:

     For Wire Transfers:

     -------------------------------------------------------


     -------------------------------------------------------


     In the event that Williams fails to make any payment when due, Sycamore may
     withhold further shipments until such time as the past-due payment is made,
     and may require that subsequent orders be paid in full prior to shipment

6.2  Sycamore reserves the right to impose a late payment charge of one and one-
     half percent (1 1/2%) per month, or the maximum allowed by law, whichever
     is less for each month that any payment is late, including the month in
     which the payment was due and not paid.




                                       5
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

Confidential Material omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

6.3  Williams shall pay all municipal, state, county or federal taxes including,
     but not limited to, sales, use, excise, value added or other taxes which
     may be levied upon the sale, license or transfer, ownership or installation
     of the Products except for any taxes imposed upon the income of Sycamore or
     upon its employment base.

7.   Changes / Availability of Products
     ----------------------------------

7.1  Sycamore shall promptly inform Williams as soon as is reasonably
     practicable after Sycamore schedules discontinuance of production or
     modification of any hardware Product.  Sycamore, in its sole discretion,
     may modify its price list at any time.  Sycamore agrees to offer services
     for any discontinued product for a period of [**] from the last date of
     shipment of the discontinued product.  Sycamore also agrees to offer a one-
     time buy-out of spare parts for any discontinued product for a period of
     [**] days following the announcement of any discontinuance.

7.2  At any time prior to delivery, Sycamore may make changes in the Products in
     whole or in part to be supplied to the Williams hereunder to include
     electrical or mechanical design refinements that Sycamore deems
     appropriate, or as required by law or concerns of safety, without
     obligation to modify or change any Product previously delivered or to
     supply Products in accordance with earlier specifications.

8.   License of Software Products and Firmware
     -----------------------------------------

8.1  Subject to the provisions of this Section, Sycamore grants to Williams a
     nonexclusive, nontransferable, (except for transfers in accordance with the
     terms herein and in conjunction with the transfer of the Products with
     which the software is first delivered), license to use the object code form
     of the software Products solely for Williams' internal business purposes
     (including, without limitation, in conjunction with Williams' provision of
     services to its customers) on or in conjunction with the Product with which
     it was originally delivered.

8.2  Subject only to the licenses specifically granted herein, Sycamore is the
     sole owner of all rights, title and interest, including all copyrights,
     patents, trademarks, industrial designs, trade names, trade secrets and
     other intellectual property rights in the software Products.  The software
     Products are copyrighted and Williams is only authorized to reproduce one
     copy of the software Products solely for back-up purposes.  Williams is
     hereby prohibited from otherwise copying or translating, modifying or
     adapting the software Products or, incorporating in whole or any part in
     any other product or creating derivative works based on all or any part of
     the Products.  Williams is not authorized to license others to reproduce
     any copies of the software Products, except as expressly provided in this
     Agreement.  Williams agrees to ensure that all copyright, trademark and
     other proprietary notices of Sycamore affixed to or displayed on the
     software Products will not be removed or modified.  Williams shall not
     decompile, disassemble or reverse engineer, the software Products or any
     component thereof, except as may be permitted by applicable law in which
     case Williams must notify Sycamore in writing and Sycamore may provide
     review and assistance.



                                       6
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

Confidential Material omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

8.3  The rights and licenses granted to Williams with respect to any software
     Product furnished by Sycamore may not be sold, licensed, sublicensed,
     rented, assigned or otherwise transferred to another party without the
     prior written consent of Sycamore except Williams may assign to an entity
     controlling, controlled by or under common control of Williams or pursuant
     to Section 8.6. Williams shall provide written notice of such assignment
     within a reasonable time thereafter.

8.4  Upon the effective date of a termination of this Agreement by Sycamore for
     Williams breach, the license granted to Williams under this Agreement shall
     terminate and Williams shall immediately discontinue use of the software
     and all copies and documentation thereof and return all copies and
     documentation to Sycamore. A termination of this Agreement by Williams for
     Sycamore's breach shall not terminate Williams' license hereunder.

8.5  US Government Restricted Rights. Notice - Distribution and use of products
     including computer programs and any related documentation and derivative
     works thereof, to and by the United States Government, are subject to the
     Restricted Rights provisions of FAR 52.227-19, paragraph (c)(2) as
     applicable, except for purchases by agencies of the Department of Defense
     (DOD).   If the Software is acquired under the terms of a Department of
     Defense or civilian agency contract, the Software is "commercial item" as
     that term is defined at 48 C.F.R. 2.101 (Oct. 1995), consisting of
     "commercial computer software" and "commercial computer software
     documentation" as such terms are used in 48 C.F.R. 12.212 of the Federal
     Acquisition Regulations and its successors and 48 C.F.R. 227.7202-1 through
     227.7202-4 (June 1995) of the DoD FAR Supplement and its successors.  All
     U.S. Government end users acquire the Software with only those rights set
     forth in this Agreement.   Manufacturer is Sycamore Networks, 2 Highwood
     Drive, Suite 202, Tewksbury, MA 01876.  Unpublished - rights reserved under
     the copyright laws of the United States.

8.6  Williams may transfer the rights to use the software in conjunction with
     the Products on which the software is first supplied, by means of an
     enforceable sub-license having terms with regard to Williams' sub-
     licensee's use which are no less restrictive than those as set forth in
     this paragraph 8, except that any such sub-licensee may not subsequently
     transfer such sub-license rights without Sycamore's written assent.

9.   Support
     -------

     Williams may elect to purchase maintenance or support services from
     Sycamore in connection with the Products pursuant to Sycamore's standard
     terms and conditions and then-current programs.  The provision of all such
     maintenance and support services shall be governed by the applicable
     agreement entered into between the parties.  (See Exhibit F for Maintenance
     options)

10.  Limited Warranty
     ----------------

10.1 Product Warranty:  Product hardware and media are warranted to be free from
     defects in material and workmanship during the Warranty Period (as defined
     below). Product hardware and software is warranted to conform substantially
     to Sycamore's then current (as of the date of Sycamore's product shipment)
     published user documentation during the Warranty Period. The Warranty
     Period is [**] for Product hardware, Product software, and media. Product
     support beyond these periods may be available at additional cost under a
     Maintenance Service Agreement. The warranty shall commence upon delivery.


                                       7
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------


<PAGE>

10.2  Warranty Claims: Sycamore shall incur no liability under this warranty if
      the end user fails to provide Sycamore with notice of the alleged defect
      during the applicable Warranty Period. After receiving such notice,
      Sycamore's Technical Assistance Center ("TAC") will notify the purchaser
      of its designation of one of the following problem resolution methods:

          Return to Factory:  The allegedly defective goods must be returned to
          Sycamore within ten days of receipt of the replacement product and in
          accordance with Sycamore's Return to Factory repair procedures.

          Other:  TAC will use best efforts to deliver non-priority services to
          repair, correct or workaround the problem by means of telephone
          support, including patches, corrective software releases or other
          means reasonably determined by Sycamore.

      Sycamore shall incur no liability under this warranty if Sycamore's tests
      disclose that the alleged defect is due to causes not within Sycamore's
      reasonable control, including alteration or abuse of the goods. Under the
      Return to Factory alternative, if a Product is determined not to be
      defective or to have a defect due to causes not within Sycamore's
      reasonable control, Sycamore's then current repair price as listed in the
      price list will apply.

10.3  Sycamore warrants and represents that the Products shall record, store,
      process, and present calendar dates falling on or after January 1, 2000,
      in the same manner, and with the same functionality, as such Products
      record, store, process and present calendar dates falling on or before
      December 31, 1999. Sycamore further warrants that in all other respects
      such Products shall not lose functionality or degrade in performance as a
      consequence of such Products operating in a date later than December 31,
      1999. Sycamore shall also consult with Williams to (i) ensure that such
      Products will lose no functionality with respect to the introduction of
      records containing dates falling on or after January 1, 2000, and (ii)
      under terms and prices mutually agreed upon, to use commercially
      reasonable efforts to ensure that such Products will be interoperable with
      other software used by Williams which will interact directly with the
      Sycamore Products in the course of processing data. Notwithstanding the
      foregoing, Sycamore shall have no responsibility to the extent any loss of
      functionality or degradation or failure to record, store, process or
      present calendar dates falling on or after January 1, 2000 is caused by
      the failure to so perform of any software of systems other than Sycamore's
      used by Williams or any other supplier of Williams. Sycamore will perform
      the above warranty obligations at no charge to Williams.

