<PAGE>   1
                                                                  Exhibit 10.10

                                    [PLEXUS LOGO]



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

                  COMPREHENSIVE PROFESSIONAL SERVICES AGREEMENT

This Agreement is hereby entered into on this 25th day of August, 1999 and
between Arrowpoint Communications, 235 Littleton Road, Westford, MA
018886,(hereinafter "Customer") and Plexus Corp. of 55 Jewelers Park Drive,
Neenah, WI 54956, (along with its wholly-owned subsidiaries Technology Group
Inc., and Electronic Assembly Corporation, hereafter collectively referred to as
"Plexus".)

A. PRODUCT DEVELOPMENT AND PROTOTYPE PHASE

The terms and conditions set forth in this Section A, Product Development and
Prototype Phase, as well as the terms and conditions set for in Section C,
Standard Terms and Conditions, shall be applicable to this portion of the
Agreement.

     1.  PROGRAM

         Plexus will undertake for the Customer a Program (which includes a
         Prototype Production Run) defined in the accompanying Proposal which
         this Agreement is part of. The activity described in the accompanying
         Proposal will be referred to as the "Program". Prototype Services
         further include, but not limited to, assembly labor, parts,
         manufacturing defect analysis "MDA" testing and printed circuit board
         "PCB" layout.

         a) At the Customers request, Plexus will provide a monthly detailed
            engineering report showing progress of the agreed to Program and
            schedule.

         b) From time to time, Plexus and the customer may redefine, revise,
            enlarge, amend, abandon, or undertake a new phase of activity as an
            addition to the Program. These revisions to the Program shall be
            defined in writing and agreed upon by both parties. Any additional
            cost associated with the revisions shall be quoted by Plexus and
            authorized by the Customer before work can proceed on them. Except
            for appropriate changes in objectives, schedules and budgets, all
            additional work shall be conducted under the terms of this
            Agreement.

         c) Unit cost estimates provided in this Proposal or during the course
            of the Product Development Phase are not binding and are for
            informal use only.

         d) Sections B.1."Definitions" and B. h. regarding "Engineering Changes"
            of this Agreement shall further apply to all Prototype Services
            herein.

     2.  DRAWINGS, RECORDS AND MODELS

         Customer agrees to provide to Plexus drawings, records and models,
         assembly drawings, bill of materials, approved vendor list ("AVL") and
         Gerber files. All records, sketches, original drawings, photographs,
         prototypes, assembly drawings, bill of materials, AVL, Gerber files or
         finished models and the use thereof are the exclusive property of the
         Customer. Normally any such items, which are of continuing value to the
         Customer, are returned to the Customer. In order to avoid questions
         regarding value, the customer will issue written instructions to Plexus
         within sixty (60) days following termination or completion of the
         Product Development and Prototype Phase for the disposition all such
         items. Plexus is authorized to determine the disposition of any such
         items, which are not covered by written instructions.

         At the completion of the Product Development and Prototype Phase, the
         customer will receive hard copies and/or magnetic medium of the files
         generated as a result of the Product Development and Prototype Phase.
         These deliverables are described in the Proposal. Customer will be
         responsible for maintaining the deliverables in a suitable environment.
         Plexus will assume no responsibility for archiving the deliverables at
         the completion
<PAGE>   2
         of the Product Development and Prototype Phase, unless otherwise
         negotiated or agreed upon between the parties.

     3.  COMMITMENT TO MANUFACTURE

         Customer understands that PLEXUS desires to manufacture the product at
         the end of the program. Customer understands that manufacturing of the
         product by a competitor of PLEXUS is undesirable to PLEXUS. Should
         Customer manufacture the product outside Customer's facilities,
         Customer will work with PLEXUS in good faith to ensure that PLEXUS is
         awarded the manufacture of the product. Manufacturing decisions will be
         based on competitive analysis and capability requirements.

     4.  PROTOTYPE UNITS

         Engineering and Pre-production Prototypes: During the Product
         Development and Prototype Phase, Plexus may generate several versions
         of the unit to verify design concepts. The number of prototypes and/or
         pre-production units that Plexus will deliver to the Customer is
         outlined in the body of the proposal. These prototypes may or may not
         meet the requirements of the product specification. Once these units
         are built, any modifications (hardware, software, or mechanical)
         required as a result of further testing will be done by Plexus on a
         time and material basis.

     5.  ON-GOING SUPPORT

         At the conclusion of the Product Development and Prototype Phase of the
         Program, Plexus and the Customer will jointly review the entire Program
         to assure compliance with the Program Specifications. When this has
         been completed, Plexus will notify the Customer in writing that this
         Phase has been completed, and the Customer will have thirty (30) days
         to respond by identifying errors or omissions they believe should be
         corrected by Plexus under this Agreement. After that period, the
         Customer requests for on-going support will be handled on a time and
         materials basis at Plexus' then current billing rates.

     6.  COMPENSATION, CHARGES, AND BILLING

         a) Unless other specific arrangements are agreed upon, Plexus will
            invoice the Customer each month for services rendered up to the
            total amount specified in the Proposal. Invoices are subject to
            terms of NET AMOUNT DUE IN THIRTY (30) DAYS following the date of
            the invoice.

         b) The parties agree to work in good faith on prototype unit machine
            and assembly labor rates in connection with this Agreement, which
            shall be calculated in a manner and similar to the Parts and Labor
            Pricing Estimate ("Pricing Model Estimate") set forth in Attachment
            A, attached hereto and made a part hereof. The parties further agree
            that this Pricing Model Estimate shall be used for estimating and
            budgetary purposes only and that prototype pricing may change from
            time to time due to market fluctuations, components pricing and
            other variables.

         c) Unless specifically stated to the contrary in the Proposal, the
            following parts and/or services are not included in the base
            Proposal and may be an additional billing monthly as costs are
            incurred:

            Parts, PCBs and freight which may be required for project,
            breadboard and/or prototypes, which shall be calculated in a manner
            and similar to the Parts and Labor Pricing Model Estimate ("Pricing
            Model Estimate") set forth in Attachment A, attached hereto and made
            a part hereof. The parties further agree that this Pricing Model
            shall be used for estimating and budgetary purposes only and that
            prototype pricing may change from time to time due to market
            fluctuations, components pricing and other variables.

            i.    Tooling charges for custom components such as graphics,
                  plastics, metal, etc. - actual cost plus 10%.

            ii.   Telephone, fax, and travel expenses incurred by Plexus in
                  pursuing the customers objectives and directives - actual
                  cost.

            iii.  Any travel required by Plexus in pursuing the Customer's
                  objectives and directives will be billed at the normal hourly
                  rate of the personnel performing the work for the Customer,
                  with a maximum day billing of 8 hours plus any expenses
                  incurred.

