Document:

<PAGE>   1
                                                                    EXHIBIT 10.3

             CONFIDENTIAL TREATMENT REQUESTED. CONFIDENTIAL PORTIONS
                OF THIS DOCUMENT HAVE BEEN REDACTED AND HAVE BEEN
                     SEPARATELY FILED WITH THE COMMISSION.

                             OEM PURCHASE AGREEMENT

                                     BETWEEN

                           PAIRGAIN TECHNOLOGIES INC.

                                       AND

                             VINA TECHNOLOGIES INC.

<PAGE>   2

                                      INDEX

<TABLE>
<CAPTION>
SECTION                    DESCRIPTION                                                       PAGE
-------                    -----------                                                       ----
<S>           <C>                                                                            <C>
   1.         Definitions.......................................................................3
   2.         Undertaking Sale of Product.......................................................5
   3.         Pairgain's Product Qualification and Acceptance Process, and
              Additional Product Integrity Testing..............................................6
   4.         Ordering and Delivery.............................................................7
   5.         Cancellation and Rescheduling of Purchase Orders..................................8
   6.         Intentionally left Blank..........................................................8
   7.         Prices and Payment................................................................8
   8.         Product and Process Changes.......................................................9
   9.         Quality Control and Rreliability Requirements,
              Supply Management and Pairgain's Inspecting Rights...............................10
   10.        Product Marking..................................................................12
   11.        Technical Assistance.............................................................13
   12.        Documentation....................................................................13
   13.        Title and Risk...................................................................15
   14.        Acceptance or Rejection..........................................................15
   15.        Warranty.........................................................................15
   16.        Repair Procedures................................................................19
   17.        Repair Services..................................................................20
   18.        Emergency Replacement Product....................................................23
   19.        Continuing Availability of Repair Services, Maintenance,
              Replacement and Repair Parts.....................................................23
   20.        Force Majeure....................................................................24
   21.        Hazardous Materials..............................................................25
   22.        Information/Non-Disclosure.......................................................25
   23.        Infringement.....................................................................27
   24.        Insurance........................................................................28
   25.        Termination and Continuing Rights................................................28
   26.        Indemnity........................................................................30
   27.        Consequential Damages............................................................30
   28.        Marketing of Product.............................................................30
   29.        Notices..........................................................................31
   30.        Intentionally Left Blank.........................................................31
   31.        Term.............................................................................31
   32.        North America Free Trade Agreement - Procedures..................................32
   33.        General..........................................................................32
</TABLE>

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<PAGE>   3

SCHEDULES

Schedule A -   Product List, Prices, Documentation and FCA Delivery Locations

Schedule B -   Specifications and Acceptance Program

Schedule C -   Repair and Replacement Rates, Emergency Replacement Product and
               FCA Repair Locations

Schedule D -   Change Notification

Schedule E -   Cancellation and Rescheduling

Schedule F -   Procedures for Orders Utilizing Electronic And Technical Data
               Interchange Transmission

Schedule G -   Technical Assistance

Schedule H -   Notices

                                       ii
<PAGE>   4

                             OEM PURCHASE AGREEMENT

This Agreement is made as of May 8, 2000 by and between PAIRGAIN TECHNOLOGIES
INC., a Delaware corporation having its principle office at 14402 Franklin
Avenue, Tustin, California 92780-7013, and VINA TECHNOLOGIES INC., a California
corporation, having its principal office at 42709 Lawrence Place, Fremont, CA
94538.

WHEREAS the Parties hereto desire to establish the terms and conditions under
which VINA may sell to PairGain and PairGain may purchase the Product from VINA;

NOW THEREFORE, the Parties agree as follows:

1.      DEFINITIONS

1.1     As used herein:

(a)     "ARO" shall mean after receipt of Purchase Order or Release.

(b)     "Accounts" shall mean all accounts presently purchasing VINA products
        through and being supported by PairGain and any new accounts in which
        PairGain and VINA mutally agree will be deemed PairGain accounts.