10.4. Sycamore warrants, except as stated in Sycamore's published
      specifications, or as otherwise agreed, that any software provided to
      Williams by Sycamore shall, to Sycamore's knowledge as of the date of this
      Agreement: (a) contain no hidden files; (b) not replicate, transmit, or
      activate itself without control of a person operating computing equipment
      on which it resides; (c) not alter, damage, or erase any data or computer
      programs without control of a person operating the computing equipment on
      which it resides; (d) contain no encrypted imbedded key unknown to




                                       8
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks donate omissions.

      Williams, node lock, timeout or other function, whether implemented by
      electronic, mechanical or other means, which restricts or may restrict use
      of access to any programs or data developed under this Agreement, based on
      residency on a specific hardware configuration, frequency of duration of
      use, or other limiting criteria.

10.5 Sycamore's Liability:  Sycamore's liability for breach of warranty
     hereunder, and end user's sole and exclusive remedy, shall be limited to
     the express remedies set forth in this Sycamore's Product Warranty.

10.6 Disclaimer of Warranties:  SYCAMORE MAKES NO OTHER WARRANTIES, EXPRESS,
     IMPLIED OR STATUTORY, REGARDING PRODUCTS. ALL OTHER WARRANTIES AS TO THE
     QUALITY, CONDITION, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
     NONINFRINGEMENT ARE EXPRESSLY DISCLAIMED.

10.7 Limitation of Liability:  NEITHER PARTY SHALL BE RESPONSIBLE FOR ANY
     SPECIAL, CONSEQUENTIAL, INCIDENTAL, OR PUNITIVE DAMAGE, INCLUDING, BUT NOT
     LIMITED TO, LOSS OF PROFITS OR DAMAGES TO BUSINESS OR BUSINESS RELATIONS,
     WHETHER OR NOT ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES THE
     FOREGOING LIMITATIONS SHALL APPLY NOTWITHSTANDING THE FAILURE OF ANY
     EXCLUSIVE REMEDIES.

10.8 Warranty Repair (Return to Factory):  If TAC designates Return to Factory
     as the appropriate problem resolution method, the following provisions
     apply.

     (a)  During the first [**] days of the warranty period, Sycamore may at its
     option provide an advance replacement of a defective Product.  Sycamore
     will repair or replace defective Product hardware covered under warranty
     within[**] business days of receipt of the Product. The warranty period for
     the replaced product shall be [**] days or the remainder of the warranty
     period of the original unit, whichever is greater.  Sycamore will ship
     surface freight. Expedited freight is at end user's expense.

     (b)  The end user must return the defective Product to Sycamore within [**]
     days of receipt of the replacement product. If the defective Product is not
     returned within this time period, Sycamore will bill the end user for the
     Product at list price, less Williams' discount, if applicable.

10.9 Out-of-Warranty Repair (Hardware): Sycamore will either repair or, at its
     option, replace defective Product hardware not covered under warranty
     within [**] working days of its receipt. Repair charges are available from
     the Repair Facility upon request. The warranty on a serviced Product is
     [**] days from date of shipment of the serviced unit.  Out-of-warranty
     repair charges are based upon the prices in effect at the time of return.

10.10  In the event that Sycamore, given full cooperation by Williams, is
     unable, after repeated efforts over a period of no less than [**] days, to
     correct significant and material non-conformances of



                                       9
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

     the Products to the specification in effect as of the sale of the Product,
     Sycamore agrees that after good faith negotiations to resolve the matter,
     Williams may elect to deem such circumstance a failure of Sycamore's
     obligation of tender of delivery of conforming Product and Williams may
     revoke its purchase.

11.  Intellectual Property Rights
     ----------------------------

     Except as described in this Agreement, Sycamore does not grant and Williams
     acknowledges that it shall have no right, license or interest in any of the
     patents, copyrights, trademarks, or trade secrets owned, used or claimed
     now by Sycamore.  All applicable rights to such patents, copyrights,
     trademarks, and trade secrets are and will remain the exclusive property of
     Sycamore Subject to the rights expressly granted to Williams by this
     Agreement,  title to and ownership of the intellectual property rights
     contained in the Products or any part of the Products or Sycamore's
     confidential information shall remain Sycamore's property.


12.  Patent and Copyright Indemnification
     ------------------------------------

12.1 Sycamore agrees to indemnify and hold Williams harmless from and against
     all claims and judicial or governmental determinations that the Products as
     delivered by Sycamore under this Agreement infringe or misappropriate any
     United States patent rights, copyrights, trade secrets, or trademarks.
     Sycamore shall assume the defense of any such claim regardless as to its
     ultimate validity, of infringement or misappropriation brought against
     Williams in the United States by counsel retained at Sycamore's own
     expense, provided that Williams promptly notifies Sycamore in writing of
     such claim or the commencement of any such suit, action, proceeding or
     threat covered by this Section.  Sycamore shall maintain sole and exclusive
     control of the defense and/or settlement of any such claim and Williams
     shall cooperate in the defense of such claim.

12.2 In the event that the use or sale of all or any portion of the Products is
     enjoined, or, in Sycamore's judgment, may be enjoined, as a result of a
     suit based on alleged infringement or misappropriation of the third party
     intellectual property rights, Sycamore agrees to either: (i) procure for
     Williams the right to continue to use the Product, or (ii) replace or
     modify the infringing or misappropriating Product so that it becomes non-
     infringing.  In the event that the foregoing alternatives cannot be
     reasonably accomplished by Sycamore, Sycamore shall direct Williams to
     return the Product to Sycamore and upon receipt of the Product(s), Sycamore
     shall reimburse Williams for the price originally paid by Williams.  Upon
     Sycamore's fulfillment of the alternatives set out in this Section and
     Section 12.1, Sycamore shall be relieved of any further obligation or
     liability to Williams as a result of any such infringement or
     misappropriation.

12.3 Regardless of any other provisions of this Agreement, this Section shall
     not apply (i) to any designs, specifications or modifications originating
     with or requested by Williams, or (ii) to the combination of any Product
     with other equipment, software or products not supplied by Sycamore if such
     infringement or misappropriation would not have occurred but for such
     combination, or (iii) Williams failure to install an update provided at no
     additional charge, where the update would have avoided the infringement
     claim.



                                      10
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

12.4 THIS SECTION 12 STATES SYCAMORE'S ENTIRE LIABILITY TO WILLIAMS AND
     WILLIAMS' SOLE REMEDY FOR ANY INFRINGEMENT OR MISAPPROPRIATION OF ANY
     PATENT RIGHTS, COPYRIGHTS, TRADE SECRETS, TRADEMARKS OR OTHER INTELLECTUAL
     PROPERTY RIGHTS.

13.  General Indemnity
     -----------------

     Each party agrees to indemnify and hold harmless the other party (including
     their directors, officers, employees, agents, representatives, affiliates,
     and subcontractors) from and against any claims, damages and liabilities,
     including reasonable attorney's fees, asserted by any person or entity due
     to personal injury (including death) or tangible property damage to the
     extent resulting from any negligent act or omission of such party;
     provided, however, that such party shall not be liable for that portion of
     liabilities which are caused by the sole negligence of  the other party.

