Document:

COBBLESTONE COURT SHOPPING CENTER

                                 SALE AGREEMENT

         THIS SALE AGREEMENT is made and entered into as of 28th day of January,
2000,  by and  between  Nooney  Real  Property  Investors-Four,  L.P. a Missouri
Limited  Partnership  ("Seller")  and Farrington  Properties,  Inc., a Minnesota
corporation ("Buyer"), upon the following terms and conditions:

         1.       PROPERTY.  Seller agrees to sell and Buyer agrees to  purchase
certain land located  in  the  City/County of  Burnsville,  State of  Minnesota,
commonly known as Cobblestone  Court  Shopping  Center,  and  more  particularly
described in Exhibit  AA"  attached  hereto, and  all  rights and  appurtenances
relating  thereto (the "Property").  The sale of the Property  shall include all
existing  improvements thereon,  all personal  property owned by Seller and used
in the maintenance  and  operation  of  the  Property,  as  well  as  a  written
assignment of all of Seller's interest  in all of the  leases  and  all  service
and  maintenance contracts, equipment leases and other contracts  related to the
Property (the  "Contract"), all of which Seller warrants to be free of all liens
and  encumbrances,  except for the following encumbrances:  those  shown  on the
Commitment  for  Title Insurance, issued by  Commonwealth  Land Title  Insurance
Company  (the "Title Company"),  with an  effective  date of August 12,  1999 at
8:00 a.m.  (File No. 101894). The Contracts shall be assigned and assumed at the
Closing pursuant to an assignment and assumption agreement reasonably acceptable
to Seller and  Buyer,  which shall  provide  that  Seller is responsible for all
obligations under  the  Contracts  arising  prior  to  the Closing and  Buyer is
responsible  for all  obligations  under  the  Contracts arising on or after the
Closing.

         2. PURCHASE PRICE.  The total purchase price payable by Buyer to Seller
for the  Property  shall be FIVE  MILLION ONE  HUNDRED  THOUSAND  AND  NO/100THS
DOLLARS ($5,100,000.00) ("Purchase Price"), payable as follows:

             Earnest Deposit deliver to the Title Company
             with this Agreement, to be held in an interest-
             bearing trust account:                               $ 100,000.00

             Additional Earnest Deposit, to be delivered to
             the Title Company and held in the same interest-
             bearing trust account as the original Earnest
             Deposit, if Buyer elects to postpone the
             Closing pursuant to Section 8 below:                 $ 100,000.00

             Cash to be paid at Closing:                     The balance of the
                                                                Purchase Price

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         Except as may be provided  herein,  payment of the Purchase Price shall
be made by a wire transfer of immediately available federal funds.

         3.  EARNEST   DEPOSIT.   The  Earnest  Deposit  shall  be  held  in  an
interest-bearing  trust account with the Title Company under the Title Company's
standard  earnest  money escrow  agreement.  If the sale is closed,  the Earnest
Deposit shall be credited  against the Purchase Price. If the sale is not closed
by the date fixed  therefor,  the Earnest Deposit shall be forfeited or refunded
pursuant to the terms of this Agreement

         4. DUE DILIGENCE  PERIOD.  Buyer shall have fifteen (15) days after the
date hereof (the "Due Diligence  Period") to  investigate  and test the Property
and examine the  Contracts  and such  records and  documents  as Seller has made
available  to  Buyer  prior  to the  date  hereof  or  which  Seller  has in its
possession  and Buyer may  reasonably  request from  Seller.  Seller shall allow
Buyer,  and Buyer's agents,  access to the Property at all reasonable  times for
the purpose of Buyer's investigation and testing.  Buyer shall pay all costs and
expenses of such  investigation  and testing,  shall restore the  Property,  and
shall hold Seller and the Property harmless from all costs

                                       1

and  liabilities relating to Buyer's activities.  If Buyer is not satisfied with
the condition of the Property,  or  Buyer's  review  of  the  Contracts  or such
records and documents.  Buyer  may  terminate  this  Agreement by giving written
notice thereof to Seller on or before  the end of the Due  Diligence  Period, in
which event the Earnest Deposit and accrued interest  thereon  shall be refunded
to Buyer,  and neither  party shall have any  further  liability  hereunder.  If
Buyer  does not terminate this Agreement  on  or  before  the  end  of  the  Due
Diligence  Period,  Buyer's right to terminate  based  on the  condition  of the
Property or the contents of the Contracts or such records and documents shall be
deemed waived except as otherwise provided in Sections 11 and/or 12 hereof.