                                                                               2
<PAGE>   3
            iv.   Services of consultants or other outside personnel retained by
                  Plexus will be invoiced to the customer at a rate commensurate
                  with Plexus' in-house rates or actual cost plus 10%.

            v.    NRE and Tooling: Mark-up percentage on NRE is 10%.Plexus will
                  make reasonable efforts to minimize tooling and NRE charges
                  including competitive quoting. Customer has the right to
                  review NRE and tooling quotes. Customer has the right to
                  alternatively source NRE materials if NRE if pricing cannot be
                  mutually agreed upon between the parties.

     7.  PRODUCT DEVELOPMENT AND PROTOTYPE CANCELLATION

         During the Product Development and Prototype Phase, Customer may cancel
         this project upon providing forty-five (45) days written notice to
         Plexus. In such an event, the Customer shall be responsible for all
         expenses incurred through the effective date of cancellation,
         including, but not limited to, all labor undertaken and all materials
         purchases or ordered prior to said effective date.

     8.  ADVANCED PROCUREMENT OF COMPONENTS

         Plexus may, at its sole discretion, with Customer approval, procure in
         advance of Customer POs for assemblies, pursuant to the Prototype
         Quantity Build for each top level and board level assembly, the
         Components and/or the Long Lead Time Components, NCNR Components and/or
         Special Components, as required for each top level and board level
         assembly. Plexus shall purchase all components in accordance with
         Customer's approved vendor list (AVL) exclusively. Any deviation from
         the AVL must be authorized in writing by Customer prior to purchase by
         Plexus.

B.  MANUFACTURING PHASE

The terms and conditions set forth in this Section B, Manufacturing Phase, as
well as the terms and conditions set forth in Section C, Standard Terms and
Conditions, shall be applicable to this portion of the Agreement.

     1.  DEFINITIONS
         For the purpose of this Manufacturing Phase:

         "Long Lead Time Component(s)" shall mean all of those individual parts
         and materials whose current lead times extend beyond forty (40)
         business days. The Long Lead Time Components may, from time to time, be
         reviewed by Plexus and Customer, at the request of either party due to
         possible changes in market conditions of supply and demand affecting
         the procurement by Plexus of the Components and/or Long Lead Time
         Components for the assemblies hereunder. Any changes resulting from
         such review shall be with the mutual written agreement of Plexus and
         Customer.

         "NCNR Component(s)" shall mean those parts that are not cancelable once
         placed on order with Plexus suppliers, and are not returnable once
         delivered to Plexus. The NCNR Component(s) may, from time to time, be
         reviewed by Plexus and Customer, at the request of either party due to
         possible changes in market conditions of supply and demand affecting
         the procurement by Plexus of the Components and/or NCNR Component(s)
         for the assemblies hereunder. Any changes resulting from such review
         shall be with the mutual written agreement of Plexus and Customer.

         "Special Component(s)" shall mean those parts that have special
         procurement conditions such as limited change parameters or other
         special liability conditions that are required by Plexus' suppliers.
         The Special Component(s) may, from time to time, be reviewed by Plexus
         and Customer, at the request of either party due to possible changes in
         market conditions of supply and demand affecting the procurement by
         Plexus of the Components and/or Special Component(s) for the assemblies
         hereunder. Any changes resulting from such review shall be with the
         mutual written agreement of Plexus and Customer.

         "Monthly Rolling Quantity Forecast of Delivery Requirements" shall mean
         the written documents provided to Plexus by Customer each month
         indicating the delivery requirements projected for the next six
         (6)months.

     2.  AUTHORIZATION OF WORK/PROCUREMENT OF MATERIALS

         The following terms will apply:

                                                                               3
<PAGE>   4
         a) The purpose of this section is to define the methods under which
            Plexus will procure materials to support manufacturing of product
            for the Customer. The intent is to provide the Customer with
            flexibility to alter and/or cancel schedules within a reasonable
            period of time while at the same time minimizing Plexus liability
            that is a result of those alterations and cancellations. In order to
            offer the best possible price, Plexus does not attempt to build
            unanticipated carrying charges into its price. When changes in
            Customer requirements occur that cause Plexus to incur unanticipated
            expenses that are the result of Customer actions, the Customer is
            expected to reimburse Plexus for the costs incurred.

         b) For each top level assembly and/or board level to be manufactured,
            Plexus establishes a manufacturing lead time, which is the number of
            business days it will take, on average, to receive and kit all
            components, assemble, test and ship the lot. Unless otherwise noted,
            this manufacturing lead-time is twenty (20) business days. Plexus
            schedules all components for a particular lot of assemblies to
            arrive one manufacturing lead-time prior to the Customer due date.
            Plexus then uses this information, together with the Forecast and
            Purchase Order information as defined below, to place commitments to
            its suppliers for materials.

         c) At the beginning of each month, Customer will provide a six (6)
            month rolling Forecast of total requirements listing top level
            assembly and/or board level assembly requirements by month. This
            monthly rolling Forecast shall be used by Plexus to determine the
            Components and/or the Long Lead-Time Components, NCNR Components
            and/or Special Components that Plexus must obtain and/or procure
            and/or inventory, and unless otherwise agreed to, Plexus will
            negotiate pricing contracts with its supplier based upon the
            Forecast. Changes from the previous month's Forecast are allowed to
            the current Forecast as follows:

<TABLE>
<CAPTION>
<S>                                         <C>
            i)   Current Month:              No Change Allowed

            ii)  Second Month:               Up to 50% reduction, to be negotiated in
                                             lieu of Attachment B.

            iii) Third Month:                Up to 75% reduction, to be negotiated in
                                             lieu of Attachment B.

            iv)  Fourth Month (and beyond):  As required; increase or decrease
</TABLE>

            Changes in excess of these parameters may be mutually agreed to by
            Plexus and Customer.