14.  Limitation of Liability
     -----------------------

     IN NO EVENT SHALL EITHER PARTY BE LIABLE FOR INDIRECT, INCIDENTAL, SPECIAL,
     CONSEQUENTIAL, EXEMPLARY PUNITIVE DAMAGES OR LOST PROFITS, WHETHER
     FORESEEABLE OR UNFORESEEABLE, OF ANY KIND WHATSOEVER (INCLUDING, WITHOUT
     LIMITATION, LOST PROFITS, LOSS OF GOODWILL, LOSS OR DAMAGED DATA OR
     SOFTWARE (EXCEPT IN THE CASE OF SOFTWARE, AS STATED IN SYCAMORE'S WARRANTY
     FOR SOFTWARE), LOSS OF USE OF THE PRODUCTS, DOWNTIME OR COSTS OF SUBSTITUTE
     PRODUCTS OR EQUIPMENT) ARISING FROM THE SALE AND DELIVERY OF THE PRODUCTS
     OR ANY OTHER ACT OF EITHER PARTY IN CONNECTION WITH THIS AGREEMENT, EVEN IF
     SUCH PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.  NO
     LIMITATION AS TO DAMAGES FOR PERSONAL INJURY (INCLUDING DEATH) OR TANGIBLE
     PROPERTY DAMAGE IS HEREBY INTENDED.  SOME STATES DO NOT ALLOW THE EXCLUSION
     OR LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES AND THE ABOVE
     EXCLUSION OR LIMITATION MAY NOT APPLY.

15.  Confidentiality
     ---------------

15.1 For purposes of this Agreement, "Confidential Information" shall mean all
     information (i) identified in written or oral format by the disclosing
     party as confidential, trade secret or proprietary information and, if
     disclosed orally, summarized in written format within ten (10) days of
     disclosure.

15.2 Notwithstanding the foregoing, "Confidential Information" shall not include
                                                                     ---
     any information which the receiving party can show: (a) is now or
     subsequently becomes legally and publicly available without breach of this
     Agreement by the receiving party, (b) was rightfully in the possession of
     the receiving party without any obligation of confidentiality prior to
     receiving it from the


                                      11
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                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

     disclosing party, (c) was rightfully obtained by the
     receiving party from a source other than the disclosing party without any
     obligation of confidentiality, (d) was developed by or for the receiving
     party independently and without reference to any Confidential Information
     and such independent development can be shown by documentary evidence, or
     (e) is disclosed pursuant to an order of a court or governmental agency as
     so required by such order, provided that the receiving party shall first
     notify the disclosing party of such order and afford the disclosing party
     the opportunity to seek a protective order relating to such disclosure.

15.3 Both Parties agree not to use such Confidential Information except in their
     performance under this Agreement.  In addition, both parties shall treat
     and protect such information in the same manner as it treats its own
     information of like character, but with not less than reasonable care.
     Both parties agree to take appropriate measures by instruction and written
     agreement prior to disclosure of Confidential Information to their
     employees to prevent unauthorized use or disclosure.  The obligations of
     this Section with regard to Confidential Information shall continue for a
     period of three (3) years after termination or expiration of this
     Agreement, except that the period with respect to any Confidential
     Information identified as a trade secret shall be perpetual. Confidential
     Information must be returned by the receiving party upon termination or
     expiration of this Agreement.

15.4 In the event of a breach of any of the foregoing provisions, both parties
     agree that the harm suffered by the disclosing party would not be
     compensable by monetary damages alone and, accordingly, that the disclosing
     party shall, in addition to other available legal or equitable remedies, be
     entitled to an injunction against such breach.

16.  Termination
     -----------

16.1 Either party may terminate this Agreement at any time, with or without
     cause, upon ninety (90) days prior written notice to the other party.

16.2 If Williams is in breach of this Agreement, Sycamore shall give Williams
     thirty (30) days' prior written notice to cure such breach.  If such breach
     has not been cured to Sycamore's satisfaction within such thirty (30) day
     period, then this Agreement shall automatically terminate at the end of
     said thirty (30) day period without further notice to Williams.   If
     Williams is in breach of the Section entitled License of Software Products
     and Firmware, and fails to cure such breach within five (5) days of notice,
     Sycamore shall have the right to immediately terminate this Agreement.

16.3 This Agreement may be terminated for cause by either party in the event
     that the other party: (i) shall become insolvent; (ii) commits an act of
     bankruptcy; (iii) seeks an arrangement or compromise with its creditors
     under any statute or otherwise; (iv) is subject to a proceeding in
     bankruptcy, receivership, liquidation or insolvency and same is not
     dismissed within thirty (30) days; (v) makes an assignment for the benefit
     of the creditors; (vi) admits in writing its inability to pay its debts as
     they mature; or (vii) ceases to function as a going concern or to conduct
     its operations in the normal course of business.




                                      12
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

16.4 If Williams defaults under this Agreement, and does not cure such default
     within thirty (30) days of receipt of Sycamore's written notice, Sycamore
     shall have the right to take any or all of the following actions: (i)
     declare this Agreement to be in default and all amounts payable under this
     Agreement shall become immediately due and payable; (ii) suspend delivery
     to Williams until the default is cured by Williams; (iii) proceed by court
     action to enforce performance and/or recover damages; and/or (iv) terminate
     this Agreement. If Sycamore continues to make shipments after Williams
     default, Sycamore's action shall not constitute a waiver of any rights or
     remedies, or affect Sycamore's legal remedies under this Agreement.

     If Sycamore defaults under this Agreement, and does not cure such default
     within thirty (30) days of receipt of Williams' written notice, Williams
     shall have the right to take any or all of the following actions: (i)
     declare this Agreement to be in default and all amounts payable under this
     Agreement shall become immediately due and payable for all products
     delivered and services performed prior to such termination; (ii) proceed by
     court action to enforce performance and/or recover damages; and/or (iii)
     terminate this Agreement. If Williams continues to order Products after
     Sycamore's default, Williams' action shall not constitute a waiver of any
     rights or remedies, or affect Williams' legal remedies under this
     Agreement.

16.5 The termination or expiration of this Agreement shall in no case relieve
     either party from its obligation to pay to the other any sums accrued under
     this Agreement prior to such termination or expiration.

17.  General
     -------

17.1 Entire Agreement; Amendment; Authorized Personnel.  This Agreement
     --------------------------------------------------
     supersedes all prior and contemporaneous agreements, representations,
     warranties and understandings and contains the entire agreement between the
     parties.  No amendment, modification, termination, or waiver of any
     provision of this Agreement or consent to any departure from this Agreement
     shall be effective unless it is in writing and signed by a duly authorized
     representative of each party.  No failure or delay on the part of either
     party in exercising any right or remedy under this Agreement shall operate
     as a waiver of such right or remedy.

17.2 Assignment.  This Agreement shall be binding upon and inure to the benefit
     -----------
     of the parties and their respective successors and assigns, but neither
     party shall have the right to assign or otherwise transfer its rights under
     this Agreement without receiving the express prior written consent of the
     other party, such consent not to be unreasonably withheld..   Either party
     may, however, assign this Agreement in the event of a sale of all or
     substantially all of such party's assets or stock to which assignment the
     both parties consent to now.  Notwithstanding the foregoing, Williams may
     assign this Agreement to any entity controlling, controlled by, or under
     common control with Williams. Williams shall notify Sycamore in writing of
     such assignment within a reasonable time thereafter.

17.3 Notices.  All notices, requests, demands, and other communications provided
     --------
     for under this Agreement shall be in writing and in English to be sent by
     registered or certified mail, postage prepaid, to the receiving party at
     its address as set forth in this Agreement or to any other address


                                      13
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

     that the receiving party may have provided to the sending party in writing.
     When feasible, any such notice, request, demand or other communication
     shall also be transmitted by facsimile as follows or to such other
     facsimile number as provided by the receiving party in writing:

            .  Williams Facsimile Number: (918) 573-6578
               ATTN: Contract Administration.

            .  Sycamore's Facsimile Number: ___________________
               ATTN:  General Counsel


     Any notice, request, demand or other communication sent by facsimile will
     be deemed to have been received on the day it is sent.  Any notice,
     request, demand or other communication sent by registered or certified mail
     will be deemed to have been received on the seventh (7th) business day
     after its date of posting, unless it is sent by facsimile prior to such
     seventh (7th) business day.