         5.  ESCROW.  At the  election  of either  Buyer or Seller,  and at such
party's expense,  the sale shall be closed in escrow in the offices of the Title
Company. Seller and Buyer shall deliver at Closing such evidence or documents as
may be reasonably  required by the other party or the Title  Company  evidencing
the status and  capacity  of Seller and Buyer,  the  authority  of the person or
persons who are executing the various documents on behalf of the parties to this
Agreement,  and such other  documents  and  instruments  as may be reasonably or
routinely  required by the Title  Company to consummate  the sale.  Seller shall
deliver at the Closing a standard  seller's  affidavit in a form  sufficient  to
permit the Title  Company  to delete  the  standard  exceptions  for  parties in
possession (except for tenants under the Contracts) and mechanic's liens.

         6. COSTS.  Seller shall pay:  (i) one-half (2) of the Closing  costs of
the Title Company (but not any costs for title insurance premiums or any special
endorsements);  (ii) costs of the  preparation  or copying of any due  diligence
documents required under this Agreement;  (iii) Broker's commissions;  (iv) deed
stamp tax; (v) the cost of the title commitment  referred to in Section 1 above,
(vi) costs of  recording  documents  required to  establish  title in the manner
required by this Agreement (excluding the cost of recording the Warranty Deed to

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be given by Seller under this  Agreement), and (vii) all other costs customarily
borne  by  sellers  of  real  property  in  the general  Minneapolis,  Minnesota
metropolitan area.

         Buyer shall pay:  (i)  one-half  (2) of the Closing  costs of the Title
Company;  (ii)  charges  for  any  title  insurance  premiums  and  any  special
endorsements;  (iii) costs of the preparation of any Buyer  Documents;  (iv) all
costs related to Buyer's  review of Seller's due diligence  documents,  (v) all,
sales  taxes or  similar  taxes and fees,  and all  recording  costs  (except as
provided in the  preceding  paragraph)  excluding  deed stamp tax;  and (vi) all
other  costs  customarily  borne  by  buyers  of real  property  in the  general
Minneapolis, Minnesota metropolitan area.

         7.  PRORATIONS.   All  utilities,   Contracts,  and  other  rights  and
obligations  of the  Property  commonly  prorated  upon  the  sale  of the  real
property, shall be prorated as of the date of Closing, on the basis of a 365-day
year.  Buyer  assumed to be the owner of the  Property  for the  entire  date of
Closing, both as to income and expenses.  Real estate taxes and assessments will
be prorated on a payable,  not assessed,  basis (i.e.  The real estate taxes and
assessments  to be prorated  upon Closing will be based on the amount due in the
calendar  year  2000.)  Unpaid  rents and other  charges  payable  to Seller (as
landlord of the Property),  which are thirty (30) days or less outstanding shall
be  prorated  as of the date of  Closing,  with  Seller to receive  full  credit
therefor,  unpaid rents and other charges delinquent over thirty (30) days shall
not be prorated but shall be collected by Seller.  Buyer shall  receive a credit
against the Purchase  Price for the amount of any  security  deposits or escrows
held by Seller for the benefit of any tenants or contractors in connection  with
the Property.  There shall be no  prorations  made with respect to any insurance
carried on or with respect to the Property. If any required prorations cannot be
calculated  accurately on the date of Closing, then the same shall be estimated,
based upon prior known  amounts;  all such  proration  obligations  to be final,
binding, and conclusive as of the Closing.

         8. CLOSING.  The sale shall close at office of the attorney for Buyer's
lender on the  business day closest to the date  forty-five  (45) days after the
end of the fifteen  (15)-day due  diligence  period set forth above,  or on such
earlier date as Buyer shall request on at least two (2) business days' notice to
Seller.  Buyer may postpone the Closing for up to an additional  forty-five (45)
days by giving  written notice thereof to Seller at least five (5) business days
before  the  end  of the  first  forty-five  (45)-day  period  described  in the
preceding sentence, provided Buyer simultaneously pays an additional $100,000.00
Earnest Deposit to the Title Company,  as provided above. Time is of the essence
for all obligations under this Agreement.