            Changes to the monthly rolling Forecast may result in an excess
            inventory position (due to component market conditions), the impact
            for which is not considered in the original cost of the assembly. In
            addition, Plexus may have to place orders for quantities of
            components in excess of that required to support Customer
            requirements. This may be as a result of minimum order size
            requirements or standard package sizes from the supplier. In the
            event that the monthly rolling forecast does not define component
            consumption of sufficient magnitude to eliminate the excess
            inventory within sixty (60) business days, Plexus will notify
            Customer of its excess inventory position of Components and/or Long
            Lead Time Components, NCNR Components and/or Special Components that
            Plexus has procured and is inventorying and/or has on order with its
            suppliers. Upon receipt of such notification, Customer will purchase
            the excess inventory at Plexus' actual cost plus the agreed upon
            quoted material markup. Payment terms are net thirty (30) days.

         d) At the end of each quarter, Customer will issue Purchase Orders
            ("POs") for top level and/or board level assemblies in accordance
            with, but not limited to, the monthly rolling Forecast of total
            requirements. These POs will cover the next quarter's total
            requirements. New pricing will actually take effect the second month
            of the new quarter and run for three (3) continuous months.

         e) Plexus shall procure in advance of Customer POs for assemblies,
            pursuant to the monthly rolling Forecast for each top level and
            board level assembly, the Components and/or the Long Lead Time
            Components, NCNR Components and/or Special Components, as required
            for each top level and board level assembly. Plexus shall purchase
            all components in accordance with Customer's approved vendor list
            (AVL) exclusively. Any deviation from the AVL must be authorized in
            writing by Customer prior to purchase by Plexus.

                                                                               4
<PAGE>   5
         f) Customer may request that Plexus purchase from Customer certain
            components that the Customer has in its inventory as a result of the
            transfer of new business to Plexus. Plexus and Customer will
            negotiate in good faith to determine pricing and title transfer of
            such inventory. In addition, open component purchase order(s) with
            Customer's suppliers may be transferred to Plexus upon mutual
            agreement.

         g) Customer will communicate a monthly Production Schedule to Plexus
            outlining the top level assembly and/or board level production
            requirements. The Production Schedule will be firmed for the current
            month fifteen (15) business days prior to the start of that month,
            will be within Forecasted quantities, and have a six (6) month
            rolling horizon. Changes to the Production Schedule are allowed as
            follows:

<TABLE>
<CAPTION>
<S>                                        <C>
            (1) Current Month:             No Change Allowed
            (2) Second Month:              Up to 50% reduction, to be negotiated
                                             in lieu of Attachment B.
                Third  Month:              Up to 75% reduction, to be negotiated
                                             in lieu of Attachment B.
            (3) Fourth Month (and beyond): As required; increase or decrease
</TABLE>

            Changes to the Production Schedule within the current month may be
            mutually agreed to by Plexus and Customer.

            i)    At any time during the current month, Customer may exercise an
                  increase or decrease in delivery requirements (Flexibility
                  Quantity). This Flexibility Quantity is limited to a maximum
                  accumulation of the Flexibility Percentage outlined in
                  Attachment B for each top level and board level assembly, for
                  the current month's production based on the average of the
                  current sixty (60) business days of the Forecast. This
                  Flexibility Quantity will be available within ten (10)
                  business days of the Customer request. Additional Flexibility
                  Quantity may be mutually agreed to by Plexus and Customer. Any
                  finished goods inventory (FGI) at the end of the current month
                  will be netted from the Forecast in accordance with the change
                  provisions of this Agreement. Unless otherwise noted, any
                  remaining FGI at the end of the quarter will be shipped to
                  Customer on the last business day of the last month of the
                  quarter.

            ii)   For Production Schedule decreases issued within the current
                  month beyond the allowable Flexibility Quantity decrease, the
                  Customer will either:

                  (1) Accept shipment of the completed assemblies within the
                      current month as originally scheduled: or

                  (2) Pay full price and accept title and risk of loss for
                      completed assemblies and any work in process materials and
                      labor

            iii)  For Production Schedule decreases issued outside the current
                  month and beyond the allowable Production Schedule decrease
                  parameters, the Customer will:

                  (1) Pay for and accept title and risk of loss for the value of
                      the components (cost plus the agreed upon quoted material
                      markup) which Plexus is unable to return or reschedule to
                      meet the new schedule requirements, and

                  (2) Pay Plexus for any additional cost from suppliers
                      resulting from the prescheduling.

            iv)   For Production Schedule increases beyond the allowable
                  Flexibility Quantity, Plexus will make its best effort to
                  obtain the components necessary to meet Customer requirements.
                  However, Plexus may be unsuccessful in obtaining all of the
                  components required to meet the Customer's increased
                  requirements. In that situation, Plexus reserves the right to
                  Customer payment of the value of all inventory in house as of
                  the delivery date that is a result of the increased
                  requirement.

         h) The term "Engineering Change(s)" (hereinafter called "EC" or "EC's")
            shall mean those mechanical, software, or electrical design and/or
            specification and requirement changes which, if made to the
            assemblies to be delivered hereunder, would affect the schedule
            performance, reliability, availability,

                                                                               5
<PAGE>   6
            serviceability, appearance, dimensions, tolerance, safety or
            purchase price of such assemblies or which would require additional
            approval test.

            Plexus may determine that Engineering Changes will affect its
            ability to maintain the delivery schedule, due to the lead time of
            newly specified parts and/or the impact of substantial rework or
            modification. Under these circumstances, Plexus reserves the right
            to define a new Production Schedule for delivery and treat this as a
            Production Schedule change, with the Customer liability as defined
            under section 2e above.