17.4 Governing Law. This Agreement and all acts and transactions pursuant hereto
     --------------
     and the rights and obligations of the parties hereto shall be governed,
     construed and interpreted in accordance with the laws of the State of New
     York. The United Nations Convention on Contracts for the International Sale
     of Goods is specifically excluded from application to this Agreement.

17.5 Counterparts; Severability; and Headings.  This Agreement may be executed
     -----------------------------------------
     in any number of counterparts, each of which when executed and delivered
     shall be deemed to be an original and all of which taken together shall
     constitute one and the same instrument.  The provisions of this Agreement
     are declared to be severable.  In the event that any provision contained in
     this Agreement shall be held to be unenforceable or invalid, the remaining
     provisions shall be given full effect, and the parties agree to negotiate,
     in good faith, a substitute valid provision which most nearly approximates
     the parties' intent.  The failure of either party in any one or more
     instances to enforce any of the terms of this Agreement shall not be
     construed as a waiver of future enforcement of that or any other term.
     Headings in this Agreement are included for reference only and shall not
     constitute a part of this Agreement for any other purpose.

17.6 Force Majeure.  Neither party shall be held responsible for any delays or
     --------------
     failure in performance caused in whole or in part by fires, strikes,
     floods, embargoes, labor disputes, delays or failures of subcontractors,
     acts of sabotage, riots, accidents, delays of carriers, voluntary or
     mandatory compliance with any governmental act, regulation or request, acts
     of God or by public enemy, or any other causes beyond the party's
     reasonable control.  If such contingency shall occur, the defaulting party
     may elect to either (a) suspend this Agreement for the duration of the
     delaying cause, or (b) extend the duration of this Agreement by the length
     of time the contingency endured, or the non-defaulting party may terminate
     this Agreement upon giving ninety (90) days prior written notice.


                                      14
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                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

17.7  Survival.  The parties agree that the provisions of the following
      ---------
      Sections shall survive the expiration or earlier termination of this
      Agreement for any reason: License of Software Products and Firmware,
      Patent and Copyright Indemnification, Limitation of Liability, and
      Confidentiality.

17.8  Training Services. Sycamore will provide at no charge to Williams, two (2)
      one (1) - week sessions of on-site operational training of up to twenty
      (20) students per class. Such classes will be provided on dates mutually
      agreed to by the parties.


17.9  Escrow Program. Sycamore agrees to deposit Source Code, at Williams'
      expense, into Sycamore's Escrow Program, under an Escrow Agreement
      mutually agreed to by the parties, upon William's notice that it wishes an
      escrow deposit to be made. A sample of Sycamore's Escrow Agreement is
      attached hereto as Exhibit D.

17.10 Insurance.  Sycamore agrees to maintain, at all times during the term of
      this Agreement, insurance in accordance with the terms and conditions of
      Exhibit C hereto and incorporated herein by reference. Sycamore agrees
      that under its insurance policies Williams will be named as an
      additional insured.

17.11 Prevailing Party.  In any action or proceeding to enforce rights or
      obligations under this  Agreement, the prevailing party shall be entitled
      to recover court costs and reasonable attorney's fees.

17.12 Time and Material Charges.  If Sycamore invoices Williams time and
      material charges for services provided, Sycamore agrees to provide
      documentation to substantiate such charges.

17.13 Conflict of Interest.  Sycamore will not pay any commissions, fees or
      rebates to any employees of Williams, nor favor any employee of Williams
      with gifts or entertainment.  If Williams has reasonable cause to believe
      that one of this provision has been violated, Sycamore agrees to cooperate
      with Williams in its investigation.

17.14 Marketing. Sycamore and Williams agree to engage in joint marketing and
      advertising activities as mutually agreed to by the parties. The amounts
      spent on the joint marketing activities will be based on the amount of
      purchases made by Williams hereunder at a contribution percentage to be
      mutually determined by the parties within the first twelve months of this
      Agreement.


                                      15
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

IN WITNESS WHEREOF, the parties have caused this Agreement to be executed in
duplicate by their duly authorized representatives as of the effective date
written below.


SYCAMORE NETWORKS, INC.       WILLIAMS COMMUNICATIONS, INC.

By:  /s/ Despande                    By:  /s/ Joseph P. [illegible]
     ----------------------------         -------------------------------


Name:     Despande                  Name:
     ----------------------------         -------------------------------


Title:            Chairman          Title:
     ----------------------------         -------------------------------


Effective Date:    March 5, 1999    Date:
                -----------------         -------------------------------




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                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>


                                   EXHIBIT A
                                       to
                    SYCAMORE PURCHASE AND LICENSE AGREEMENT


                        ADDITIONAL TERMS AND CONDITIONS
                        --------------------------------

a)   Williams represents and agrees that Sycamore's has been chosen as an
     approved vendor to Williams to supply WDM Transponder Technology.  The Term
     (the "Term") of the Definitive Agreement shall be for three (3) years.  In
     year one of the Term, Williams agrees to a minimum purchase of ten million
     dollars ($10,000,000) net invoice value, in Sycamore product. This revenue
     commitment is based on Williams Planning Engineering 1999 scheduled build
     out plans for Transponder based systems in Spur locations. Williams
     commitment is an estimate only and Williams shall have no liability or
     penalty for failure to purchase this amount.

b)   Williams shall, have a nontransferable right to purchase shares of Sycamore
     in Sycamore's initial public offering (IPO) of shares on a national
     exchange to an upper limit, unless otherwise agreed, equal to that number
     of shares, which when multiplied by the IPO price as listed on the cover
     page of the final prospectus relating to Sycamore's IPO, equals 5% of the
     dollar value of Williams' accumulated purchases of products and services,
     (less any applicable discounts, taxes or charges for shipping, insurance,
     and the like), made by Williams as of the date of the IPO, but in no event
     more than 5% of the shares offered in such IPO.

c)   Sycamore, as additional discount hereunder agrees to grant to Williams a
     credit against future purchases by Williams under this Agreement, an amount
     equal to [**]% of the net purchase price of sales of Sycamore Products SN
     6000/8001 made to future customers prior to December 31, 1999. This credit
     may be used for the purchase of Sycamore Products under this agreement only
     and is not redeemable in any other matter. Upon expiration or termination
     of this Agreement any unused portion of the credit will expire.

d)   Upon completing a successful implementation of Sycamore product into
     Williams network, Sycamore and Williams agree to engage in joint press
     activity to the mutual benefit of both companies. The level of activity and
     timing of any announcements will be by mutual agreement.

e)   Any adjustment of the discount to which Williams is entitled, except for
     corrections to mathematical or administrative errors in the computation of
     such discount, shall not be retroactive with regard to Products purchased
     and delivered prior to the adjustment of such discount.

f)   In the event of a release from escrow of the Materials deposited, Williams
     agrees that such material shall be maintained as Sycamore's Confidential
     and Trade Secret Information and shall only be used for the purpose of
     maintaining Williams' installed base of Sycamore Products by Williams or,
     if Williams so elects, a third party agreed to in writing by Sycamore,
     provided said third party is bound by the same confidentiality and use
     restrictions as Williams. Sycamore shall not unreasonably withhold or delay
     such agreement. If Sycamore is no longer operating its business, such
     consent will not be required.


                                      17
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

                                   EXHIBIT B
                                      to
                    SYCAMORE PURCHASE AND LICENSE AGREEMENT

                             Pricing and Discounts
                             ---------------------


Sycamore agrees, during the term of this Agreement to extended a [**] product
discount on Sycamore's then-current end-user pricing in effect as of the date of
Williams' orders.

Sycamore represents that [**]. In the event that Sycamore [**].



                                      18
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

                                   EXHIBIT C
                                      to

                    SYCAMORE PURCHASE AND LICENSE AGREEMENT

                                INSURANCE TERMS

[NOTE:  Sycamore's insurance binder to be attached.]


