Document:

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                                                                   Exhibit 10.19

                            Sycamore Networks, Inc.

________________________________________________________________

                       MANUFACTURING SERVICES AGREEMENT

1.0  GENERAL SCOPE

This Manufacturing Services Agreement is entered into by and between Sycamore
Networks Inc. (Sycamore), 10 Elizabeth Drive, Chelmsford, Massachusetts 01824
and Jabil Circuit, Inc., ("Supplier"), having offices at 10560 9th Street North
St. Petersburg, Florida 33716 .

WITNESSETH:

WHEREAS, Sycamore desires to enter into a business relationship involving the
regular performance of two general classes of Manufacturing Services referred to
as "Non recurring" and "Recurring" services.

     Non-Recurring Manufacturing Services: generally associated with the initial
     introduction of new products including but not limited to; advanced circuit
     packaging development, test fixtures and test software for Printed Wiring
     Assemblies (PWAs), and product changes and rework of PWA's based on
     Sycamore "Engineering Change Orders" (ECOs). Any design or other services
     contemplated between the parties shall be governed by a separate services
     agreement agreed by the parties prior to the implementation of any such
     services.

     Recurring Manufacturing Services: includes volume production of products
     for Sycamore including but not limited to ; Recurring Material Procurement,
     assembly of PWAs, test and direct order fulfillment to defined Sycamore
     customers.

     Recurring Material Procurement: The activities involved to purchase
     material for Recurring Manufacturing Services.

     Affiliates: "Affiliate" means, with respect to a party hereto, a
     corporation that directly or indirectly controls, is controlled by or is
     under common control with that party.

     Days: in the context of this Agreement, DAY(S) refers to calendar days.

     Months: in the context of this Agreement, MONTH(S) refers to calendar
     months except in cases where a Sycamore fiscal months would apply, in which
     case a month shall mean a Sycamore fiscal month.

     Delivery Date: as defined on Sycamore Build Plan Forecasts indicates the
     date on which material is to arrive at Sycamore or designated "Ship To"
     address.

     Reasonable and Prudent Purchasing Practices: in the context of this
     Agreement indicates the minimization of Sycamore's liability for material
     through commercially reasonable efforts in initial procurement to secure
     return and/or cancellation rights and to return, cancel, resell, or use
     such materials elsewhere.
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     Currency: all currency defined in this agreement are in United States
     dollars.

     Specifications: in the context of this Agreement includes the bill of
     materials, designs, schematics, assembly drawings and test specifications
     provided by Sycamore to Supplier to manufacture products under this
     Agreement. Products will be considered to have met the required
     Specification once they pass Sycamore's defined production test procedures
     as agreed by the parties.

     [*] Created Intellectual Property: means any discoveries, inventions,
     technical information, procedures, manufacturing or other processes,
     software, firmware, technology, know-how or other intellectual property
     rights created, developed or reduced to practice by or for Supplier in (i)
     preparing any Product provided pursuant to this Agreement, or (ii) which is
     otherwise embodied within the Manufacturing Services or any other work
     provided pursuant to this Agreement, [*].

     [*] Existing Intellectual Property: means any discoveries, inventions,
     technical information, procedures, manufacturing or other processes,
     software, firmware, technology, know-how or other intellectual property
     rights owned, developed or obtained by [*] outside of this Agreement or
     known by [*] prior to the execution of this Agreement that are used by [*]
     in creating, or are embodied within, any Product, the Manufacturing
     Services or other work performed under this Agreement.

     [*] Intellectual Property: shall mean both [*] Created Intellectual
     Property and [*] Existing Intellectual Property, collectively.

     Obsolete or Surplus Materials: in the context of this Agreement shall be
     materials impacted by changes which would not otherwise be consumed in the
     [*] delivery horizon

     Product(s): in the context of this Agreement means the product(s)
     manufactured and assembled by Supplier on behalf of Sycamore under this
     Agreement as identified in Schedule 1 (or any subsequent Schedule 1
     prepared for any product to be manufactured hereunder) including any
     updates, renewals, modifications or amendments thereto.

WHEREAS, Supplier desires to enter into such a business relationship to perform
such services for Sycamore.

NOW, THEREFORE, in consideration of the mutual promises, covenants, and
Agreements contained in this Agreement, and other good and valuable
consideration, the receipt and sufficiency of which is hereby acknowledged,
Sycamore and Supplier hereby agree to the following terms and conditions for the
performance of Manufacturing Services by Supplier for Sycamore.

2.0  PURPOSE OF AGREEMENT

2.1  This Agreement is a contract for the purchase of the Recurring and
Non-Recurring Manufacturing services. Pricing shall be determined in accordance
with section 5 below.

2.2  From time to time Sycamore or its Affiliates may wish to purchase Recurring
and Non-Recurring Manufacturing Services directly from Supplier under these
terms. In such event Sycamore's Affiliate, as applicable, shall issue an
Purchase Order directly to the Supplier. The Purchase Order shall incorporate by
reference the terms and conditions of this Agreement and, with respect to that
Purchase Order, this

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the Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
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Agreement shall be interpreted as if it had been entered into directly by the
Supplier and Sycamore or Sycamore Affiliate, as applicable.

3.0  COORDINATION

3.1  Each parties' designated Coordinator to represent that party in the
implementation of this Agreement is set forth in section 23 below. Either party
may change its Coordinator by written notice to the other party.

4.0  TERM OF AGREEMENT

4.1  This Agreement shall become effective on the latter of the signature dates
of the parties, and it shall continue in effect until either party provides
written notice of termination as permitted and in accordance with Section 21 of
the Agreement.

5.0  PRICING TERMS

5.1  The prices for Recurring Manufacturing Services shall be as set forth in
Exhibit A which will be amended on a [*] basis. Prices for Non-Recurring
Manufacturing Services shall be as the parties agree in writing from time to
time. All Sycamore Purchase Orders to Supplier's facilities will be subject to
the terms of this Agreement, except and to the extent that the purchase order
varies the pricing terms hereof in accordance with section 2.1 above and pricing
such terms are accepted by Supplier. The parties agree that the pre-printed
terms and conditions on any purchase order or invoice shall be void and of no
force and effect between the parties.

     5.1.1  In cases where the Supplier provides Sycamore with Recurring
            Material Procurement Service, Sycamore and Supplier shall agree in
            writing as to the pricing terms of such service as stated in Exhibit
            A. At the time of quoting a new product for Sycamore which will
            utilize the Recurring Material Procurement Service, Supplier agrees
            to provide to Sycamore a [*] for each Sycamore assembly, based on
            [*] forecasted quantities for Sycamore's review and approval. This
            [*] is to consider the total requirements for all components or sub-
            assemblies used on other Sycamore assemblies for which the Supplier
            will be providing Recurring material procurement services. The
            pricing agreed upon by the parties shall [*] for [*] from the date
            of quotation, and shall exclude any material provided by Sycamore.
            Supplier will as soon as logistically praticable, [*] any price
            reductions to Sycamore as pricing changes on A items as identified
            in Exhibit B. Within [*] prior to the close of such [*] period, the
            Supplier shall provide an updated [*] based on the next [*]
            forecasted quantities.