            Upon receipt, Plexus shall review Customer's proposed EC and Plexus
            shall give to Customer a written evaluation of the EC, stating
            Plexus' cost to implement the EC (including the cost to modify any
            tooling), the excess quantity of Components and/or Long Lead Time
            Components, NCNR Components and/or Special Components Plexus has
            inventoried and/or has on order with its Components and/or Long Lead
            Time Components, NCNR Components and/or Special Components suppliers
            that are excess due to the EC, and associated costs and expenses
            such Components and/or Long Lead Time Components, NCNR Components
            and/or Special Components that Customer shall be liable for and the
            cost savings, if any, resulting from the EC, and the expected effect
            on the Production Schedule, availability and/or purchase price of
            such assemblies, or which may require additional approval tests by
            Customer. Plexus will submit its written evaluation to the Customer
            within five (5) business days after receipt of the proposed EC, or
            in conjunction with Customer's stated timeframe (if possible).

         i) The Customer may provide certain components required to build
            Customer's assemblies. The Customers inability to provide parts in a
            timely manner may effect Plexus's ability to meet its delivery
            schedule and may cause Plexus to incur extraordinary expenses to
            hold Plexus purchased material and/or labor in process. Under these
            circumstances, Plexus reserves the right to define a new Production
            Schedule for delivery based upon component availability information
            from the Customer and treat this as a Production Schedule change,
            with the Customer liability as defined under section 2e above.

         j) Customer may cancel requirements defined in orders and/or forecasts
            at any time before the scheduled delivery date. Any assembly
            requirements canceled within the manufacturing lead-time of the
            scheduled delivery date will be invoiced at the full agreed to price
            for the completed assembly.

            For assembly requirements canceled outside the manufacturing lead
            time of the scheduled delivery date, Customer's liability to Plexus
            will be the value of the components in Plexus's inventory (including
            the full markup as defined in the Plexus quotation), and other
            components for which Plexus has liability but which are not in
            Plexus inventory, as well as payment for any and all in-process
            manufacturing costs and expenses, and reasonable administrative
            costs and expenses. Plexus will deliver an itemized list of these
            costs to customer. Customer agrees to pay the costs identified by
            Plexus within thirty (30) calendar days of notification of such
            costs. To help minimize the impact of cancellation charges, Plexus
            will attempt to restock components at the supplier, resell the
            components, and/or utilize the components on non-customer
            assemblies.

         k) Reporting requirements are identified in Attachment C.

         l) Cost Reduction: Cost Reductions will be agreed to quarterly. Plexus
            initiated cost reductions will be shared 50/50 for 6 months.
            Customer initiated reductions will be passed through at full value.
            Actual cut-in reduction will based upon, at minimum, inventory at
            Plexus and committed on-order Product with Plexus's supplier.

         m) Customer Property: Tooling and consigned material - Plexus has the
            responsibility to have proper security, insurance, and material
            storage.

                                                                               6
<PAGE>   7
         n) Packaging and Shipping:

            i.    Product will be shipped to the customer in a manner that meets
                  industry standard packaging requirements. Plexus is not liable
                  for design related packaging issues but is liable for products
                  improperly packaged. Plexus is responsible for the selection
                  of the shipping company unless otherwise directed.

            ii.   Distribution Services: Plexus will provide Customer with
                  "Direct Ship" Distribution Services for the specified
                  product(s) identified in Attachment E, attached hereto and
                  made a part hereof. Prior to expanding these services for
                  additional product(s), Plexus and Customer must review and
                  mutually agree upon written changes to this Agreement.

                  Upon manufacturing completion of Direct Ship product, Plexus
                  will invoice Customer and identify/store product as Customer's
                  Finished Goods Inventory in a segregated location in the focus
                  factory. Consequent to the invoice transaction, Customer
                  assumes complete title, liability, and ownership of the
                  Customer's Finished Goods Inventory, which includes insurance
                  coverage and loss of product. Plexus assumes no liability for
                  Customer's Finished Goods Inventory on the premise or in
                  transit.

                  Immediately following the invoice transaction, Plexus will
                  "receive" Direct Ship product onto Customer's computer system
                  (Great Plains.) Customer to provide completely functional
                  computer terminals, with applicable hardware and software,
                  dedicated printer, and access to Customer's computer system.
                  Additionally, Customer will provide necessary training and
                  on-going computer support.

                  When Plexus receives signal to direct ship product, Plexus
                  will complete appropriate actions and transactions on
                  Customer's computer system to package, per specifications, and
                  ship product. Plexus to ship product 3rd party collect. Plexus
                  will guarantee same business day shipment of product for
                  domestic locations, if signal is received prior to 2:00 p.m.
                  CST. For signals received after 2:00 p.m. CST, Plexus will
                  make every effort to ship domestic locations the same business
                  day, but will guarantee next business day shipment. Plexus
                  will guarantee shipment of product for all international
                  locations within two (2) business days.

                  The cost to provide these Direct Ship Distribution Services
                  will be included in the unit price of each assembly shipped.
                  Payment terms and conditions shall be pursuant to this
                  Agreement.

                  Any EC's that will require re-work and/or upgrade for Customer
                  Finished Goods Inventory shall be the sole liability of the
                  Customer and follow standard re-work/upgrade policies and
                  procedures as specified in this Agreement.


         o) Testing Inspection and Acceptance: All products will be tested to
            the agreed upon process. Customer reserves the right to perform
            periodic audits or source inspection. Customer also reserves the
            right to hold product for non-conformances. The two companies must
            agree upon target test yield goals and implement a process to
            achieve those goals. Customer will pay for special pilot or
            pre-production builds. Plexus and Customer will need to agree upon a
            sample size in conducting a post pack audit. Plexus and Customer
            must also agree to the sample size for on-going reliability testing.

         p) The parties may conduct a mutual review of component pricing,
            material markup, and labor on a quarterly basis. The estimated
            quantity of Products is a factor used to determine unit pricing. In
            the


                                                                               7
<PAGE>   8
            event of a significant quantity change, either increasing or
            decreasing the estimated quantity of Products, the parties agree to
            evaluate and negotiate the impact and timing of unit price
            adjustments.