                                      19
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

                                   EXHIBIT D
                                      to

                    SYCAMORE PURCHASE AND LICENSE AGREEMENT

                              YEAR 2000 Statement


Sycamore Year 2000 (Y2K) Compliance
Corporate Statement

     Sycamore Networks recognizes the genuine and particular concerns of the
telecommunications industry with regard to Year 2000 performance issues and is
committed to ensure that Sycamore's Products meet the requirements of Sycamore's
customers in this critical area.

     Sycamore Networks commits that its Products will comply with
telecommunications industry Year 2000 standards as set forth in each applicable
Product specification.

     More specifically, to the extent that any Sycamore Software or Products
report or utilize dates, all such Software and Products, will be Year 2000
compliant and will meet telecommunication industry Year 2000 standards.
SYCAMORE shall ensure that any SYCAMORE provided programs or systems with which
its Software communicates or integrates and which utilize dates, are Year 2000
compliant and, If requested by Sycamore's Customer, Sycamore shall provide the
Customer with results of Year 2000 compliance tests previously conducted or will
agree to jointly conduct mutually agreed to Year 2000 compliance tests with the
Customer.

     In the event the Products or Software do not comply or such tests
demonstrate that Sycamore's Software or Sycamore's Products are not Year 2000
compliant, as provided herein, Sycamore's obligation shall be to carry out or
procure the carrying out of all necessary enhancements or upgrades to the
Software or the Products at its own cost at Sycamore's manufacturing facility.

     Sycamore shall not be obligated to make enhancements or upgrades in the
event such tests demonstrate that the Year 2000 non-compliance results from non-
Sycamore supplied programs or systems, or from Sycamore's compliance with an
industry standard specification in effect as of the date of manufacture.

     The preceding statement is made pursuant to the United States Year 2000
Information and Readiness Disclosure Act (Public Law 105-271; 112 Stat. 2386).



                                      20
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

                                   EXHIBIT E
                                       to

                    SYCAMORE PURCHASE AND LICENSE AGREEMENT


                          THREE-PARTY ESCROW AGREEMENT


                                    BETWEEN


                    PRODUCER, FORT KNOX AND SINGLE LICENSEE


This is an Example:
-------------------

     This escrow agreement is intended for use by a Producer (Licensor), a
single Licensee (End User) and Fort Knox Escrow Services, Inc.  Any number of
escrow products may be stored in escrow for the Licensee under the terms of this
agreement.  All parties sign the contract.

                           Software Escrow Agreement

     This Escrow Agreement ("Agreement") is made as of this ___ day of
_________________, 199__, by and between _____________________________________
("Producer"), Fort Knox Escrow Services, Inc. ("Fort Knox") and
________________________________________________________________________________
______________ (Licensee").

     Preliminary Statement.  Producer intends to deliver to Fort Knox a sealed
     ---------------------
package containing magnetic tapes, disks, disk packs, or other forms of media,
in machine readable form, and the written documentation prepared in connection
therewith, and any subsequent updates or changes thereto (the "Deposit
Materials") for the computer software products (the "System(s)"), all as
identified from time to time on Exhibit B hereto.  Producer desires Fort Knox to
hold the Deposit Materials, and, upon certain events, deliver the Deposit
Materials (or a copy thereof) to Licensee, in accordance with the terms hereof.

     Now, therefore, in consideration of the foregoing, of the mutual promises
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties agree as
follows:

     1.   Delivery by Producer.  Producer shall be solely responsible for
          --------------------
delivering to Fort Knox the Deposit Materials as soon as practicable.  Fort Knox
shall hold the Deposit Materials in accordance with the terms hereof.  Fort Knox
shall have no obligation to verify the completeness or accuracy of the Deposit
Materials.




                                      21
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

     2.  Duplication; Updates.
         --------------------

     (a) Fort Knox may duplicate the Deposit Materials by any means in order to
comply with the terms and provisions of this Agreement, provided that Licensee
shall bear the expense of duplication. Alternatively, Fort Knox, by notice to
Producer, may reasonably require Producer to promptly duplicate the Deposit
Materials.

     (b) Producer shall deposit with Fort Knox any modifications, updates, new
releases or documentation related to the Deposit Materials by delivering to Fort
Knox an updated version of the Deposit Materials ("Additional Deposit") as soon
as practicable after the modifications, updates, new releases and documentation
have been developed by Producer.  Fort Knox shall have no obligation to verify
the accuracy or completeness of any Additional Deposit or to verify that any
Additional Deposit is in fact a copy of the Deposit Materials or any
modification, update, or new release thereof.

     3.  Notification of Deposits.  Simultaneous with the delivery to Fort Knox
         ------------------------
of the Deposit Materials or any Additional Deposit, as the case may be, Producer
shall deliver to Fort Knox and to Licensee a written statement specifically
identifying all items deposited and stating that the Deposit Materials or any
Additional Deposit, as the case may be, so deposited have been inspected by
Producer and are complete and accurate. Fort Knox shall, within ten (10)
business days of receipt of any Deposit Materials, send notification to Producer
and Licensee that it has received from Producer such Deposit Materials.

     4.  Delivery by Fort Knox
         ---------------------

         4.1  Delivery by Fort Knox to Licensee.  Fort Knox shall deliver the
              ---------------------------------
Deposit Materials, or a copy thereof, to Licensee only in the event that:

     (a) Producer notifies Fort Knox to effect such delivery to Licensee at a
specific address, the notification being accompanied by a check payable to Fort
Knox in the amount of one hundred dollars ($100.00); or

     (b) Fort Knox receives from Licensee:

         (i)   the occurrence of one of the following escrow release events:

               (1) the making by Producer of a general assignment for the
               benefit of creditors and the unwillingness or inability of
               Producer to provide support for the licensed software;

               (2) any action by Producer under any federal or state insolvency
               or similar law for the purpose of its bankruptcy, reorganization
               or liquidation and the unwillingness or inability of Producer to
               provide support for the licensed software;

               (3) Producer's failure to continue in business without a
               successor and the unwillingness or inability of Producer to
               provide support for the licensed software;



                                      22
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

          (ii)  evidence satisfactory to Fort Knox that Licensee has previously
                notified Producer of such Producer Default in writing;

          (iii) a written demand that the Deposit Materials be released and
                delivered to Licensee;

          (iv)  a written undertaking from the Licensee that the Deposit
                Materials being supplied to the Licensee will be used only as
                permitted under the terms of the License Agreement;

          (v)   specific instructions from the Licensee for this delivery; and

          (vi)  an initial check payable to Fort Knox in the amount of one
                hundred dollars ($100.00).

     (c) If the provisions of paragraph 4.1(a) are satisfied, Fort Knox shall,
within five (5) business days after receipt of the notification and check
specified in paragraph 4.1(a), deliver the Deposit Materials in accordance with
the applicable instructions.

     (d) If the provisions of paragraph 4.1(b) are met, Fort Knox shall, within
five (5) business days after receipt of all the documents specified in paragraph
4.1(b), send by certified mail to Producer a photostatic copy of all such
documents.  Producer shall have thirty (30) days from the date on which Producer
receives such documents ("Objection Period") to notify Fort Knox of its
objection ("Objection Notice") to the release of the Deposit Materials to
Licensee and to request that the issue of Licensees entitlement to a copy of
the Deposit Materials be submitted to arbitration in accordance with the
following provisions:

         (i)   If Producer shall send an Objection Notice to Fort Knox during
               the Objection Period, the matter shall be submitted to, and
               settled by arbitration by, a panel of three (3) arbitrators
               chosen by the Atlanta Regional Office of the American Arbitration
               Association in accordance with the rules of the American
               Arbitration Association.  The arbitrators shall apply Georgia
               Law.  At least one (1) arbitrator shall be reasonably familiar
               with the computer software industry.  The decision of the
               arbitrators shall be binding and conclusive on all parties
               involved, and judgment upon their decision may be entered in a
               court of competent jurisdiction.  All costs of the arbitration
               incurred by Fort Knox, including reasonable attorneys' fees and
               costs, shall be paid by the party which does not prevail in the
               arbitration; provided, however, if the arbitration is settled
               prior to a decision by the arbitrators, the Producer and Licensee
               shall each pay 50% of all such costs.