(c)     "CANCELLATION CHARGE" shall mean the appropriate charge, if any,
        pertaining to cancellation of Purchase Orders set forth in Schedule E,
        Part I.

(d)     "FCA DELIVERY LOCATIONS" shall mean FCA delivery locations listed in
        Schedule A, Part III. (i.e. FOB shipping point)

(e)     "FCA Repair Locations" shall mean VINA's repair locations listed in
        Schedule C.

(f)     "DELIVERY DATE" shall mean the date specified in a Purchase Order or a
        Release when Product are to be shipped from VINA's loading dock to the
        delivery location.

(g)     "DOCUMENTATION" shall mean the documentation as described in Schedule A,
        Part II.

(h)     "EDI" shall mean the electronic data interchange procedures established
        in Schedule F to this Agreement.

(i)     "FREE CARRIER" or " FCA" shall have the meaning set forth in the
        International Chamber of Commerce document, "INCOTERMS 1990".

(j)     "HARDWARE" shall mean the physical portion of the Product and all parts
        and components for incorporation into the Product.

                                       3
<PAGE>   5

(k)     "PARTY" shall mean PairGain or VINA and "PARTIES" shall mean PairGain
        and VINA.

(l)     "PRICES" shall mean the prices applicable to the Product as set forth in
        Schedule A, Part I.

(m)     "PROCESS" shall mean a set of inter-related resources and activities
        which transform inputs into outputs; resources may include personnel,
        finance, facilities, equipment, techniques and methods.

(n)     "PRODUCT" shall mean the HDSL Multiservice Integrated Access Device
        (IAD) and the T1 Multiservice Integrated Access Device, also commonly
        referred to as HDSL Integrator and T1 Integrator, comprising Hardware,
        Software and firmware components, as manufactured by VINA for PairGain,
        if applicable, in which case such Product are to be listed in Schedule
        A, as such Schedule A may be modified from time to time by agreement of
        the Parties.

(o)     "PURCHASE ORDERS" shall mean purchase orders issued and accepted
        pursuant to Section 4.1.

(p)     "RELEASE" shall mean a verbal release confirmed in writing, the document
        issued (by any means of transmission) or output of an electronic
        "paperless" process initiated by PairGain pursuant to a Blanket Purchase
        Order by which the Delivery Date for such Blanket Purchase Order or
        portion(s) thereof is requested.

(q)     "REPAIR SERVICES" shall mean in the case of Product, the repair or
        replacement of defective Product as set forth in Section 16 hereof.

(r)     "SET OF SCHEDULES" shall mean the set of schedules attached hereto in
        accordance with this Agreement.

(s)     "SOFTWARE" shall mean any set of programs in machine readable object
        code, residing in memories or diskettes or other media for application
        in or with the Product, which provides basic logic, operating
        instructions, user-related application instructions and network
        management information as well as associated Software documentation.

(t)     "SPECIFICATIONS" shall mean the technical specifications and the other
        requirements listed, described or referred to in Schedule B, Part I,
        including acceptance test specifications, which are required to be met
        by the Product and the Documentation.

(u)     "TERM" shall have the meaning ascribed to such term in Section 31 of
        this Agreement.

(v)     "$" or "DOLLARS" shall mean lawful money of the United States of
        America.

                                       4
<PAGE>   6

2.      UNDERTAKING SALE OF PRODUCT

2.1     This Agreement sets forth the terms and conditions applicable to: (i)
        the sale by VINA of Product as set forth in Schedule A, and (ii) the
        purchase by PairGain of such Product for resale by PairGain into
        accounts, either directly or indirectly.

2.2     Schedule A, by written mutual agreement of the Parties, may be amended
        from time to time to add thereto other Product offered for sale by VINA,
        and/or to incorporate therein enhancements or new features introduced in
        Product by VINA.