     3.  PRICING AND PAYMENT

         As full compensation for the assemblies provided by Plexus hereunder
         and its obligations contained herein, Customer will make payments
         subject to terms of NET AMOUNT DUE THIRTY (30) DAYS following the date
         of the invoice. Unless stated otherwise, prices quoted are F. O. B.
         Plexus manufacturing facility. Unless specifically stated otherwise,
         all quoted prices are firm for thirty (30) days from the date of
         quotation. Quotations are based on drawings, specifications, and other
         written information available to Plexus at the time of quotation. Any
         additional data supplied at the time of purchase may necessitate price
         adjustments. Any manufacturer's tax, retailer's occupation tax, use
         tax, sales tax, excise tax, or tax of any nature whatsoever imposed on
         or measured by the transaction between Plexus and Customer shall be
         paid by the Customer in addition to the prices quoted or invoiced. In
         the event Plexus is required to pay such tax, the Customer shall
         reimburse Plexus therefore, within ten (10) days of written demand by
         Plexus to the Customer for such reimbursement. If the transaction
         between Plexus and the Customer is exempt from all such taxes, Customer
         shall provide Plexus with a tax exemption certification or other
         document acceptable to all taxing authorities at the time the order or
         contract is submitted. The parties further agree to the credit terms
         and conditions set forth in Attachment D, attached hereto and made a
         part hereof. Plexus and Customer will review the status of deposit and
         credit history on a regular basis; and, after sufficient credit history
         is established by the Customer, Plexus will remove the credit
         restrictions set forth in Attachment D, and all business shall resume
         subject to the payment terms and provisions set forth in this Section 3
         above.

     4.  WARRANTY

         PLEXUS EXPRESSLY WARRANTS THE WORK AS SET FORTH HEREIN. PLEXUS MAKES NO
         OTHER WARRANTIES, EITHER EXPRESS OR IMPLIED (INCLUDING WITHOUT
         LIMITATION WARRANTIES AS TO MERCHANTABILITY OR FITNESS FOR PARTICULAR
         PURPOSES). IN ADDITION, THE FOLLOWING SHALL CONSTITUTE THE EXCLUSIVE
         REMEDIES FOR CUSTOMER FOR ANY BREACH BY PLEXUS OF ITS WARRANTIES
         HEREUNDER.

         Plexus warrants the assemblies against all defects in: (a) workmanship
         - where the assemblies do not conform to the agreed upon manufacturing
         specifications, for a period of fifteen (15) months from date of
         shipment, provided agreed upon testing is conducted by Plexus prior to
         shipment, except as set forth below; and (b) turnkey components - the
         warranty period provided by the component manufacturer to Plexus or
         Customer, to the extent possible or allowed by the component
         manufacturer. Plexus will not be liable for component failures beyond
         the manufacturer's warranty unless failures are determined to be caused
         by the sole negligence of Plexus and as a result of Plexus's
         manufacturing process. Plexus shall repair or replace, at Plexus's
         option and free of charge, any portion of the assemblies which is
         returned to Plexus's factory securely packaged, insured and with
         freight pre-paid within the warranty period, and which upon examination
         Plexus determines in its sole discretion to be defective in
         workmanship. Plexus will return the repaired or replaced assemblies to
         customer with freight pre-paid.

         Plexus is responsible for determining root cause of any defective
         assemblies, and will work with Customer and material supplier to
         develop corrective actions. Customer and Plexus will work cooperatively
         in pursuing corrective action if a third party is determined to cause
         failures. In the event Customer and Plexus are unable to reach an
         agreement for a resolution of a deficiency caused by a third party,
         then Plexus will recommend the final solution and/or corrective action
         plan to remedy any defect caused by such third party. Plexus will allow
         Customer to participate in any discussions with such third party as
         requested.

         This Warranty does not apply to:

         a) Design deficiencies. Plexus expressly disclaims any warranty
            responsibility for design deficiency, and for infringement for the
            like.

         b) Any modifications and/or alterations made to the Assemblies, or any
            portion thereof, without the express written authorization of Plexus
            obtained in advance. If this is the case, all warranties made herein
            are invalid and Customer shall have no further remedies hereunder
            against Plexus.

                                                                               8
<PAGE>   9
         c) Any defect, loss or damage resulting from theft, loss, fire, misuse,
            abuse, negligence, vandalism, acts of God, accident, casualty, power
            failures or surges, alteration, modification or failure to follow
            installation, operation or maintenance instructions, or any other
            cause beyond Plexus's reasonable control.

         d) Any defect, unless written notice of the defect is given by the
            Customer to Plexus as soon as practical after the defect first
            appears. The right to make a claim under this warranty expires
            fifteen (15) months from the date of shipment. Actions taken by
            Plexus to correct any defect shall not extend beyond this period.

         e) Components incorporated into the assemblies.

         IN NO EVENT, REGARDLESS OF CAUSE, SHALL PLEXUS BE LIABLE FOR
         INCIDENTAL, INDIRECT, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSSES OF
         ANY KIND, WHETHER IN CONTRACT OR IN TORT, ARISING FROM ITS PERFOMANCE
         UNDER THIS AGREEMENT.

     5.  TEST EQUIPMENT

         Unless otherwise noted, any test equipment quoted herein is warranted
         to be free from defects in material and workmanship for a period of one
         (1) year from the date of certification, provided Customer agrees that
         Plexus shall be entitled to use its own preferred Supplier for purposes
         of this section relating to test equipment and/or material.

         After the warranty period the equipment will be repaired on a time and
         materials basis. Labor will be charged at the current billing rate.
         Parts will be charged at cost plus 25%. Travel expenses will be added
         to any repairs including travel between Plexus and/or one of its
         affiliates. All dedicated test/burn in fixtures will be progress billed
         monthly up to 95% of the program cost. The remaining 5% is due upon
         fixture certification.

     6.  DOCUMENTATION

         The Customer is responsible for supplying Plexus with complete
         documentation. This includes, at a minimum, (three) 3 complete and
         current sets of documentation including, at a minimum, all prints,
         softwares, artwork, and bill of materials with manufacturer and part
         number, and any specifications, including test specializations or
         procedure, called for on any customer prints. It is the Customer's
         responsibility to assure that Plexus receives timely notification of
         any changes to the documentation, and updated prints reflecting the
         changes.

     7.  TOOLING

         All tooling produced or obtained for the assemblies delivered hereunder
         and paid for by Customer shall become and remain the property of
         Customer at the time payment in full is received for the tooling by
         Plexus. Such tooling shall be used by Plexus only for the benefit of
         Customer, and shall be delivered to Customer upon request. If Customer
         requests the return of any tooling from Plexus and Plexus determines
         the return of such tooling prevents Plexus from providing the
         assemblies to Customer, then Plexus shall inform Customer in writing,
         and Customer and Plexus shall negotiate a mutually acceptable
         resolution.