         (ii)  Producer may, at any time prior to the commencement of
               arbitration proceedings, notify Fort Knox that Producer has
               withdrawn the Objection Notice.  Upon receipt of any such notice
               from Producer, Fort Knox shall reasonably promptly deliver the
               Deposit Materials to Licensee in accordance with the instructions
               specified in paragraph 4.1(b)(v).



                                      23
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

     (e)  If, at the end of the Objection Period, Fort Knox has not received an
Objection Notice from Producer, then Fort Knox shall reasonably promptly deliver
the Deposit Materials to Licensee in accordance with the instructions specified
in paragraph 4.1(b)(v).  Both Producer and Licensee agree that Fort Knox shall
not be required to deliver such Deposit Materials until all such fees then due
Fort Knox have been paid.

          4.2  Delivery by Fort Knox to Producer.  Fort Knox shall release and
               ---------------------------------
deliver the Deposit Materials to Producer upon termination of this Agreement in
accordance with paragraph 7(a) hereof.

     5.   Indemnity.  Producer and Licensee shall, jointly and severally,
          ---------
indemnify and hold harmless Fort Knox and each of its directors, officers,
agents, employees and stockholders ("Fort Knox Indemnities") absolutely and
forever, from and against any and all claims, actions, damages, suits,
liabilities, obligations, costs, fees, charges, and any other expenses
whatsoever, including reasonable attorneys' fees and costs, that may be asserted
against any Fort Knox Indemnitee in connection with this Agreement or the
performance of Fort Knox or any Fort Knox Indemnitee hereunder.

     6.   Disputes and Interpleader.
          -------------------------

     (a) Fort Knox may submit the matter to any court of competent jurisdiction
in an interpleader or similar action other than a matter submitted to
arbitration after Fort Knox's receipt of an Objection Notice under Section 4 and
the parties under this Agreement submit the matter to such arbitration as
described in Section 4 of this Agreement.  Any and all costs incurred by Fort
Knox in connection therewith, including reasonable attorneys' fees and costs,
shall be borne 50% by each of Producer and Licensee.

     (b) Fort Knox shall perform any acts ordered by any court of competent
jurisdiction, without any liability or obligation to any party hereunder by
reason of such act.

     7.   Term and Renewal.
          ----------------

     (a) The initial term of this Agreement shall be two (2) years, commencing
on the date hereof (the "Initial Term"). This Agreement shall be automatically
extended for an additional term of one year ("Additional Term") at the end of
the Initial Term and at the end of each Additional Term hereunder unless, on or
before ninety (90) days prior to the end of the Initial Term or an Additional
Term, as the case may be, any party notifies the other parties that it wishes to
terminate the Agreement at the end of such term.

     (b) In the event of termination of this Agreement in accordance with
paragraph 7(a) hereof, Licensee shall pay all fees due Fort Knox and shall
promptly notify Producer that this Agreement has been terminated and that Fort
Knox shall return to Producer all copies of the Deposit Materials then in its
possession.

     8.   Fees.  Producer and Licensee shall pay to Fort Knox the applicable
          ----
fees in accordance with Exhibit A as compensation for Fort Knox's services under
this Agreement.  The first years fees are due upon receipt of the signed
contract or Deposit Materials, whichever comes first and shall be paid in U.S.
Dollars.

     (a)  Payment.  Fort Knox shall issue an invoice to Licensee following
          -------
execution of this Agreement ("Initial Invoice"), on the commencement of any
Additional Term  hereunder, and in connection



                                      24
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

with the performance of any additional services hereunder. Payment is due upon
receipt of invoice. All fees and charges are exclusive of, and Licensee is
responsible for the payment of, all sales, use and like taxes. Fort Knox shall
have no obligations under this Agreement until the Initial Invoice has been paid
in full by Licensee.

     (b) Nonpayment.  In the event of non-payment of any fees or charges
         ----------
invoiced by Fort Knox, Fort Knox shall give notice of non-payment of any fee due
and payable hereunder to the Licensee and, in such an event, the Licensee shall
have the right to pay the unpaid fee within ten (10) days after receipt of
notice from Fort Knox.  If Licensee fails to pay in full all fees due during
such ten (10) day period, Fort Knox shall give notice of non-payment of any fee
due and payable hereunder to Producer and, in such event, Producer shall have
the right to pay the unpaid fee within ten (10) days of receipt of such notice
from Fort Knox.  Upon payment of the unpaid fee by either the Producer or
Licensee, as the case may be, this Agreement shall continue in full force and
effect until the end of the applicable term. Failure to pay the unpaid fee under
this paragraph 8(b) by both Producer and Licensee shall result in termination of
this Agreement.

     9.  Ownership of Deposit Materials.  The parties recognize and acknowledge
         ------------------------------
that ownership of the Deposit Materials shall remain with Producer at all times.

     10. Available Verification Services.  Upon receipt of a written request
         -------------------------------
from Licensee, Fort Knox and Licensee may enter into a separate agreement
pursuant to which Fort Knox will agree, upon certain terms and conditions, to
inspect the Deposit Materials for the purpose of verifying its relevance,
completeness, currency, accuracy and functionality ("Technical Verification
Agreement").  Upon written request from Producer, Fort Knox will issue to
Producer a copy of any written technical verification report rendered in
connection with such engagement.  If Fort Knox and Licensee enter into such
Technical Verification Agreement, Producer shall reasonably cooperate with Fort
Knox by providing its facilities, computer systems, and technical and support
personnel for technical verification whenever reasonably necessary.  If
requested by Licensee, Producer shall permit one employee of Licensee to be
present at Producer's facility during any such verification of the Deposit
Materials.

     11. Bankruptcy.  Producer and Licensee acknowledge that this Agreement is
         ----------
an "agreement supplementary to" the License Agreement as provided in Section 365
(n) of Title 11, United States Code (the "Bankruptcy Code").  Producer
acknowledges that if Producer as a debtor in possession or a trustee in
Bankruptcy in a case under the Bankruptcy Code rejects the License Agreement or
this Agreement, Licensee may elect to retain its rights under the License
Agreement and this Agreement as provided in Section 365 (n) of the Bankruptcy
Code.  Upon written request of Licensee to Producer or the Bankruptcy Trustee,
Producer or such Bankruptcy Trustee shall not interfere with the rights of
Licensee as provided in the License Agreement and this Agreement, including the
right to obtain the Deposit Material from Fort Knox.


                                      25
                 CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                 -------------------------------------------
                            SYCAMORE NETWORKS, INC.
                            ----------------------
<PAGE>

     12.  Miscellaneous.
          -------------

     (a) Remedies.  Except for intentional misrepresentation, gross negligence
         --------
or intentional misconduct, Fort Knox shall not be liable to Producer or to
Licensee for any act, or failure to act, by Fort Knox in connection with this
Agreement.  Any liability of Fort Knox regardless of the cause shall be limited
to the fees exchanged under this Agreement.  Fort Knox will not be liable for
special, indirect, incidental or consequential damages hereunder.

     (b) Natural Degeneration; Updated Version.  In addition, the parties
         -------------------------------------
acknowledge that as a result of the passage of time alone, the Deposit Materials
are susceptible to loss of quality ("Natural Degeneration"). It is further
acknowledged that Fort Knox shall have no liability or responsibility to any
person or entity for any Natural Degeneration.  For the purpose of reducing the
risk of Natural Degeneration, Producer shall deliver to Fort Knox a new copy of
the Deposit Materials at least once every three years.

     (c) Permitted Reliance and Abstention.  Fort Knox may rely and shall be
         ---------------------------------
fully protected in acting or refraining from acting upon any notice or other
document believed by Fort Knox in good faith to be genuine and to have been
signed or presented by the proper person or entity.  Fort Knox shall have no
duties or responsibilities except those expressly set forth herein.

     (d) Independent Contractor.  Fort Knox is an independent contractor, and is
         ----------------------
not an employee or agent of either the Producer or Licensee.

     (e) Amendments.  This Agreement shall not be modified or amended except by
         ----------
another agreement in writing executed by the parties hereto.