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         9. TITLE.  Seller shall convey title by special warranty deed,  subject
to general taxes and assessments payable in the current year and thereafter, and
subject to the  exceptions to title  referred to in items 9, 10, 12, 13 an 14 of
Schedule B to the Commitment for Title Insurance  referred to in Section 1 above
(collectively,  "Permitted  Exceptions").   Buyer  shall  use  the Title Company

<PAGE>

referred to in Section 1 above for  its  owner's  and  mortgagee's  policies  of
title  insurance.  Buyer  acknowledges that the easements described on Exhibit A
may  not  be appurtenant easements and shall rely on  the  Title  Company  alone
with respect to whether such easements are appurtenant  easements.  The  special
warranty  deed  given  by Seller at Closing  shall  be  deemed  to  include  the
acknowledgment set forth in the preceding sentence.

         10.      REPRESENTATIONS AND WARRANTIES.  Except as specifically
set forth in this Agreement,  Seller makes no representations or warranties with
respect to the  Property;  it being  acknowledged  that Buyer  shall  accept the
Property in its present AS IS  condition.  Seller  represents  and warrants that
Seller  has the legal  capacity  and  authority  to  execute  and  deliver  this
Agreement  and all  instruments  to  consummate  the  Closing of the sale of the
Property;  except as set forth in the Title Commitment,  Seller has no knowledge
that any person other than Seller has any right, title or interest in and to the
Property; that to the best of Seller's knowledge, there are no causes of action,
suits or judgments  against Seller or the Property which would delay or prohibit
the sale; there are no Contracts for and with respect to the Property which have
not been  disclosed  to Buyer in  writing,  and which  are or may  become a lien
against the Property or an obligation of the Buyer upon Closing; and to the best
of Seller's knowledge,  Seller has received no written notices of any pending or
threatened  condemnation,  disconnection  of  any  existing  utilities,  or  any
hazardous  substances  upon the  Property.  Seller  certifies  and warrants that
Seller does not know of any "wells" on the Property  within the meaning of Minn.
Stat. ss. 1031; this  representation  is intended to satisfy the requirements of
that statute.  Solely for purposes of satisfying the requirements of Minn. Stat.
ss.115.55  Seller  represents  that  there is no  "individual  sewage  treatment
system"  (within the meaning of that statute) on or serving the Property.  Buyer
represents  and  warrants  that Buyer has the legal  capacity  and  authority to
execute and deliver this Agreement and all instruments to consummate the Closing
of the sale of the Property; and to the best of Buyer's knowledge,  there are no
causes of action, suits or judgments against Buyer which would delay or prohibit
the sale.

         11.  CONDITIONS TO CLOSE.  The following are conditions to the Closing:
(i) there shall be no material  change in the condition of the Property from the
Effective  Date  through the Closing  date with  respect to any matter of title;
(ii) all of the  representations  and  warranties  of Seller and Buyer  shall be
materially  true as of the date of  Closing;  (iii)  there  shall be no material
change in any law  affecting  the Property or any current use thereof;  and (iv)
Seller shall  deliver title to the Property to Buyer at Closing in the condition
required by Section 9 of this  Agreement.  If the foregoing  conditions  are not
satisfied  (or waived by Buyer) on or before the  Closing,  Buyer may  terminate
this  Agreement by giving  written  notice to Seller on or before the  scheduled
date of Closing, in which event the Earnest Deposit and accrued interest thereon
shall be refunded to Buyer and  neither  party shall have any further  liability
hereunder.