         Customer, at its sole discretion, may consign to Plexus, items,
         including, but not limited to, materials and/or equipment relating to
         the production and/or testing of the assemblies at Plexus's location.
         The material and/or equipment shall be utilized by Plexus only for the
         production and/or testing of the assemblies. Customer shall assist
         Plexus in installing the materials and/or equipment and shall provide
         training and maintenance instructions, if requested by Plexus or
         required by Customer. Customer shall be responsible for repairing,
         upgrading, replacing and/or maintaining the materials and/or equipment
         consigned to Plexus. However, Plexus shall provide routine maintenance.

         All tooling quoted herein is quoted at the cost to Plexus from its
         suppliers. A procurement charge of 10% will be added to all tooling
         with a cost of less than $5,000, and a 5% procurement charge added to
         all tooling with a cost of $5,000 or greater.

                                                                               9
<PAGE>   10
     8.  TERMINATION AND CANCELLATION OF MANUFACTURING PHASE

         During the Manufacturing Phase, either party shall have the right to
         terminate any or all activities under this agreement for any reason and
         at any time upon ninety (90) days prior written notice to the other
         party. Plexus agrees to immediately terminate the specified activity
         pursuant to this Agreement upon termination or cancellation. If this
         entire Agreement is terminated, all existing Customer POs shall be
         deemed to have been canceled unless otherwise specified by Customer.
         Customer agrees to reimburse Plexus for unrecovered expenses. In
         addition, Customer and Plexus shall negotiate a settlement of charges,
         if any, for reasonable and allowable expense directly incurred by
         Plexus including, but not limited to, manufacturing process ramp down
         costs and packaging and transportation costs and expenses, and the
         return to Customer of any Customer owned material(s), tools, equipment
         and/or any other related items, consistent with Section B2, above.

         If this entire agreement is terminated, then Plexus shall:

         a) Deliver to Customer all completed assemblies which conform to the
            applicable and then current specifications and requirements; and

         b) Return to Customer, at Customer's expense, all tooling, equipment,
            Components and/or Long Lead Time Components, drawings,
            specifications, documentations and supplies that are owned by
            Customer pursuant to the Agreement; and

         c) Prepare and submit to Customer an itemized document to include the
            quantity of assemblies in the production process.

         Upon such termination, all existing Customer POs shall be deemed to
         have been canceled unless otherwise specified by Customer and Customer,
         agrees to reimburses Plexus for unrecovered expenses, consistent with
         section B2, above.

C.  STANDARD TERMS AND CONDITIONS

The terms and conditions set forth in this Section C, STANDARD TERMS AND
CONDITIONS shall be applicable to both the Product Development and Prototype
Phase and the Manufacturing Phase of the Agreement.

     1.  MUTUAL COOPERATION

         Plexus represents that it will pursue the Agreement to the best of its
         ability and in the best interest of the Customer, and the Customer
         represents that it will cooperate with Plexus in reaching the
         objectives of the Agreement. Plexus and Customer will mutually agree on
         the appointment of a project manager for the duration of the Agreement.
         Plexus will require the Customer to establish one person to coordinate
         all activities through. In the event that the project manager is not
         operating in the best interest of the Customer, the Customer shall
         contact Plexus to discuss Agreement related concerns and/or complaints.

     2.  CONFIDENTIAL INFORMATION

         Plexus will use its best efforts to prevent the disclosure of any
         confidential information, unless specifically instructed otherwise in
         writing by the Customer, and excepting in such instances where Plexus
         may be compelled by law to make disclosures. The mechanisms for
         controlling and processing confidential information may be covered
         under a separate Confidential Disclosure Agreement (if required).

     3.  FORCE MAJEURE

         Plexus shall not be liable for any delay in or failure of performance
         under this agreement due to any contingency beyond Plexus's control,
         including, but not limited to, an act of God, war, insurrection, fire,
         riot, strike or labor dispute, sabotage, act of public enemy, flood,
         storm, accident, equipment failure, inability to obtain suitable or
         sufficient labor or material, laws or regulations, or any other cause
         beyond its reasonable control.


     4.  INTELLECTUAL PROPERTY RIGHTS

         All patents, copyrights, trademarks, or other rights pertaining to
         inventions, developments, or improvements made in the course of the
         work are the property of Customer. Plexus will, upon written direction
         from Customer, execute any and all papers and documents prepared or
         submitted by Customer as may be reasonably

                                                                              10
<PAGE>   11
         required to transfer or secure to Customer full title and authority
         over such rights. Plexus will be compensated by Customer for time and
         expense as incurred in this obligation at the then current billing
         rates for those of its employees necessary for these purposes.

         Customer agrees that it shall assume all responsibility for determining
         whether the assemblies to be designed and assembled infringe on any
         patent, copyright or trademark, and Customer shall indemnify and hold
         harmless Plexus from any liability, including legal costs and expenses,
         damages and attorney fees arising from any claim demand or suit,
         including a claim by Customer, based on allegations or claims that the
         assemblies or any design, patent, copyright, or trademark sought to be
         obtained or obtained by Customer as a result of this agreement
         constitutes an infringement of any patent, trademark or copyright of
         the United States or any foreign county.

         In the event any such claim or suit is asserted or instituted against
         Plexus, Plexus shall promptly notify Customer of the assertion of any
         such allegation or claim. Customer shall thereupon assume
         responsibility for and conduct the defense of each assertion or suit at
         its expense, and reasonable information and assistance for the defense
         of same shall be provided by Plexus for which Plexus will be
         compensated for time and expenses at its then current billing rate.
         Plexus shall have the right, at its expense, to be represented in the
         defense of any such assertion or suit by counsel of its own selection.

         The prices quoted do not include, unless specifically stated otherwise,
         the cost for testing and/or submittals for assembly approvals or any
         annual file maintenance fee, such as for UL, VDE, CSA or FCC. Plexus
         will assist Customer in obtaining such approvals and charge for same
         services at Plexus's current hourly billing rate.