5.2  All pricing based on direct labor rates for Recurring Manufacturing Service
(Assembly, Test, and Fabrication) shall be as the parties agree in writing per
Exhibit A and are based on Sycamore [*] forecast. This pricing will be reviewed
on a [*] basis and adjustments made based upon Sycamore next [*] forecast.

5.3  At [*], in the event of [*] in the [*] of [*] and/or other [*] directly [*]
to [*] for [*] for [*] shall have the right to request that [*], in good faith,
the [*] to be [*] for the [*] not [*] or [*] not [*]. Supplier shall provide and
Sycamore shall have the right to review all documentation evidencing the [*] by
the Supplier. If, after good faith negotiations, the parties are [*] to [*],
Sycamore and Supplier shall have the right to [*].

5.4  Supplier shall pay for those taxes imposed by any jurisdiction (such as
Sales Tax, if item is not for resale) where Supplier assembles, tests, inspects,
packages and/or manufactures Sycamore's goods which are directly imposed upon
the goods or services provided by Supplier to Sycamore before Sycamore takes

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the Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
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title to the goods. Sycamore shall pay for those taxes associated with the
transfer of title from Supplier to Sycamore.

5.5  Supplier agrees to follow Reasonable and Prudent Purchasing Practices in
relation to the quantities of materials and/or services placed on order with
vendors to meet the requirements of Sycamore purchase orders. Vendor's minimum
container sizes or order quantities are authorized when the value over Sycamore
purchase orders does not exceed [*]. Supplier shall receive prior written
approval from Sycamore to procure materials and/or services that exceed [*] over
materials required to meet Sycamore purchase orders.

5.6  Supplier will secure from all Vendor's, confidentiality agreements,
substantially similar to a form mutually agreed by Supplier and Sycamore.

5.7  When lead times for materials are at any time longer than the period
covered by Purchase Orders set out in Section 6.2, Supplier shall be entitled to
order such material in accordance with the forecast and such materials, lead
times, as agreed upon by the parties and as reviewed on a [*] basis. Supplier
will identify for Sycamore that material which is non-cancellable or non-
returnable. [*] will be [*] for [*] such [*] or [*] or [*]. Notwithstanding the
foregoing, Supplier will use commercially reasonable efforts to return or
consume all excess or obsolete materials.

6.0  SCHEDULING AND FORECAST

6.1  Authorization for the Supplier to ship product to Sycamore is granted only
through shipment in accordance with Sycamore's Purchase Orders. The Purchase
Order will include a description of the Services to be purchased, quantity,
routing instructions, requested delivery date , destination and price per this
Agreement. Purchase Orders shall constitute the only authorization for the
Supplier to incur any liabilities for which Supplier may be reimbursed by
Sycamore except as otherwise provided in section 5.7 of this Agreement.

6.2  Upon the execution of this Agreement, unless otherwise negotiated between
Sycamore and the Supplier, Sycamore agrees to issue Purchase Orders for a
minimum of [*] of purchases from Supplier. Thereafter, Sycamore will place
Purchase Orders with the Supplier in such a manner that will provide the
Supplier with an ongoing [*] visibility of Sycamore's scheduled delivery
requirements. Purchase Orders may be issued in writing, by mail or facsimile, or
by electronic means as the parties may from time to time agree. The supplier
will acknowledge Purchase Orders as soon as reasonably practicable and will
notify Sycamore of acceptance (or rejection, with the reasons therefor), of such
Purchase Order within [*] of receipt. Any orders which are not rejected within
[*] of receipt shall be deemed accepted. The Supplier cannot reject any Purchase
orders which conform to the terms of this Agreement. The Supplier shall be under
no obligation to accept Purchase Orders which do not conform to the terms of
this Agreement

6.3  Sycamore may request changes to shipping instructions, quantities or
delivery schedules specified in the Purchase Order releases throughout the
duration of this Agreement and Supplier shall either accept or reject such
changes within [*]. Any such changes shall be in conformance with section 6 and
section 7, unless otherwise mutually agreed upon. Sycamore shall only have [*]
covered by accepted Purchase Orders and for material purchased in accordance
with section 5.6 and 5.7 above, however, the Supplier will [*] to limit
liabilities using Reasonable and Prudent Purchasing Practices.

                                  Table 6.3.1

     Days from Notice           % quantity Rescheduling Change Allowed
          [*]                                   [*]
          [*]                                   [*]

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                   [*]                    [*]
                   [*]                    [*]

     6.3.1  The Supplier agrees to provide Sycamore with [*] to expedite
            Recurring Manufacturing Services at a rate greater than the quantity
            forecasted in the Agreement or allowed by Table 6.3.1 above. In the
            event the Supplier anticipates expediting charges, if any, these
            shall be quoted to and authorized in writing by Sycamore prior to
            Supplier's committing resources. If Sycamore [*] deliveries per [*]
            shall be governed by [*].
     6.3.2  A Delivery Date may be rescheduled only in accordance with Table
            6.3.1 contained in Appendix A (whether in whole or in part),
            provided, however, that if Sycamore's request to reschedule a
            Delivery Date is made between [*] before the originally scheduled
            delivery date, the rescheduled delivery date may be no more than [*]
            past the original delivery date. Supplier may treat any attempt to
            reschedule outside these parameters as a cancellation.
     6.3.3  If Sycamore reschedules a Delivery Date [*] or more past the
            original delivery date, Sycamore may have the option of either
            taking delivery of the product or paying Supplier an [*] of [*] per
            month, beginning on the [*] after the original delivery date. The
            [*] in this section shall apply to purchase orders placed after the
            signature date of this Agreement. At the end of the [*] from the
            original delivery date, Sycamore will pay for the finished Products.
     6.3.4  If, due to unavailability of non-commercially available or non-
            production released parts, delivery schedules are impacted [*] or
            more past the original delivery date, Sycamore and Supplier will sit
            down and mutually agree as to how Supplier shall proceed and the
            amount of [*] which shall apply. Relative to WIP, at the end of [*]
            from the original delivery date Sycamore will pay for the WIP at a
            mutually agreed to price. Sycamore will only be responsible for WIP
            that supports a [*] schedule unless agreed to in advance by both
            parties.