         12.      CASUALTY  AND  CONDEMNATION.    If  after  this  Agreement  is

<PAGE>

executed  the Property is  materially  damaged by casualty or Seller is notified
that all or a portion  of the  Property  shall be taken in  condemnation,  Buyer
shall have the right to terminate this Agreement, provided Buyer notifies Seller
in writing no later than thirty (30) days after Buyer receives actual  knowledge
of such casualty or notice of  condemnation,  in which event the Earnest Deposit
and all accrued  interest  thereon  shall be refunded to Buyer and neither party
shall  have  any  further  liability  hereunder.  In the  event  Buyer  fails to
terminate this  Agreement  within said thirty (30) days, it shall be deemed that
Buyer shall accept the Property  subject to such casualty  and/or  condemnation,
and Buyer shall be entitled to receive all insurance,  if any, carried by Seller
for and with respect to such damage, or as applicable, any condemnation award.

         13. DEFAULT.  In the event that the sale of the Property does not Close
because of Seller's  failure to perform any of  Seller's  obligation  under this
Agreement,  then Seller shall be in default hereunder.  In the event of any such
default,  Buyer shall have the right to terminate  this  Agreement  upon written
notice to Seller,  whereupon  the  Earnest  Deposit  together  with any  accrued
interest thereon shall be returned to Buyer. Alternatively, Buyer shall have the
right to exercise  any and all  remedies  which Buyer may have  against  Seller,
whether at law,  in equity or  pursuant  to this  Agreement  including,  without
limitation, the rights to compel specifically performance by Seller.

                                       3

         In the event that the sale of the  Property  does not Close  because of
Buyer's failure to perform any of Buyer's obligations under this Agreement, then
Buyer shall be in default hereunder. In the event any such default, Seller shall
have the  right to  terminate  this  Agreement  upon  written  notice  to Buyer,
whereupon the Earnest Deposit  together with any accrued  interest thereon shall
be delivered to Seller.  Alternatively,  upon any termination of this Agreement,
Seller shall have the right to exercise  any and all  remedies  which Seller may
have  against  Buyer,  whether at law, in equity or pursuant to this  Agreement,
including,  without  limitation,  the right to compel  specific  performance  by
Buyer.

         Notwithstanding  the  foregoing  provisions,  if either Buyer or Seller
become in  default of any term or  condition  of this  Agreement,  then prior to
either party  exercising its rights or remedies  permitted under this Agreement,
the party (the "Non-Defaulting  Party") claiming such default,  shall notify the
other party (the  "Defaulting  Party") in writing,  setting  forth in reasonable
details the nature of such default.  The  Defaulting  Party shall then have five
(5) business  days after receipt of such notice in which to cure such default to
the reasonable satisfaction of the Non-Defaulting Party. If the Defaulting Party
does not cure such default to the reasonable  satisfaction of the Non-Defaulting
Party  within the said five (5) business day period,  the  Non-Defaulting  Party
shall then have the full right to proceed with its  remedies as permitted  under
this Agreement.

         14. NOTICES. Any notices,  required or desired to be given hereunder by
any party  shall be in  writing  and shall be  validly  given or made to another
party if sent by facsimile or by a nationally  recognized  commercial  overnight
courier service,  or if  deposited  in  the United  States  mail,  certified  or

<PAGE>

registered,  postage   prepaid,   return   receipt   requested.   Any  facsimile
transmission  shall  be  followed  by  notice either  by  overnight  courier  or
certified or registered mail, as provided above.  Notice shall  be  deemed  made
on the  date of facsimile transmission, on the date of delivery to the overnight
courier or upon mailing in the manner provided above.

         Seller:

         Nooney Real Property Investors-Four, L.P.
         A Missouri Limited Partnership
         c/o Maxus Properties
         1100 Main, Suite 2100
         Kansas City, MO 64105
         Attention: President
         FAX NO. 816-221-1829

         Buyer:

         Farrington Properties, Inc.
         530 Ford Centre
         420 North Fifth Street
         Minneapolis, MN 55401
         Attention: Mr. Bradley J. Schafer
         FAX NO. 612-359-5858

         Any party may change its address for the purpose of  receiving  notices
by delivering written notice to the other party in the manner aforesaid.