     5.  LIABILITY AND INDEMNIFICATION

         Plexus will use its discretion to pursue the Agreement in the best
         interest of Customer. Plexus will be under no liability to Customer or
         otherwise for its choice of methods employed, the character or tests
         and experiments performed, the results obtained, nor for the use which
         shall thereafter be made by Customer of such results. IT IS UNDERSTOOD
         THAT OTHER THAN THE WARRANTY SET FORTH IN SECTION B4, NO OTHER
         GUARANTEES OR WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, ARE GIVEN BY
         PLEXUS, INCLUDING, BUT NOT LIMITED TO ANY WARRANTIES OF MERCHANTABILITY
         OR FITNESS FOR A PARTICULAR PURPOSE. PLEXUS SHALL NOT BE LIABLE FOR ANY
         INDIRECT, INCIDENTAL OR CONSENQUENTIAL DAMAGES (INCLUDING LOST PROFITS)
         SUSTAINED OR INCURRED IN CONNECTION WITH THIS AGREEMENT.

         Customer will fully indemnify and hold harmless Plexus from any and all
         liability, claims demands, costs and expense arising out of the use,
         publication, and/or marketing of the results of Plexus's efforts, the
         functioning of the assemblies or the product(s) which they are a part
         of, or any other matter resulting from Plexus's performance under this
         Agreement, whether such liability, claims or demands be in the nature
         of patent, trademark or copyright infringement, public or product
         liability, contract liability, or otherwise during or following the
         terms of this Agreement, and Customer shall, at its own expense, defend
         any and all such actions based thereon and shall pay all attorney's
         fees and cost and other expenses arising therefrom.

         Plexus will not be liable for errors, or expenses which may be incurred
         in its performance of this work which results from the engineering
         and/or design of the Assemblies, or from Plexus's reliance upon
         information, technological records, sketches, drawings, or prototypes
         furnished by Customer or Customer's design engineering firm. Customer
         will forthwith, during the term of this Agreement, notify Plexus of any
         and all information, technology changes, or other facts relevant to any
         aspect or phase of the Agreement.

     6.  YEAR 2000 ("Y2K")

         Customer shall maintain systems and procedures that ensure that all
         assemblies delivered by Plexus shall conform to purchase order
         requirements and shall not be affected by the transition from the year
         1999 to the year 2000 (Year 2000 Compliance.) Customer agrees that if
         any Special Tooling and/or Equipment is supplied by Customer, Customer
         warrants that: (i) the operation of such deliverables on or after
         January 1, 2000, without limitation to date, shall in no way be
         different from their operation prior to that date; and (ii) such
         deliverable will be able to process, store, record and present data
         containing dates in the Year 2000, and thereafter without limitation as
         to date, in the same manner as data containing dates prior to the year
         2000. Plexus assumes no

                                                                              11
<PAGE>   12
         liability for, nor will bear any additional costs relating to
         assemblies that are not Year 2000 compliant. Customer agrees to
         indemnify and hold harmless Plexus from any and all liability, claims,
         demands, costs and expenses arising from Customer's non-compliance with
         Year 2000. Customer further agrees, at its own expense, to defend any
         and all such actions based on such non-compliance and shall pay all
         attorney's fees and costs and other expenses arising therefrom
         including reimbursement to Plexus for any expenses or costs related
         thereto. Plexus shall not be liable for errors, or expenses which may
         be incurred from Plexus's reliance upon Customer's compliance with Year
         2000.

         Upon request by Plexus, Customer agrees to provide written
         certification to Plexus by completing a "Certification Notice",
         certifying: (1) the operating systems used by Customer will operate
         satisfactorily and will not be affected by the transition from the year
         1999 to the year 2000; (2) issues relating to Year 2000 compliance will
         not interrupt the flow of Products (including goods and services) from
         Plexus to Customer; (3) Plexus delivery of Products will not cause
         Plexus to bear any additional costs to facilitate operating without
         interruption and (4) Customer will meet Plexus deadline of September
         30, 1999 to be fully Year 2000 compliant.

     7.  CONSENT TO JURISDICTION AND APPLICABLE LAW

         The parties hereby irrevocably submit to the jurisdiction of the courts
         of the State of Wisconsin in any action or proceeding arising out of or
         relating to this Agreement, and the parties hereby irrevocably agree
         that all claims in respect of such action or proceeding may be
         determined by such courts. The parties hereby waive, to the fullest
         extent possible, the defense of an inconvenient forum to the
         maintenance of such action or proceeding, and the parties agree that a
         final judgement in any action or proceeding shall be conclusive and may
         be enforced in other jurisdictions by suit on the judgement or in any
         other matter provided by law.

         The parties hereby agree that this Agreement shall be governed by and
         will be construed in accordance with the laws of the State of
         Wisconsin, irrespective of the conflicts of laws provisions thereof.

     8.  NO RECRUITING

         Plexus and the Customer agree that during the term of this program and
         for twelve (12) months thereafter, it shall not solicit or recruit
         (even through professional recruiters) the employees of the other. This
         shall not preclude an employee of either Plexus or the Customer from
         independently pursuing and securing employment opportunities with the
         other on such employee's own initiative.


                                                                              12
<PAGE>   13
     9.  ENTIRE AGREEMENT

         This Agreement, along with the proposal, and Confidential Disclosure
         Agreement and/or quotation (if any) and Plexus's invoices, contains the
         entire understanding of the parities pertaining to the subject matter
         hereof, and no other agreements, oral or otherwise, shall be deemed to
         exist or to bind the parties. Notwithstanding anything to the contrary
         contained herein, the parties hereto agree that the terms and
         conditions set forth herein and in Plexus's invoices, proposal and
         Confidential Disclosure Agreement (if any), shall supersede any and all
         terms and conditions submitted by the Customer in any document,
         including but not limited to any terms and conditions contained in the
         Customer's purchase order. This agreement may not be modified or
         terminated orally, and no claimed modification, termination, or waiver
         shall be binding unless in writing and signed by both parties.