6.4  Sycamore agrees to provide the Supplier with a [*] rolling forecast for all
services updated on Sycamore's [*] basis. Such forecast will reflect Sycamore's
anticipated requirements for services to be procured during the next [*].
Furthermore, Sycamore and the Supplier will schedule [*] forecast reviews. These
reviews will be scheduled on the earliest mutually agreeable date for each [*].
Note: The [*] of each [*] respectively. Except as identified herein below, it is
understood and agreed by the parties that these [*] forecasts are to be used by
the Supplier for the purpose of capacity planning with no obligation and no
liability on the part of Sycamore to purchase these services except where
Purchase Orders are issued as agreed in section 6.1.

6.5  Supplier will only procure materials from Sycamore's approved vendor list.
Prior to utilizing other vendors or materials, Supplier will obtain Sycamore's
prior written consent.

7.0  CANCELLATION

7.1  If Sycamore cancels any Purchase Order, or any part thereof, within [*] of
the scheduled delivery date or any Purchase Order or any part thereof, for any
prototype, pre production or pilot Purchase Orders or one time Purchase Orders
for Product, Sycamore shall pay to Supplier the [*] so cancelled upon review of
the charges by Sycamore. Supplier will use reasonable efforts to mitigate the
costs described above.

7.2  If Sycamore cancels any Purchase Order beyond [*] of the scheduled delivery
date, or part thereof, Sycamore will pay to Supplier:

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(a)  For [*] Product at [*];

(b)  All costs of [*] and related [*] determined in accordance with Section 9 of
     this Agreement together with all amounts due pursuant to Section 6.1;

(c)  Any investment or costs associated with [*] which have [*] by Supplier [*]
     through [*] or other means and were [*] by Supplier specifically in
     relation to this Agreement with the [*] of Sycamore; and

(d)  The [*] of the [*] of the [*] that relates to [*] based on the [*]
     production process for the [*] Product orders. Such [*] shall be determined
     in accordance with [*] procedure to determine its [*].

7.3  All charges under this section shall be documented and calculated by
Supplier. Supplier shall provide to Sycamore sufficient documentation in a
reasonable format to support all charges and calculations subject to review by
Sycamore.

8.0  CHANGES

8.1  Either party may initiate change notices regarding materials or
specifications. The Coordinator of the party initiating such change notices
will document and transmit the proposed change to the other party's Coordinator,
who shall acknowledge receipt. The Recipient of a change notice will use all
reasonable efforts to provide a detailed response including increased costs
within [*] of receipt.

8.2  Both parties shall use its best effort to implement change notices as soon
as possible.

8.3  The Coordinators shall discuss any change notices and any associated impact
(schedule or financial) and shall mutually agree to any change before it may be
implemented.

8.4  Neither party will unreasonably withhold or delay agreement to a change
notice and the parties will endeavor to agree and implement, at the earliest
opportunity, change notices relating to personal and product safety or
conformance to existing specifications.

8.5  Until a change notice and any associated impact on any relevant contract
have been agreed in writing, the parties will continue to perform their
obligations under the relevant contract without taking account of the change
notice. However, if a change notice indicates that a change is required due to
safety reasons, then no further product will be manufactured without the prior
written consent of Sycamore until the parties have implemented the change
notice.

9.0  OBSOLETE MATERIAL

9.1  When material is for any reason at any time rendered Obsolete or Surplus
Materials to Sycamore requirements and that material was ordered by the Supplier
against an accepted Purchase Order, a forecast and/or pursuant to Sycamore's
written permission in accordance with section 5.6 and/or 5.7, the Supplier will:

     (a)   provide to Sycamore within [*] following the date of the event
           causing the obsolescence (the "Obsolescence Date") a notice of the
           potential cost of such obsolescence including handling charges of [*]
           for all materials with the exception of those materials defined in
           Exhibit B which will have a handling charge of [*]; and
     (b)   for a period of [*] from the Obsolescence Date, Supplier will use its
           Reasonable and Prudent Purchasing practices to mitigate Obsolete or
           Surplus Materials.

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           After such [*] period:

          (c)   Supplier shall invoice Sycamore for the agreed upon costs which
          will include [*] handling charge for all materials with the exception
          of those materials defined in Exhibit B which will have a handling
          charge of [*] and shall be paid by Sycamore in US dollars [*] from
          date of invoice.

          (d)   All charges under this section shall be documented and
          calculated by Supplier. Supplier shall provide to Sycamore sufficient
          documentation in a reasonable format to support all charges and
          calculations.

9.2  Supplier must report to Sycamore all Obsolete or Surplus Materials each
[*], or Supplier waives its right to make any claim against Sycamore for the
Obsolete or Surplus Materials in stock at the end of such quarter.

10.0 DELIVERY

10.1 Each Supplier shipment shall be accompanied by a Packing Slip which
includes as a minimum, Sycamore's part number, Purchase Order Number, the
Supplier's Part Number, serial number and quantity. Packaging of the material
shall be in accordance with Sycamore's packaging instructions and/or written
specifications. Sycamore shall be responsible for the adequacy and sufficiency
of such packaging instructions or specifications and shall hold Supplier
harmless from any costs or damages related thereto, provided Supplier completely
adheres to such instructions or specifications.

10.2 The Supplier shall deliver its services within a window of plus or minus
[*] of "Delivery Date" specified on Sycamore's Purchase Order.

10.3 Without the prior written consent of Sycamore, no partial shipments or over
shipments are allowed. Any claims for alleged shortages must be made known to
Supplier in writing within [*] of receipt at Sycamore or such claim is waived by
Sycamore.

10.4 The Supplier shall make deliveries in accordance with the schedule set
forth and mutually agreed upon in Sycamore's Purchase Order as accepted by
Supplier. Title and risk of loss and damage for items on Sycamore's purchase
orders will pass from Supplier to Sycamore upon delivery to the freight
forwarder. Supplier shall use the freight forwarder chosen by Sycamore in its
sole discretion. The Supplier shall ship all deliverables purchased under a
Purchase Order freight prepaid on Sycamore's behalf so as to be received,
allowing for normal transit times, in accordance with the schedule specified
thereon. Supplier shall invoice Sycamore for freight charges following delivery
of items on Sycamore's purchase orders.

10.5 The Supplier shall be [*] to meet the committed delivery schedule set forth
and mutually agreed upon in Sycamore's Purchase Order unless [*]. Sycamore shall
be [*] and "surface" freight unless previously approved by Sycamore in writing.

10.6 Sycamore may reject products which are reasonably established a) to have
been materially damaged by the Supplier at the delivery point or b) not to have
met, in all material respects, the relevant specification provided by Sycamore
("Rejected Products").