         15. BROKER'S COMMISSIONS. The parties warrant that they have dealt with
no  broker  or other  person  claiming  a  commission  in  connection  with this
transaction  ("Broker") other than United Properties Brokerage LLC (representing
Seller) and none (representing Buyer); and each party shall hold the other party
harmless  for any  breach  of such  warranty.  Seller  shall be  liable  for any
commissions  payable  to  the  aforesaid   Broker(s).   Buyer  and  Seller  each
acknowledge  and  agree  that  no  Broker  to  this  transaction  has  made  any
representations  or warranties  with respect to the Property or the use thereof,
and each party hereby releases the Broker(s) from all liability  incurred by the
Buyer or Seller as a result of any  investigation  or failure to investigate the
Property, or the failure of this sale to Close.

                                       4

         16.  EFFECTIVE  DATE. The Effective Date of this Agreement shall be the
last date that all  signatures  and  required  initials  have been  secured from
Seller and Buyer.

         17.      INTENTIONALLY DELETED.

<PAGE>

         18.      MISCELLANEOUS.

                  (a)  Further  Assurances.  Each of the  parties  hereto at the
reasonable expense of the requesting party shall execute and deliver any and all
additional  papers,  documents,  and other assurances,  and shall do any and all
acts and things reasonably necessary in connection with the performance of their
obligations hereunder and to carry out the intent of the parties hereto.

                  (b)  Exhibits,  Schedules  and Other  Documents.  All exhibits
attached hereto and or otherwise  referred to herein are hereby  incorporated in
this Agreement by reference as though set forth at length.

                  (c) Separate  Counterparts.  This Agreement may be executed in
one or more  separate  counterparts,  each of  which  shall be  deemed  to be an
original,  and all of which  together  shall  constitute and be one and the same
instrument.

                  (d)  Invalidity  of  Provisions.  If  any  provision  of  this
Agreement  is found to be invalid  or  unenforceable  by any court of  competent
jurisdiction,  the invalidity or  unenforceability  of such provision  shall not
affect the validity and enforceability of the remaining provisions hereof.

                  (e)  Terms.  The term  "business  days"  shall mean the period
between  9:00  a.m.  and 5:00  p.m.  local  time of any day of the  year  except
Saturdays,  Sundays,  and  legal  holidays  as  established  by the  appropriate
authorities of the State of Minnesota. The plural shall constitute the singular,
and vice versa; the masculine shall constitute the feminine, and vice versa.

                  (f) Binding  Agreement.  This Agreement  shall be binding upon
and inure to the benefit of the heirs, successors and assigns in interest of the
parties hereto. However, the aforesaid shall not constitute the Seller's consent
to any assignment of this Agreement by Buyer,  all such consent being  expressly
denied  without  Seller's   separate  written  approval.   Notwithstanding   the
foregoing,  Seller hereby consents to one or more  assignments of this Agreement
by Buyer or its assignees at or before the Closing to one or more  affiliates of
the  Buyer  so  long  as  such  assignee  or  assignees  fully  perform  Buyer's
obligations hereunder at Closing. No such assignments shall relieve the Buyer of
its  obligations  hereunder.  This Agreement  contains the entire  agreement and
understanding  between the parties,  and all prior agreements and understandings
regarding the subject mater of this  Agreement are merged  herein.  No addition,
modification  or amendment of any term or provision of this  Agreement  shall be
effective,  unless it is in writing and is signed by both Buyer and Seller.  All
representations  and warranties  contained in this  Agreement  shall survive the
Closing for a period of one (1) year.

                  (g)      Mutual Indemnification.  Seller shall indemnify  and
hold  Buyer  harmless from all liabilities (including reasonable attorneys' fees

<PAGE>

in defending against claims) arising out of claims by third parties relating  to
acts  or occurrences  on,  at  or  with  respect  to  the  Property  (including,
without limitation, the leases and contracts  assigned to Buyer hereunder) which
accrue on or before the Closing.  Buyer shall indemnify and hold Seller harmless
from all liabilities (including reasonable attorneys' fees in defending  against
claims)  arising out of claims by third parties  relating to acts or occurrences
on, at or with  respect to the  Property  (including,  without  limitation,  the
leases  and  contracts  assigned  to Buyer  hereunder)  which  accrue  after the
Closing.