     (f) Entire Agreement.  This Agreement, including all exhibits hereto,
         ----------------
supersedes all prior discussions, understandings and agreements between the
parties with respect to the matters contained herein, and constitutes the entire
agreement between the parties with respect to the matters contemplated herein.
All exhibits attached hereto are by this reference made a part of this Agreement
and are incorporated herein.

     (g) Counterparts; Governing Law.  This Agreement may be executed in
         ---------------------------
counterparts, each of which when so executed shall be deemed to be an original
and all of which when taken together shall constitute one and the same
Agreement.  This Agreement shall be construed and enforced in accordance with
the laws of the State of Georgia.

     (h) Confidentiality.  Fort Knox will hold and release the Deposit Materials
         ---------------
only in accordance with the terms and conditions hereof, and will maintain the
confidentiality of the Deposit Materials.

     (i) Notices.  All notices, requests, demands or other communications
         -------
required or permitted to be given or made under this Agreement shall be in
writing and shall be delivered by hand or by commercial overnight delivery
service which provides for evidence of receipt, or mailed by certified mail,
return receipt requested, postage prepaid.  If delivered personally or by
commercial overnight delivery service, the date on which the notice, request,
instruction or document is delivered  shall be the date on which delivery is
deemed to be made, and if delivered by mail, the date on which such notice,
request, instruction or document is

                                      26
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------
<PAGE>

received shall be the date on which deliveryis deemed to be made. Any party may
change its address for the purpose of this Agreement by notice in writing to the
other parties as provided herein.

     (j) Survival.  Paragraphs 5, 6, 8, 9 and 12 shall survive any termination
         --------
of this Agreement.

     (k) No Waiver.  No failure on the part of any party hereto to exercise, and
         ---------
no delay in exercising any right, power or single or partial exercise of any
right, power or remedy by any party will preclude any other or further exercise
thereof or the exercise of any other right, power or remedy.  No express waiver
or assent by any party hereto to any breach of or default in any term or
condition of this Agreement shall constitute a waiver of or an assent to any
succeeding breach of or default in the same or any other term or condition
hereof.

     IN WITNESS WHEREOF each of the parties has caused its duly authorized
     officer to execute this Agreement as of the date and year first above
     written.

Fort Knox Escrow Services, Inc.

                   3539A Church Street                     Phone: 1-800-875-5669
                   Clarkston, Georgia  30021-1717          Fax:   1-404-298-2010
                   E-mail:  info@fortknoxescrow.com



          By:-------------------------- Title: --------------------------
          Print Name:----------------------------------------------------

Producer

          By:-------------------------- Title: --------------------------
          Print Name:----------------------------------------------------
          Address:-------------------------------------------------------

          Phone:---------------------------------------------------------
          Fax:-----------------------------------------------------------
          E-mail:--------------------------------------------------------

Licensee
          By:-------------------------- Title: --------------------------
          Print Name:----------------------------------------------------
          Address:-------------------------------------------------------

          Phone:---------------------------------------------------------
          Fax:-----------------------------------------------------------
          E-mail:--------------------------------------------------------


                                      27
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------
<PAGE>

                                   EXHIBIT A

                                  FEE SCHEDULE



Fees to be paid by Licensee shall be as follows:


     Initialization fee (one time only)                   $850
       ($765 for current clients)

     Annual maintenance/storage fee
       . includes two Deposit Material updates            $900
       . includes one cubic foot of storage space    (foreign $1,000)

     International (outside of U.S) - $1,000/product

     Additional Updates                                   $150
       (above two per year)

     Additional Storage Space                             $150/cubic foot



Payable by Licensee or Producer:


     Due Upon Licensee's or Producer's
     Request for Release of Deposit Materials             $100 for initial 2 hrs
                                                          $50/hour for
                                                          additional hours



A ten percent discount is credited towards the initialization fee for current
Fort Knox clients.  Fees due upon receipt of signed contract or Deposit
Material, whichever comes first and shall be paid in U.S. Dollars. Thereafter,
fees shall be subject to their current pricing, provided that such prices shall
not increase by more than 10% per year. An invoice for all renewal fees will be
issued on the anniversary of the initial invoice.


                                      28
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------
<PAGE>

                                   EXHIBIT B

B1.  Product Name: ____________________________________________________
     Version #:________________________________________________________


Prepared and Confirmed by:  ________________________________________________

Title:  _________________________________________   Date: __________________

Signature: _______________________________________________________________


Type of deposit:
----------------
          ____ Initial Deposit
          ____ Update Deposit to replace current deposits
          ____ Other (pleas describe)___________________________________________

Items Deposited:
----------------

    Quantity        Media Type         Description of Material

A)  ___________     ________________   _______________________

B)  ___________     ________________   _______________________

C)  ___________     ________________   _______________________


                         (please copy page as necessary)



                                      29
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------
<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

                                   EXHIBIT F

                                       to

                    SYCAMORE PURCHASE AND LICENSE AGREEMENT


                              MAINTENANCE OPTIONS

                           Sycamore Support Services

7 x 24 TAC Support Contract              Software Maintenance Contract
Resident Support Engineer Contract       Hardware Maintenance Contracts
Time & Material Order                    Return-to-Factory Repair Service
Standard Product Training                Customized Product Training


Support Packages:

     Basic:
            Includes:      Software Maintenance Contract
                           7 x 24 TAC Support Contract
            Package Price: [**] of End User Price


     Standard:
            Includes:      Software Maintenance Contract
                           7 x 24 TAC Support Contract
                           Hardware Maintenance Contract (Return/Repair)
            Package Price: [**] of  End User Price


     Premium:
            Includes:      Software Maintenance Contract
                           7 x 24 TAC Support Contract
                           Hardware Maintenance Contract (Advanced Exchange)
            Package Price: [**] of End User Price



                                      30
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------

<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

1.   7 x 24 TAC Support Contract

     1.1  Service Description:

          A. TAC Support includes 7 x 24 priority access to Sycamore's Technical
             Assistance Center. Priority support calls are routed to a Sycamore
             Network Support Engineer within ten (10) minutes during normal
             business hours and within twenty (20) minutes outside normal
             business hours.

          B. Sycamore Normal Business Hours:
             8:30 a.m. - 5:30 p.m. EST Monday thru Friday
             Excluding Sycamore Holidays

          C. Customers may call Sycamore's Technical Assistance Center Support
             toll-free number for technical support and problem diagnosis.

          D. Electronic access to Sycamore's bulletin board service via
             www.sycamorenet.com, provides Customers with: technical tips,
             software release notes, and problem status reports.

     1.2  Service Eligibility:

          A. Customer must possess a valid Sycamore TAC Support Contract or
             Sycamore Software Maintenance Contract.

          B. Customer must be in good credit standing with Sycamore.

     1.3  Service Pricing:

          A la carte: [**] of List Price


                                      31
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------
<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

2.   Hardware Maintenance Contract (Return/Repair)

     2.1  Service Description:

          A. The Customer must make a request for return by contacting
             Sycamore's Technical Support Center (TAC) and requesting a Return
             Material Authorization (RMA). Access to the TAC is available Monday
             through Friday, between 8:30 a.m. and 5:30 p.m., Eastern Time.

          B. Sycamore shall repair or replace (at its option) the malfunctioning
             product and return a functioning product to the Customer's site
             within [**] days of Sycamore's receipt of the malfunctioning
             product.

     2.2  Service Eligibility:

          A. Customer must possess a valid Sycamore Hardware Maintenance Service
             Contract.

          B. Customer must be in good credit standing with Sycamore.

          C. Customer must obtain a Sycamore RMA number and must externally
             label the product packaging with the Sycamore RMA number. Any
             materials returned to Sycamore without prior authorization and
             proper labeling will be exempt from the stated Service Description.

     2.3  Service Pricing:

          A la carte: [**] of List Price


                                      32
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------

<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

3. Hardware Maintenance Contract (Advanced Exchange)

  3.1   Service Description:

     A. Sycamore provides an advanced exchange replacement product upon
        qualification of defect by Sycamore support personnel.