10.7 Sycamore will notify the Supplier in writing of Rejected Products within
[*] of original delivery and will return Rejected Products to the Supplier at
Supplier's expense within a further [*]. Supplier shall submit an RMA to
Sycamore [*] of Sycamore's notice of Rejected Products. If Sycamore does not
receive the RMA within [*], Sycamore shall nonetheless have the right to return
such Rejected Product.

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10.8  The Supplier will then at its election either repair, replace, or credit
Sycamore in respect of Rejected Products determined by Supplier not to be in
compliance with the Warranty. The cost associated with any such repair or credit
will be the responsibility of the Supplier. In the case of replacement or
credit, title of the Rejected Product shall pass to the Supplier on delivery to
the Supplier. In the event of repair, Supplier shall bear the expense of
redelivery of the repaired product.

10.9  In the event of "no fault found", as mutually agreed to by the parties,
Sycamore shall pay [*], transit of the Rejected Products, and if applicable,
repair/replacement of the products, as mutually agreed to by the parties.

10.10 In the absence of earlier notification of rejection, Sycamore will be
deemed to have accepted products [*] after delivery, provided, however, that
Sycamore's acceptance of the products shall in no way be deemed a waiver of
warranty claims.

11.0  WARRANTY

Supplier warranty

11.1  The Supplier warrants that all services will be performed in a [*] in
conformity with the [*] for such services and that the products delivered under
this Agreement will be (1) [*]; and (2) [*]. As part of the warranty provided by
SUPPLIER to Sycamore with respect to the workmanship of its Products, SUPPLIER
further warrants that all Product shall be manufactured in accordance with the
following standards:

[*]             [*]
[*]             [*]
[*]             [*]

This workmanship warranty shall apply for a period of [*] from the date the
services or products are shipped from the Supplier and may be enforced by
Sycamore (the "Warranty"). In addition, SUPPLIER shall use its commercially
reasonable best efforts to obtain from its suppliers any warranties with regard
to quality, workmanship and intellectual property rights indemnification that
are transferable to Sycamore, and SUPPLIER shall so transfer those benefits to
Sycamore so that they are enforceable by Sycamore.

11.2  Sycamore's remedy for breach of the Warranty shall be, [*]. Prior to
returning any Product that Sycamore claims to be not as warranted by SUPPLIER,
SYCAMORE shall follow Supplier's reasonable Return Material Authorization
("RMA") Procedures. SUPPLIER shall promptly provide and shall not unreasonably
withhold or delay the issuance of a RMA number. SUPPLIER shall be responsible
for all warranty expenses including the costs of incoming and outgoing shipment
for warranty repair except as noted in Section 10.9. All repairs and
replacements will be made and Product will be returned to SYCAMORE, or delivered
to destination as directed by SYCAMORE, within [*] of receipt by SUPPLIER.
Products requiring repair more than [*] shall be replaced by SUPPLIER. SUPPLIER
recognizes that as the Contract Manufacturer of SYCAMORE product that SYCAMORE
does not possess all the test equipment necessary for in-depth testing prior to
return to SUPPLIER. In any instance where SUPPLIER fails to deliver repaired or
replaced Product within [*] of receipt of defective product, then SYCAMORE shall
be entitled to [*].

However, Should Supplier fail, on a continuing basis, to meet the requirements
for repairs set forth herein after notice by SYCAMORE and Supplier's failure to
cure within a reasonable time, SYCAMORE shall have its full rights and remedies
at law or in equity for redress, subject to the limitations of damages as
otherwise set forth in this Agreement.

11.3  [*].

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11.4  The above warranties will apply in all circumstances except the following:

      (a)  Products which have been misused, modified, damaged, placed in an
      unsuitable physical or operating environment or maintained improperly or
      caused to fail by any product or service not supplied by the Supplier or
      to any Products which have been subjected to any repair not authorised in
      writing in advance by the Supplier;

      (b)  any defect caused solely by Sycamore or by an error or omission or
      design or other fault in any Sycamore Information or in any other
      drawings, documentation, data, software, information, know-how or
      Materials provided or specified by Sycamore.

      (c)  prototypes and pre-production or pilot versions of Products which
      will be warranted to conform to the specification supplied by Sycamore

      (d)  Products which, at Sycamore's specific request, did not undergo
      Supplier's standard inspection and test procedure.

      (e)  materials supplied by Sycamore

11.5  SUPPLIER will repair and/or upgrade Products which are outside the
warranty period at mutually agreed prices and terms and conditions to be
negotiated by the parties on a per product basis.

11.6  THE FORGOING WARRANTIES ARE SOLELY ENFORCEABLE BY SYCAMORE AND ARE
SUPPLIER'S SOLE OBLIGATION AND LIABILITY, AND SYCAMORE'S EXCLUSIVE REMEDIES, FOR
CLAIMS BASED ON DEFECTS IN OR FAILURE OF ANY PRODUCT OR SERVICE OR THE SUBJECT
MATTER OF ANY SERVICE AND ARE IN LIEU OF ALL OTHER WARRANTIES AND CONDITIONS
EXPRESSED OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OR CONDITIONS OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

11.7  The Supplier agrees to maintain in good working order the items contracted
for by Sycamore as Non recurring Services for the lifetime of this Agreement or
for a previously identified lifetime. The Supplier is exempted from maintaining
Non recurring Manufacturing Service items that have been obsoleted by Sycamore
or for which Sycamore mandated changes have deteriorated items beyond the scope
of general maintenance practices.

Customer Warranty

11.8  Sycamore warrants that [*] of [*] and [*] and [*] and any [*] or [*] by
[*] and [*] and [*] of [*] for the [*] to [*] and [*] the [*] and [*] to [*].

11.9  The Supplier will promptly notify Sycamore of any manufacturing problems
which it encounters and believes are related to the Product design or any
Sycamore Information or Sycamore tooling. The parties will jointly determine
whether such manufacturing problems are attributable to the Product design or
any Sycamore information or Sycamore tooling. Where such problems are so
attributable [*] be [*] for [*] by the [*] a [*] to [*] to [*]. The Supplier
will not implement any changes to the Product design or any Sycamore information
or Sycamore tooling without Sycamore's prior approval. Where any such changes
result in the delay of any scheduled delivery date for Product, the Supplier
will have no liability for such resulting delay and Sycamore may not cancel any
orders for Products affected thereby.

12.0  INDEMNIFICATION

12.1  SYCAMORE'S INDEMNIFICATION

               12.1.1  [*]

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                    12.1.2  SYCAMORE'S GENERAL INDEMNIFICATION. Sycamore agrees
                            to indemnify and hold Supplier harmless [*] from and
                            against any claims for damages, [*] that are based
                            in part or in whole on any of the following: [*]
                            Specifications, [*] or any information, [*]resulting
                            from any negligent act or omission of Sycamore. The
                            foregoing indemnity shall be contingent upon
                            Supplier: (i) giving prompt written notice to
                            Sycamore of such claim for which indemnity is
                            sought; and (ii) providing reasonable assistance to
                            Sycamore upon Sycamore's request and at Sycamore's
                            expense. [*].