         19.  CONTINGENCY.  Buyer's  obligation  to close  the  purchase  of the
Property  is  contingent   upon  Seller   delivering  to  Buyer   subordination,
non-disturbance  and attornment  agreements (the "SNDA's") and estoppel  letters
(the  "Estoppels")  from all of the tenants of the Property in a form reasonably
required  by  Buyer's  lender.  If Seller is unable to deliver  such  SNDA's and
Estoppels to Buyer on or before the Closing,  Buyer may terminate this Agreement
by giving  written  notice to Seller on or before the scheduled date of Closing,
in which  event the  Earnest  Deposit  and  accrued  interest  thereon  shall be
refunded to Buyer and neither party shall have any further liability  hereunder.
If Buyer

                                       5

does not deliver the  SNDA's  and  Estoppels  to  Seller in the form required by
Buyer's lender on or before the end of the Due Diligence  Period  or  if  Seller
does not believe  Seller will be able to obtain the  execution of the SNDA's and
the  Estoppels in such form from all of the tenants of the  Property, Seller may
terminate  this  Agreement by giving  written  notice to Buyer on or  before the
end of the Due Diligence  Period, in which event the Earnest Deposit and accrued
interest thereon shall be refunded to  Buyer  and  neither  party shall have any
further liability  hereunder.  If this  Agreement is terminated for any  reason,
Buyer  agrees  to  execute and deliver to Seller a quit claim deed releasing any
right, title or interest in the Property.

         WHEREFORE,  the parties have executed this  Agreement as of the day and
year first above written.

BUYER:                            SELLER:

FARRINGTON PROPERTIES, INC.       NOONEY REAL PROPERTY
                                  INVESTORS-FOUR, L.P.
                                  A Missouri Limited Partnership

By: /s/Bradley J. Shafer          By: /s/Daniel W. Pishny

Title: Secretary                  Title: President of Maxus Capital Corp., G.P.

Date: 1/28/2000                   Date: 1-28-00

                                        6

<PAGE>

                                    EXHIBIT A

                          Legal Description of Property

Lot 4, Block 2,  Federal  Land  Company  First  Addition,  according to the plat
thereof  now on file and of record in the office of the County  Recorder  within
and for Dakota County, Minnesota.

Together  with a permanent  easement per Document No.  543023 filed of record on
August  10,  1979,  Dakota  County  Recorder,  for storm  sewer and for  Utility
purposes  over,  under and  across a 10' wide  strip of land in Lot 3,  Block 2,
Federal Land Company  First  Addition,  according to the recorded  plat thereof,
being the Westerly 10' of the Easterly 20' of said Lot 3.

Together with and subject to a permanent  easement per Document No. 543022 filed
of record on August 10, 1979,  Dakota County Recorder for sanitary sewer and for
utility  purposes  over,  under and  across  that part of Lots 3 and 4, Block 2,
Federal  Land Company  First  Addition,  according to the recorded  plat thereof
lying Southwesterly of the following described line:

         Commencing  at the  Southerly  most corner of said Lot 3; thence  North
         61(degree)  25'  56"  West,  assumed  basis  for  bearings,  along  the
         Southwesterly  line of said Lot 3, a distance  of 155.52  feet;  thence
         North  28(degree) 34 04" East,  20.00 feet to the point of beginning of
         the line herein described; thence North 49(degree) 43' 29" West, 266.31
         feet to a point in a line 20.00 feet  Northeasterly  of,  measured at a
         right  angle  to the  Southwesterly  line  of said  Block  2 and  there
         terminating.

Together with and subject to:

Rights and  obligations of that  declaration of easements  dated March 27, 1981,
filed of record April 13, 1981, with the Dakota County Recorder, as Document No.
579350.

AND

Outlot D, Federal Land Company Second Addition, according to the plat thereof on
file  and of  record  in the  office  of the  County  Recorder,  Dakota  County,
Minnesota.

                                        7

<PAGE><PAGE>

                                                                     EXHIBIT 4.4

                                AMENDMENT NO. 2
                                       TO
                          SECOND AMENDED AND RESTATED
                           INVESTOR RIGHTS AGREEMENT
                           -------------------------

          This Amendment dated as of August 5, 1999 is entered into by and among
Sycamore Networks, Inc., a Delaware corporation (the "Company"), and the persons
and entities listed on Schedule I hereto.