Accepted and agreed to:

CUSTOMER:                                     PLEXUS:
ARROWPOINT COMMUNICATIONS
                                              ENGINEERING AUTHORIZATION:

By:  /s/ Jeffrey K. White                     By: /s/ Michael T. Verstegen
   -----------------------                        -----------------------
                                                      Michael T. Verstegen

Title:  Vice President of Manufacturing       Title:  Executive Vice President
        -----------------------                   -----------------------

Date:  8/26/99                                Date:    9/17/99
    -----------------------                       -----------------------


                                              MANUFACTURING AUTHORIZATION:

                                              By:  /s/ Chuck Williams
                                                  -----------------------
                                                       Chuck Williams

                                              Title:  Vice President
                                                  -----------------------

                                              Date:       9/20/99
                                                  -----------------------

                                                                              13
<PAGE>   14
  Confidential Materials omitted and filed separately with the Securities and
                              Exchange Commission.
                        Asterisks denote such omission.

                                  ATTACHMENT A
                 PROTOCENTER PARTS/LABOR PRICING MODEL ESTIMATE


1.       Parts/materials-mark-up (reduced from our standard rate of 25%):

                            PROTOCENTER
                        --------------------
             CS100             [**]
                        --------------------
             CS800             [**]

2.       Labor Estimating Model for machine and assembly. Note that this Pricing
Model Estimate is for estimating purposes only and that prototype pricing could
drastically change if there are changes to components, board size, density,
complexity, layers, or unknown technologies. Set-up cost play a significant role
in prototype builds, therefore the quantity involved is also a significant
factor.

<TABLE>
<S>                                       <C>                    <C>
         ASSUMPTIONS                           LARGE BOARD            SMALL BOARD
                                          ---------------------- -----------------
         SIMILARITY                            SWITCH FAB               FENNICK
                                          ---------------------- -----------------
         DELIVERY                                5 DAYS                  5 DAYS
                                          ---------------------- -----------------
         QTY. OF BUILD                             25                      25
                                          ---------------------- -----------------
         SIZE                                    10 X 14                 6 X 8
                                          ---------------------- -----------------
         QTY. COMPONENTS                          2,200                   500
                                          ---------------------- -----------------
         QTY. UNIQUE PARTS                         160                     50
                                          ---------------------- -----------------
         QTY. NETS (APPROX.)                      5,000                  1,500
                                          ---------------------- -----------------
         QTY. BGA'S                                10                      2
                                          ---------------------- -----------------
         QTY. PRESS FITS                            1                      1
                                          ---------------------- -----------------
         QTY. SOT'S                                120                     42
                                          ---------------------- -----------------
         SMT                                   BOTH SIDES              BOTH SIDES
                                          ---------------------- -----------------
         PTH                                   SINGLE SIDE            SINGLE SIDE
                                          ---------------------- -----------------
         MDA TEST                             NOT INCLUDED            NOT INCLUDED
                                          ---------------------- -----------------
         PRICE PER BOARD
         QTY 10 UNITS                             [**]                    [**]
         QTY 25 UNITS                             [**]                    [**]
</TABLE>

<TABLE>
<CAPTION>
Lead Time Delivery      Adjustment Multipliers
----------------------- ----------------------
Lead Time               Multiplier
----------------------- ----------------------
<S>                     <C>
3 days                  1.200
----------------------- ----------------------
5 days                  1.000
----------------------- ----------------------
12 days                 0.915
or greater
----------------------- ----------------------
</TABLE>

Note: In some cases, 50 piece builds may not be possible to complete due to
production limitations.

This Pricing Model Estimate is provided herein only for the convenience of
Arrowpoint to use for estimating future prototypes. MDA Test will be quoted on a
case by case basis.

3.       MDA Takaya Testing (reduced from our standard rate of $125 per hour)
shall be $100 per hour.

<PAGE>   15
                                  ATTACHMENT B

                      FLEXIBILITY PERCENTAGES PER ASSEMBLY



TO BE DETERMINED AT A LATER DATE BY MUTUAL AGREEMENT BETWEEN THE PARTIES.

CUSTOMER:       J. K. W. 8/26/99                PLEXUS:         C. W. 9/20/99
                ----------------                                -------------
               INITIAL/DATE                                     INITIAL/DATE
<PAGE>   16
                                  ATTACHMENT C


                             REPORTING REQUIREMENTS



TO BE DETERMINED AT A LATER DATE BY MUTUAL AGREEMENT BETWEEN THE PARTIES.

CUSTOMER:         J. K. W. 8/26/99          PLEXUS:           C. W. 9/20/99
                  ----------------                            -------------
                  INITIAL/DATE                                INITIAL/DATE
<PAGE>   17
                                  ATTACHMENT D


March 3, 1999

Ms. Linda Russell
ArrowPoint Communications
235 Littleton Road
Westford, MA  01886

Dear Linda,

I just wanted to follow up on the agreements we have reached verbally regarding
the credit arrangement between Plexus Electronic Assembly Corporation and
ArrowPoint Communications.

1) ArrowPoint Communications, upon request from Electronic Assembly Corporation,
will provide to Electronic Assembly Corporation, confirmation of the available
cash balances under ArrowPoint's control. Such confirmation shall be from the
bank or investment firm in which the funds are held.

2) ArrowPoint will provide quarterly financial statements to Electronic Assembly
for review. Statements will be provided within 20 working days after the close
of each quarter. All information will be strictly confidential and for internal
use only.

3) Invoice terms will be NET 30 days from invoice date. Payment to be received
by Electronic Assembly Corporation on the 30th day.

4) An initial credit limit of $400,000 has been established for accounts
receivable. If in the course of business this initial limit is exceeded, you
will be contacted and may be required to pay some invoices before the NET 30 day
term so as to remain within the limit. Any increase in the limit will be based
upon length and status of credit history.

I thank you for your cooperation in working to establish these credit standards,
and look forward to a mutually beneficial relationship between our two
companies. If you have any questions or concerns, please feel free to contact me
direct (920) 751-3437.


Sincerely,


Paul A. Morris
Controller


Cc: Sue Herrmann, EAC
       Matt Knight, Plexus
       Bob Kronser, EAC
<PAGE>   18
                                  ATTACHMENT E


Plexus to provide Customer with Direct Ship Distribution Services for the
following product(s):

         -        CS100-LAN-01


         Other products may be added with Customer and Plexus Corp. mutual
         agreement.