          12.2 SUPPLIER'S INDEMNIFICATION

                    12.2.1  [*]

                    12.2.2  SUPPLIER'S GENERAL INDEMNIFICATION. Supplier agrees
                            to indemnify and hold Sycamore harmless [*] from and
                            against any claims for damages, [*] that are based
                            in part or in whole on [*] resulting from any
                            negligent or willful act or omission of Supplier in
                            its provision of the Non-Recurring Manufacturing
                            Services and the Recurring Manufacturing Services
                            under this Agreement. The foregoing indemnity shall
                            be contingent upon Sycamore: (i) giving prompt
                            written notice to Supplier of the third party claim
                            for which indemnification is sought; and (ii)
                            providing reasonable assistance to Supplier upon
                            Supplier's request and at Supplier's expense. [*].

          12.3 ARBITRATION. Any disputes arising under this Agreement shall be
               resolved by binding arbitration according to the procedures set
               forth in the American Arbitration Code. Such disputes will be
               heard and determined by a panel of three arbitrators. Each Party
               will appoint one arbitrator to serve on the panel. A neutral
               arbitrator will be appointed by the AAA. All arbitrators must be
               Attorneys with significant experience in resolving disputes
               involving electronic manufacturing and design services and
               optical networking equipment matters and, in the case of disputes
               arising under Sections 12.1.1 and 12.2.1, Attorneys with
               significant experience in litigation involving intellectual
               property.

13.0  PAYMENT TERMS

13.1  The Supplier shall deliver to Sycamore invoices for all goods provided and
services performed under this Agreement. Invoices will be sent to Sycamore no
earlier than the shipment of Recurring Manufacturing Services or the acceptance
of Non recurring Manufacturing Services, Payments shall be due and payable [*]
from the date of an accurate invoice containing the information set forth in
section 13.2 below. In the future the parties agree to discuss a discount for
early payment terms.

13.2  The Supplier's Invoices shall be in writing and contain the following
applicable information:

                    *  Sycamore's Purchase Order Number,
                    *  Sycamore's Part Number and Revision Level,
                    *  Quantity of Products or Services,
                    *  Unit Price of Products or Services,
                    *  Extended Price,
                    *  Shipping point
                    *  Date of Shipment
                    *  Shipping Costs

* Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
<PAGE>

All amounts due to the Supplier are payable at the Supplier designated address
or at such other place as the Supplier may hereafter designate in writing to
Sycamore.

13.3  If Sycamore becomes delinquent in payment of any material amounts due to
the Supplier without reasonable cause, the Supplier may [*] hereunder until all
the obligations to the Supplier have been brought current. The Supplier's
election to [*] shall not relieve Sycamore of any obligations hereunder.

13.4  The Supplier shall send its Invoices for goods provided and services
performed under this Agreement to Sycamore Network, Inc. Attention: Accounts
Payable, at the address specified on Sycamore's Purchase Order.

13.5  Sycamore will be solely responsible for and will pay all taxes including
value added taxes, duties or other governmental or regulatory charges in any
country resulting from the transfer of title from Supplier to Sycamore, except
for any income, corporate or other related taxes based upon Supplier's income or
property for which the Supplier is directly liable.

13.6  Supplier accepts the credit liability of any order once it is accepted and
cannot request Sycamore to pay down any credit amount after the order is
accepted.

14.0  INTELLECTUAL PROPERTY

14.1  [*] Existing Intellectual Propery. [*] shall retain all right, title and
ownership to any [*] Existing Intellectual Property that is incorporated into
any Product that is prepared as part of the Manufacturing Services or as part of
any other work provided pursuant to this Agreement or any other related
agreement executed by the Parties.

[*],  Supplier will grant to Sycamore a worldwide, non-exclusive, fully paid-up,
royalty free right and license to use, sell, and distribute the [*] as is [*]
for [*] to [*] the [*] as [*] of the [*] by [*] to this [*].

14.2  [*]. [*] shall retain all right, title and ownership to any [*] that is
incorporated into any Product that is prepared as part of the Manufacturing
Services or into any other work provided pursuant to this Agreement or any other
related agreement executed by the Parties.

[*]   will assign to [*] right, title and interest in and to the [*]. [*] hereby
[*] to [*] a [*] and [*] and [*] and the [*].

14.3  All existing intellectual property included but not limited to all
patents, applications for patents, copyrights, mask works, trade secrets and
other intellectual property rights ("Intellectual Property") owned by or
licensed to Sycamore will continue to be owned by Sycamore [*]. With respect to
any Intellectual Property [*] is in [*] and [*] of [*] to [*] the [*] to [*] for
[*] in [*] its [*] this [*].

14.4  Nothing in this Agreement or any contract grants or can be capable of
granting to Sycamore (whether directly or by implication, estoppel or otherwise)
any rights to any Intellectual Property owned by or licensed to the Supplier or
any Affiliate of the Supplier.

14.5  Without Sycamore's prior written consent, Supplier shall not disclosure of
or make other use of know-how, testing materials, Sycamore intellectual
property, the terms of this contract including prices, specifications for
products, production schedules or other performance activities under this
Agreement, which shall be subject to the confidentiality provisions of section
22 below.

15.0  CUSTOMER PROPERTY

15.1  All Sycamore information and tooling may be used by the Supplier as
required by the Supplier only for the purposes of this Agreement.

* Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
<PAGE>

15.2  All Sycamore information and all Sycamore tooling (for which, if
applicable the Supplier has been paid in full) will remain Sycamore's property
and will be treated by the Supplier with substantially the same care as it
treats its own property of a similar nature, but in no event less than a
reasonable degree of care, and will be subject to the confidentiality provisions
of section 22 below.

15.3  The costs of maintenance, calibration and repair of Sycamore tooling
supplied by Sycamore shall at all times be the responsibility of Sycamore. The
costs of maintenance, calibration and repair of Sycamore tooling that Sycamore
pays Supplier to obtain on Sycamore's behalf shall at all times be the
responsibility of Supplier.

15.4  Supplier shall (1) exercise due care in its possession of tooling and
information of Sycamore. (2) sequester and conspicuously mark Sycamore
materials, and (3) allow site inspections by Sycamore subject to receipt of
reasonable prior notice and the confidentiality obligations set forth herein.

15.5  Supplier shall carry insurance to cover the risk of loss of Sycamore's
property under its control in accordance with section 17.1.