     B. The Customer must make a request for return by contacting Sycamore's
        Technical Support Center (TAC) and requesting a Return Material
        Authorization (RMA). Access to the TAC is available Monday through
        Friday, between 8:30 a.m. and 5:30 p.m., Eastern Time.

     C. All eligible advanced exchange RMA requests for replacement products
        received before 3:00 p.m., Eastern Time will be shipped for arrival at
        the Customer site the next business day.

     D. All eligible RMA requests made after 3:00 p.m. will be shipped the
        following day for delivery at the Customer site [**] business days from
        the date of the RMA request.

     E. Customer shall return the malfunctioning product to Sycamore within [**]
        days of receipt of the replacement product. Malfunctioning product not
        returned to Sycamore within [**] days of Customer's receipt of
        replacement product shall be invoiced at Sycamore's then-current list
        price.

     F. The replacement products are provided to Customer at no cost provided
        the replacement was due to malfunction or normal wear and tear of the
        product and not due to causes external to the product. Otherwise, the
        product is provided at the then-current Sycamore list price, plus
        shipping and handling costs.

  3.2   Service Eligibility:

     A. Customer must possess a valid Sycamore Hardware Maintenance Service
        Contract.

     B. Customer must be in good credit standing with Sycamore.

     C. Customer must obtain a Sycamore RMA number and must externally label the
        product packaging with the Sycamore RMA number. Any materials returned
        to Sycamore without prior authorization and proper labeling will be
        exempt from the stated Service Description.

  3.3    Service Pricing:

     A la carte: [**] of List Price

                                      33
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------
<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.

4. Return-to-Factory Repair Service

     4.1 Service Description:

         A. As a per incident service, Sycamore shall repair or replace (at its
            option) the malfunctioning product and return a functioning product
            to the Customer's site within [**] days of Sycamore's receipt of the
            malfunctioning product.

         B. Beyond the Standard Hardware Warranty period, Sycamore warrants its
            work performed for a period of [**] days from the date of shipment
            from Sycamore to the Customer.

     4.2 Service Eligibility:

         A. Customer must provide a purchase order or other form of acceptable
            payment (at Sycamore's discretion) prior to returning the defective
            product.

         B. Customer must be in good credit standing with Sycamore.

         C. Customer must obtain a Sycamore RMA number and must externally label
            the product packaging with the Sycamore RMA number. Any materials
            returned to Sycamore without prior authorization and proper labeling
            will be exempt from the stated Service Description.

     4.3 Service Pricing:

     Quoted by Sycamore TAC at time of service request.


                                      34
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------

<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.


5.   Software Maintenance Contract

     5.1 Service Description:

         A. All Sycamore software releases performed during the software
            maintenance period will be provided to the Customer at no additional
            charge.

         B. Sycamore will notify the Customer under contract of all generally
            available software releases.

         C. Sycamore may choose to distribute all software and documentation
            updates either electronically (www.sycamorenet.com) or on physical
            media (CD, diskette, tape, etc.).

         D. Release Notes outlining software modifications, known deficiencies
            and upgrade/installation procedures are provided as part of the
            service.

         E. User Documentation updates, if applicable, is provided as part of
            the service.

         F. Sycamore will provide revision and enhancement release information
            as it becomes available for general release, relating to
            availability of code corrections, work-around procedures and
            limitations of Covered Products.

         G. Periodic software problem status reports including information
            concerning software enhancements, bugs and documentation updates.

         H. Purchase of Software Maintenance Contract also includes 7 x 24 TAC
            Support Services.

     5.2 Service Eligibility:

         A. Customer must possess a valid Sycamore Software Maintenance Service
            Contract.

         B. Customer must be in good credit standing with Sycamore.

     5.3 Service Pricing:

         A la carte: [**] of List Price


                                      35
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------

<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.


6.   Resident Support Engineer Contract

     6.1 Service Description:

         A. Sycamore provides a full-time qualified support engineer on-site at
            the Customer's location.

         B. Sycamore Resident Engineer provides technical consultation, assists
            in problem isolation, assists in planning and executing network
            activities (e.g. installations, upgrades, etc.) and manages issue
            resolution with Customer and Sycamore personnel.

         C. Standard work-hours (# of hours and time-of-day) apply.  However,
            non-standard work hours can be scheduled on an as needed basis.

     6.2 Service Eligibility:

         A. Customer must purchase a Sycamore Resident Support Engineer
            Contract.

         B. Customer must be in good credit standing with Sycamore.

     6.3 Service Pricing:

         [**] / year


                                      36
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------

<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.


7.   Time & Material Order

     7.1 Service Description:

         A. Customer may contract Sycamore Support Engineer(s) for on-site
            installation, upgrade or problem isolation services.

         B. Customer must provide a description of work requested, date and time
            required, location and materials required.

     7.2 Service Eligibility:

         A. Customer must provide a purchase order or other form of acceptable
            payment (at Sycamore's discretion) prior to receiving service.

         B. Customer must be in good credit standing with Sycamore.

     7.3 Service Pricing:

         Contact Sycamore TAC for quotation based upon rates below:

         Hourly Labor Charges (portal-to-portal):
         Monday through Friday, 8:30 AM - 5:30 PM       $[**]
           All other times                              $[**]
         $[**] Minimum Labor Charge

         Travel Charges (distance Sycamore must travel):
         0-50 miles                           $[**]
         51-500                               $[**]
         501-1,000                            $[**]
         1,001-1,500                          $[**]
         1,501-3,000                          $[**]
         Greater than 3,000 miles              [**]



                                      37
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------

<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.


8.   Standard Product Training

     8.1 Service Description:

         A. Sycamore qualified instructor provides training on product
            installation, configuration, operations, management and diagnosis.

         B. Course materials (overheads, handouts, etc.) are provided to each
            student.

         C. Hands-on laboratory exercises are provided (if applicable).  All
            instructional equipment provided by Sycamore.

         D. Classes are offered at Sycamore Education facilities or can be
            brought directly to the customer's site (additional travel and
            expense charges will be applied).

     8.2 Service Eligibility:

         A. Customer must provide a purchase order or other form of acceptable
            payment (at Sycamore's discretion) prior to attending training.

         B. Customer must be in good credit standing with Sycamore.

     8.3 Service Pricing:

         Sycamore Facility:
        .Training Cost (per student):    $[**] per day

         Customer Location:
        .Training Cost (per student):    $[**] per day
        .Travel:                         $[**] per course delivered
        .Expenses:                       $[**] per day


                                      38
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------

<PAGE>

Confidential Materials omitted and filed separately with the Securities and
Exchange Commission. Asterisks denote omissions.


9.   Customized Product Training

     9.1 Service Description:

         A. Sycamore will modify existing or create new materials to provide
            Customer-specified training.

         B. Sycamore qualified instructor provides the customized training.

         C. Course materials (overheads, handouts, etc.) are provided to each
            student.

         D. Hands-on laboratory exercises are provided (if applicable).  All
            instructional equipment provided by Sycamore.

         E. Classes are offered at Sycamore Education facilities or can be
            brought directly to the customer's site (additional travel and
            expense charges will be applied).

     9.2 Service Eligibility:

         A. Customer must provide a purchase order or other form of acceptable
            payment (at Sycamore's discretion) prior to attending training.

         B. Customer must be in good credit standing with Sycamore.

     9.3 Service Pricing:

         Sycamore Facility:
        .Course Customization:                $[**] per hour ($[**] minimum)
         (estimate provided at time of request)
        .Training Cost (per student):         $[**] per day

         Customer Location:
        .Course Customization:                $[**] per hour ($[**] minimum)
         (estimate provided at time of request)
        .Training Cost (per student):         $[**] per day
        .Travel:                              $[**] per course
        .Expenses:                            $[**] per day



                                      39
                   CONFIDENTIAL AND PROPRIETARY INFORMATION OF
                   -------------------------------------------
                           SYCAMORE NETWORK, INC
                           ---------------------