          WHEREAS, the Company has entered into a Second Amended and Restated
Investor Rights Agreement dated as of February 26, 1999 and amended on July 23,
1999 (the "Agreement");

          WHEREAS, the Company and the requisite parties necessary to effect an
amendment to the Agreement pursuant to Section 7(b) thereof desire that the
Agreement be amended in the manner set forth below; and

          WHEREAS, the parties hereto desire to amend the Agreement pursuant to
this Amendment No. 2.

          NOW THEREFORE, in consideration of the mutual covenants contained
herein and for other valuable consideration, the receipt and sufficiency of
which is hereby acknowledged, the parties hereto agree as follows:

          1.  Section 2 of Article V of the Agreement is hereby amended to add
the word "parents" as persons to whom a Founder (as such term is defined in the
Agreement) may transfer shares of the capital stock of the Company.

          2.  The Agreement, as supplemented and modified by this Amendment,
together with the other writings referred to in the Agreement or delivered
pursuant thereto which form a part thereof, contain the entire agreement among
the parties with respect to the subject matter thereof and amend, restate and
supersede all prior and contemporaneous arrangements or understandings with
respect thereto.

          3.  Upon the effectiveness of this Amendment, on and after the date
hereof, each reference in the Agreement to "this Agreement," "hereunder,"
"hereof," "herein" or words of like import, and each reference in the other
documents entered into in connection with the Agreement, shall mean and be a
reference to the Agreement, as amended hereby.  Except as specifically amended
above, the Agreement shall remain in full force and effect and is hereby
ratified and confirmed.
<PAGE>

          4.  This Amendment shall be governed by the laws of the State of
Delaware, notwithstanding the conflict-of-law doctrines of Delaware or any other
jurisdiction to the contrary.

          5.  This Amendment may be executed in any number of counterparts, and
each such counterpart shall be deemed to be an original instrument, but all such
counterparts together shall constitute but one agreement.

          6.  This Amendment shall be binding on all parties to the Agreement as
and when executed by the Company, Founding Stockholders holding at least a
majority by voting power of the shares of capital stock held by the Founding
Stockholders and Investors holding at least a majority of the shares of Common
Stock issued or issuable upon conversion of the shares of the Series A Preferred
Stock and/or the Series B Preferred Stock and/or the Series C Preferred Stock
and/or the Series D Preferred Stock.

               [Remainder of this Page Intentionally Left Blank]

                                       2
<PAGE>

          IN WITNESS WHEREOF the parties hereto have executed this Amendment on
the date first above written.

                              COMPANY:

                              SYCAMORE NETWORKS, INC.

                              By: /s/ Daniel Smith
                                  ---------------------
                                  Daniel Smith
                                  President

                              Matrix Partners V, L.P.
                              Bay Colony Corporate Center
                              1000 Winter Street, Suite 4500
                              Waltham, Massachusetts 02154

                              By:   Matrix V Management Co., L.C.C.,
                                    its General Partner

                              By: /s/ Paul J. Ferri
                                  ---------------------

                              Matrix V Entrepreneurs Fund, L.P.
                              Bay Colony Corporate Center
                              1000 Winter Street, Suite 4500
                              Waltham, Massachusetts 02154

                              By:   Matrix V Management Co., L.C.C.,
                                    its General Partner

                              By /s/ Paul J. Ferri
                                 ----------------------

                              /s/ Gururaj Deshpande
                              ------------------------
                              Gururaj Deshpande

                              /s/ Daniel Smith
                              ------------------------
                              Daniel Smith

                                       3
<PAGE>

                              FOUNDING STOCKHOLDERS:

                              /s/ Gururaj Deshpande
                              ------------------------
                              Gururaj Deshpande

                              Address:   9 Sparta Way
                                         Andover, MA 01810

                              /s/ Richard Barry
                              ------------------------
                              Richard Barry

                              Address:   1284 Beacon Street, #815
                                         Brookline, MA 02138

                                       4
<PAGE>

                                   Schedule 1
                                   ----------

                                   Investors
                                   ---------

Matrix Partners V, L.P.
Matrix V Entrepreneurs Fund, L.P.
Gururaj Deshpande
Daniel Smith
Richard Barry

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