16.0  QUALITY ASSURANCE

16.1  The Supplier will maintain quality assurance systems for the control of
material quality, processing, assembly, testing, packaging and shipping in
accordance with its usual policies and practices. The workmanship standard to be
used in building Product is IPC A-610 Rev. B Class 2, as published by the
Institute for Interconnecting and Packaging Electronic Circuits.

16.2  The Supplier will perform the test procedures relating to products and
services provided by Sycamore. If the Supplier performs tests using test
equipment, procedures and software provided by Sycamore, the Supplier will have
no liability for defects in products where failure to isolate the defect is
solely attributable to such equipment, procedures or software.

16.3  Either party may during normal business hours and following reasonable
notice and subject to the other party's normal security requirements, review the
other party's facilities and quality control procedures as reasonably necessary
for the first party to satisfy itself of the other party's compliance with its
obligations under this Agreement.

16.4  The parties will endeavor to meet [*] to discuss and resolve any issues
which may have arisen including those relating to quality, performance,
engineering changes, obsolescence or surpluses.

16.5  The parties will evaluate and mutually agree upon any additional quality
requirements going forward.

17.0  SUPPLIER'S REPRESENTATIONS AND WARRANTIES

17.1  Supplier represents and warrants that it has insurance coverage [*] in the
amounts listed below:

      General Liability:       US$[*] million

      Worker's Compensation:   As required by local law of the State in which
                               the facility is located

      Product Liability:       US$[*] million per claim and US$[*] million
                               annual aggregate

*Certain information on this page has been omitted and filed separately with
Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
<PAGE>

17.3  Supplier represents and warrants that it has the following certifications
and will keep the following certifications at Supplier's sole expense for the
duration of this Agreement:

                  ISO 9002(scheduled for September 2000) UL CSA

         Sycamore needs to provide Jabil CE marking authorization as it
               is a product level marking and product needs to be
                      tested as designed for such marking.

17.4  Supplier represents and warrants that the products and services supplied
under this Agreement and Supplier's operations are Year 2000 Compliant. Year
2000 Complaint shall mean that Supplier's operations and the products and
services supplied under this Agreement shall not be affected or interrupted by
(1) the date change from December 31, 1999 to January 1, 2000; (2) manipulating
data dated before or after 1999; (3) processing leap years.

17.5  Supplier represents and warrants that it shall maintain all finished good
or consigned materials which have been purchased by Sycamore and are on
Supplier's sites in a secure and separate location, labeled as Sycamore's
property, and free of all liens and attachments.

18.0  HAZARDOUS MATERIALS/TOXIC SUBSTANCES

18.1  Materials subject to the Toxic Substance Control Act, (15 USC 2601 et.
seq.), the Resource Conservation and Recovery Act (42 USC 6901 et. seq.) and the
Environmental Protection Agency Hazardous Waste Management Program (40 CFR 260
et. seq.) shall be SHIPPED, TRANSPORTED, DISPOSED, MARKED, LABELED, TAGGED,
PLACARDED, PACKAGED, IDENTIFIED, USED, PRESERVED, AND DOCUMENTED BY SUPPLIER AS
REQUIRED BY APPLICABLE FEDERAL REGULATIONS INCLUDING BUT NOT LIMITED TO 49 CFR
172 ET. SEQ. AND 29 CFR 1910.1200 ET. SEQ. IN ADDITION, SUPPLIER SHALL SUPPLY
THE FOLLOWING INFORMATION: DESCRIPTION OF HAZARDOUS MATERIALS AND SHIPPING NAME,
HAZARD CLASS OR DIVISION, IDENTIFICATION NUMBERS, PACKING GROUP AND LABELS PER
49 CFR 172.202 ET SEQ.

18.2  Supplier shall comply with the Hazard Communication Standard, 29 CFR
1910.1200. Supplier shall ensure that the name of the items identified on the
Material Safety Data Sheets is identical to the name which appears on the label
of the product shipped to Sycamore. Supplier shall provide a copy of the
Material Safety Data Sheet with each shipment to Sycamore.

18.3  Supplier shall comply with Section 313 of the Emergency Planning and
Community Right to Know Act of 1986 and 40 CFR Part 372, if applicable. As part
of such compliance, Supplier shall furnish its account the following information
with the initial shipment of each item to Sycamore:

            (1) A statement that the supplies contain chemicals which are
            subject to Section 313 of Title III of the Superfund
            Amendments and Reauthorization Act of 1986 and 40 CFR 372.45.
            (2) The name and associated Chemical Abstract Service Registry
            number of each chemical which has been incorporated in the
            supplies and which is listed in the specific Toxic Chemical
            Listings contained in 40 CFR 372.45.
            (3) The percentage by weight of each toxic chemical component
            of the supplies shipped.

18.4  Shipment of hazardous materials shall be by common carrier authorized to
handle the material and in accordance with 49 CFR Parts 100-109 and the "ATA
"Dangerous Goods Regulations" or "International Maritime Dangerous Goods Code"
(if applicable). This includes but is not limited to:

            .  Shipping papers must include an emergency contact number.
            .  Shipping papers and packages must show the technical names listed
               in parenthesis, the association to the basic description, and in
               the case of

<PAGE>

               mixtures, list the major hazardous components by percentage
               contributing to the hazard.
            .  Supplier shall indicate on the shipping papers whether the
               material presents Poisonous by Inhalation (PIH) hazards.
            .  At Sycamore's request, Supplier will provide test reports
               indicating Performance Oriented Packaging compliance to
               facilitate Sycamore's reshipment of Supplier's supplies.
            .  Supplier shall mark on all interior packages and shipping
               containers the closed cup flash point of flammable and
               combustible liquids.

18.5  The supplies manufactured by Supplier for Sycamore may not be manufactured
with ozone depleting substances nor may such supplies contain ozone depleting
substances unless approved by Sycamore in writing. If so approved the following
warning statement shall apply to such items: WARNING: Manufactured with
CFC-11,12,13, 111, 112, 113, 114, 115, 211, 212, 213, 214, 215, 216, 217, Halons
12211, 1301, 2402, Carbon Tetrachloride or Methyl Chloroform substances which
harm public health and environment by destroying the ozone in the upper
atmosphere.

18.6  DESCRIPTION OF HAZARDOUS MATERIAL ON SHIPPING PAPERS - The shipping
description of a hazardous material on a shipping paper must include:

            .  The proper shipping name prescribed for the material in Column 2
               of 49 CFR 172.
            .  The hazard class or division prescribed for the material as shown
               in Column 3 of 49 CFR 172 (Table) (Class names, IMO class and
               division numbers or subsidiary hazard classes may be entered in
               parentheses following the numerical hazard class).
            .  The identification number (preceded by "UN" or "NA" as
               appropriate) prescribed for the material as shown in Column 4 of
               49 CFR 172 (Table).
            .  The packing group, if any, prescribed for the material in Column
               5 of 49 CFR 172 (Table).

19.0  MINORITY/WOMEN BUSINESS ENTERPRISES

Supplier shall use its best efforts to award subcontracts to minority business
enterprises equal to [*] of its annual revenue under this Agreement consistent
with the efficient performance of this Agreement. As used in this Agreement
"minority business enterprise" means a business at least 50% of which is owned,
controlled and operated by minority group members, or in the case of publicly
owned business at least 51% of the stock of which is owned by minority group
members. A women's business enterprise means a business which is 51% owned,
controlled and operated by women. For the purpose of this definition, minority
group members are Blacks, Hispanics, Asian Pacific Islanders, American Indians
and Alaskan Natives. Supplier may rely on written representation by
subcontractors regarding their status as minority or women's business
enterprises in lieu of an independent investigation. Upon Sycamore's request,
Supplier shall provide to Sycamore a written report signed by one of its
officers which details the percentage of minority business enterprise
subcontracts comprising of the revenue generated from Sycamore's business that
quarter under this Agreement.

20.0  EXCLUSIONS AND LIMITATION OF LIABILITY

20.1  Neither party excludes or limits its liability for death or personal
injury resulting from its negligence nor liability for breach of any term
implied by statute to the extent that such liabilities cannot by law be limited
or excluded.

*Certain information on this page has been omitted and filed separately with
Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
<PAGE>

20.2  Except as set forth in sections 20.1 and 12.0 above, under no
circumstances will either party have any liability to the other party pursuant
to this Agreement, whether in contract or for negligence or otherwise and
whether related to any single event or series of connected events, for any of
the following:

          (a)  any liability in excess of:

                   (i)   in the case of damage to or loss of tangible property,
                   the value of such property; and
                   (ii)  in any event, and in respect of any other liability, an
                   amount equal [*].

          (b)  any liability for any incidental, indirect or consequential
          damages or loss of business, loss of records or data, loss of use,
          loss of profits, revenue or anticipated savings or other economic loss
          whether or not the Supplier was informed or was aware of the
          possibility of such loss.

20.3  Neither party will have liability to the other for any failure to perform
any obligation under this Agreement or any order to the extent such failure was
due to the act or omission of the other party or any agent of the other party.

21.0  TERMINATION

21.1  After notice of termination is tendered, each Coordinator shall prepare an
orderly termination of the Agreement, and for return to the owning party its
materials, equipment, records, specifications, and CONFIDENTIAL INFORMATION. The
parties agree to provide as orderly a transition toward the effective date of
termination as possible.

21.2  Either party may terminate this Agreement for any reason by providing
written notice to the other party, at least [*] in advance of the requested
termination date.

21.3  Either party may terminate this Agreement at any time for cause in the
event that any material default by the other remains uncured for more than [*]
following written notice or in the event that other party files or has filed
against it any bankruptcy, insolvency or receivership proceeding which prevents
or presents a reasonable risk of preventing such party from fulfilling is
obligations hereunder, and which is not cured [*] of written notice. ___ The
written notice shall specify the conditions constituting the default and the
corrective action, if any, which must be undertaken to cure such default. If at
the noticed date of termination the non defaulting Party in the exercise of good
faith, determines that the noticed condition of default has been cured or that
satisfactory arrangements have been undertaken to attempt the cure, then this
Agreement shall continue in force and effect.

21.4  Upon termination [*], Sycamore shall:

be responsible for:

 .     [*]
 .     [*]
 .     [*]
 .     [*]
 .     [*]
 .     [*]
 .     [*]
 .     [*]

*Certain information on this page has been omitted and filed separately with
Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
<PAGE>

All charges under this section shall be documented and calculated by Supplier.
Supplier shall provide to Sycamore sufficient documentation in a reasonable
format to support all charges and calculations.

Upon mutual agreement between the parties, Sycamore shall be entitled to set-off
against any sums due pursuant to this termination provision, any sums liquidated
or contingent which constitute sums owing or direct damages for which Supplier
would be responsible under the terms hereof.

22.0  FORCE MAJEURE

22.1  Neither party shall be liable for any delay in performance or failure to
perform obligations (other than payment obligations), in whole or in part, when
due to a labor dispute, strike, war or act of war (whether an actual declaration
is made or not), insurrection, riot, civil commotion, act of public enemy,
accident, fire, flood, or other act of God, act of any governmental authority,
judicial action, or similar causes beyond the reasonable control of such party.
If an event of Force Majeure occurs, the other party shall be immediately
notified.

22.2  If an event of Force Majeure continues for a period of [*], Sycamore shall
have the right to terminate this Agreement immediately upon written notice to
Supplier.

22.3  Interruption of scheduled deliveries to Sycamore from Supplier due to the
change in the millennium is not covered by paragraph 22.1. Supplier assumes
responsibility for insuring all of their business systems and vendors have
planned for compliance for the year 2000.

22.4  If an event of Force Majeure occurs to Supplier, Supplier will use its
commercially reasonable best efforts to put into effect an alternate plan to
continue supplying products and services to Sycamore, in order to continue
production and minimize downtime.

23.0  NOTICES

23.1  In any case where a notice or other communication is to be given or made
pursuant to any provision of this Agreement, such notice or communication will
be deemed to be received when given or made as follows:

        * If by hand delivery, on the day delivered,

        * If by telex, cable, fax, or telegraph, on the next business day
          following the date sent,

        * If by mail, on the third calendar day following posting by
          certified or registered mail, return receipt requested.

*Certain information on this page has been omitted and filed separately with
Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.
<PAGE>

23.2  All such notices mailed to Sycamore will be sent postage prepaid and
addressed to:

                  Ms. Eileen Crowley           Copy to: Mr. Steve Sabounjian
                  Sycamore Networks, Inc.
                  10 Elizabeth Drive
                  Chelmsford, MA 01824
                  FAX # (978) 256-3434

                  AND ALSO TO:
                  Sycamore Networks, Inc.
                  10 Elizabeth Drive
                  Chelmsford, MA 01824
                  Attn: Legal Dept.
                  FAX # (978) 244-1097

23.3 All such notices mailed to the Supplier will be sent postage prepaid and
addressed to:

                  Michael McGrail
                  Business Development
                  Jabil Circuit, Inc.
                  495R Billerica Avenue
                  Billerica, MA 01862
                  978-848-1074
                  FAX# 978-848-1112

                  AND ALSO TO:
                  Jabil Circuit, Inc.
                  10560 9/th/ Street North
                  St. Petersburg, FL 33716
                  Attn: General Counsel
                  FAX# (727) 803-3352

24.0  NON-ASSIGNMENT

24.1  This Agreement may not be assigned without prior written Agreement and
approval of the other party, except with regard to payment of monies, which
approval shall not be unreasonably withheld or delayed. Either party may,
however, assign this Agreement in the event of a merger or a sale of all or
substantially all of such party's assets or stock or a merger to which
assignment the both parties hereby consent.

25.0  CONFIDENTIALITY / NON-DISCLOSURE

25.1  The parties will comply with the provisions of the confidentiality
agreement between Supplier and Sycamore Networks, Inc. referenced as the
Confidentiality Agreement effective February 11, 2000. For the purposes of this
Agreement, the term "Confidential Information" shall be defined as set forth in
such Confidentiality Agreement.

25.2  No public announcement or other disclosure concerning the existence or
terms of this Agreement shall be made by either party without first obtaining
the written approval of the other party and agreement upon the nature and text
of such announcement, such approval and agreement not to be unreasonably
withheld. This Section 25 shall not apply to (i) any disclosure to a third party
which a party determines is reasonably necessary in connection with any
financing, strategic transaction, acquisition or disposition

<PAGE>

involving such party provided that the third party signs a non-disclosure
agreement with terms and conditions substantially similar to this Section 25 or
(ii) any disclosure which a party reasonably determines is required by
applicable law, regulation, regulatory authority, legal process or the rules of
any stock market on which the securities of such party are listed or quoted for
trading.

26.0  SUPERSEDING EFFECT

26.1  This Agreement, including all attachments, constitutes the entire
Agreement between the parties with respect to the subject matter hereof, and
supersedes all previous communications, representations, understandings and
Agreements, either oral or written between the parties or any official or
representative hereof. This Agreement shall be modified only by an instrument in
writing signed by duly authorized representatives of the parties.

26.2  Any standard terms and conditions set out in any Sycamore purchase order
form or any Supplier invoice or order acknowledgement will be without effect.

26.3  Any rights or obligations under this Agreement which by their nature
continue after termination will remain in effect until they are completed.

26.4  If there is any conflict or inconsistency between the terms of any
purchase order or other documents comprised in a contract and the terms of this
Agreement then the terms of this Agreement will prevail over the purchase order
or any other such document.

27.0  APPLICATION LAW

27.1  This Agreement shall be interpreted in all respects in accordance with the
laws of the Commonwealth of Massachusetts, USA exclusive of any provisions of
the United Nations Convention on the International Sale of Goods and without
regard to principles of conflict of laws. The parties submit to the
non-exclusive jurisdiction of the courts of the Commonwealth of Massachusetts.
The parties hereto expressly waive any right they may have to a jury trial and
agree that any proceedings under this Agreement shall be tried by a judge
without a jury.

28.0  GENERAL

28.1  In the manufacture and sale of product the Supplier agrees to comply with
all applicable state and federal laws and regulations, including without
limitation the requirements of the Fair Labor Standards Act of 1938 (as amended)
and to provide disclosure as to all hazardous substances utilized in the
manufacture of the product.

28.2  The parties are each independent contractors and not joint ventures,
partners, agents or representatives of the other. Neither party has any right to
create any obligation on the part of the other party. This Agreement shall not
prevent the Supplier or its Affiliates from marketing, acquiring, or developing
materials, products or services which are similar or competitive to those of
Sycamore. The Supplier may pursue activities independently with any third party,
even if similar to the activities under this Agreement.
<PAGE>

IN WITNESS WHEREOF, the parties hereto execute this Agreement to be effective on
the date referenced above.

Sycamore Networks, Inc                           Jabil Circuit, Inc.

By:____________________________                  By:___________________________
Name: John E. Dowling                            Name: Randy Haight

Title:  VP Operations                            Title: VP Business Development

Date:__________________________                  Date:_________________________
<PAGE>

                                   Exhibit A

                         Manufacturing services Pricing

The prices for recurring manufacturing services shall be mutually agreed to by
the parties by a date no later than December 15, 2000.
<PAGE>

                                  Schedule 1

                                  Product(s)

[*]

*Certain information on this page has been omitted and filed separately with
Commission. Confidential treatment has been requested with respect to the
omitted portions. Asterisks within brackets denote omissions.<PAGE>

                                 EXHIBIT 10(a)

                               AMENDMENT TO THE
                      SUPPLEMENTAL RETIREMENT PROGRAM FOR
                     MANAGEMENT PROFIT-SHARING ASSOCIATES
                         OF J. C. PENNEY COMPANY, INC.
                      ("SUPPLEMENTAL RETIREMENT PROGRAM")

         1.    The Supplemental Retirement Program is amended by deleting
Subparagraph (g) of Paragraph (7) (Special Rules for VERP Plan Participants) of
Article IV (Benefits) and reinserting it as Paragraph (8) of Article IV
(Benefits) effective as of January 1, 2001, to read as follows:

               (8)   Nonduplication of Benefits. The benefits payable to or on
                     --------------------------
         behalf of an Eligible Management Associate under the Plan shall not
         duplicate benefits payable from the Pension Plan, the VERP Plan, the
         Benefit Restoration Plan, the Mirror Savings Plans, or any separation
         pay program of the Company or a Participating Employer or a Controlled
         Group Member. To the extent that any benefits otherwise payable under
         the Plan are paid from one or more of the plans or programs described
         in the prior sentence, such benefits under the Plan shall be cancelled.

         2.    Effective as of March 22, 2001, the term "Benefit Plans Review
Committee" is deleted and the term "Human Resources and Compensation Committee"
is substituted therefor in each place in which it appears.

         3.    Also effective as of March 22, 2001, subparagraphs (a), (b), and
               (c) of Paragraph (1) of Article VIII are deleted and are replaced
               with new Subparagraphs (a), (b), and (c) to read as follows:

               (a)   in the case of an Eligible Management Associate other than
                  members of the Company's executive or senior management
                  committee (or a successor committee then in place) described
                  in Subparagraphs (b) and (c) of this Paragraph (1), the
                  Chairman of the Board or the Chief Human Resources Officer;

               (b)   in the case of an Eligible  Management Associate who is a
                  member of the Company's executive or senior management
                  committee but who is not a director of the Company, the Human
                  Resources and Compensation Committee; and

               (c)   in the case of the Chairman of the Board and an Eligible
                  Management Associate who is a member of the Company's
                  executive or senior management committee and who is also a
                  director of the Company, the Board of Directors.

         The second and third full paragraphs of Paragraph (1) of Article VIII
are amended by deleting "Benefits Administration Committee" and substituting
therefor "Chairman of the Board or the Chief Human Resources Officer."

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