2.3     Nothing in this Agreement shall be interpreted or construed to limit
        either Party's right to perform or to continue to perform its own
        independent research, development, manufacturing or marketing of any
        type of Product or systems even if such research, development,
        manufacturing or marketing pertains to technology or Product similar to
        the Product. It is anticipated that each party will bear the costs of
        its own development work.

2.4     VINA will:

        (a)    Assure PairGain that all prices, terms, warranties and benefits
               granted to PairGain by VINA for the Product and improvements are
               at least as favorable as those now offered by VINA to any of its
               customers under similar terms and conditions. If, during the
               duration of this Agreement, VINA should enter into an arrangement
               under similar terms and conditions as this Agreement with any
               other customer providing greater benefits or more favorable
               prices, this Agreement shall be deemed to be amended to provide
               the same to PairGain under the same conditions.

        (b)    Assign PairGain as the non-exclusive sales agent for the term of
               this contact.

        (c)    Support the sales at the Accounts of the platform with a best
               effort level of support.

        (d)    Develop, manufacture, sell and support systems and Plugs for the
               HDSL Integrator and T1 Integrator.

        (e)    Develop, manufacture, sell and support an HDSL PLUG which is
               compatible and Interoperable with PairGain's HiGain product line
               for resale by PairGain.

2.5     PairGain will agree to introduce the VINA Product at the Accounts
        through its sales channels.

        (a)    PairGain agrees that the following performance goals must be met:

               PairGain will sell a combined total of at least ** per year.

** CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       5
<PAGE>   7

2.6     VINA intends to integrate PairGain's HDSL mini-modules into the T1
        Integrator to provide native HDSL connectivity. PairGain agrees to sell
        its HDSL mini-module (Module) to VINA at a preferential price for resale
        by VINA. The table in Schedule A, Part I, A, 3 specifies HDSL module
        preferential pricing for 2000. VINA and PairGain agree to re-negotiate
        in good faith the HDSL module pricing on a yearly basis. Pricing must be
        established by January 1 of each year.

2.7     VINA intends to incorporate these Modules into an HDSL Plug which
        PairGain will then OEM from VINA for sale to the Accounts. VINA agrees
        to allow PairGain to purchase the appropriate HDSL Plugs at a cost that
        is independent of the cost of the HDSL modules. The intent of this
        arrangement is to allow PairGain to resell the HDSL Plugs without having
        to double mark up the HDSL modules.

3.      PAIRGAIN'S PRODUCT QUALIFICATION AND ACCEPTANCE PROCESS, AND ADDITIONAL
        PRODUCT INTEGRITY TESTING

3.1     Prior to being purchased by PairGain, the Product will undergo a program
        of evaluation, qualification and acceptance by PairGain ("ACCEPTANCE
        PROGRAM") to verify their compliance with the Specifications. The
        Acceptance Program will be conducted in accordance with the provisions
        set out in Schedule B, Part II.

3.2     In order to enable PairGain to carry out the Acceptance Program, VINA
        will loan to PairGain, at no charge, a maximum of 4 units of the Product
        that are necessary to carry out the Acceptance Program specified in
        Schedule B, Part II.

3.3     PairGain's acceptance of the Product will take place upon successful
        completion by PairGain of its Acceptance Program, provided that the
        Product substantially comply with the Specifications. PairGain will
        notify VINA in writing of PairGain's acceptance of the Product within
        three (3) business days from successful completion of its Acceptance
        Program.

3.4     If, in the course of the carrying out the Acceptance Program, PairGain
        determines that the Product fails to substantially comply with the
        Specifications, PairGain will promptly notify VINA in writing of such
        failure in reasonable detail, and upon three (3) days receipt of such
        notice, VINA will investigate and promptly notify a member of the
        appropriate PairGain group of its plans, so that these may be discussed.
        In accordance with these discussions, VINA shall then, at its expense,
        take prompt and effective action to correct the notified deficiencies
        within such mutually agreed upon time-frame as will be required for the
        Product to be accepted on or before a date mutually agreed upon by VINA
        and PairGain. In such case, acceptance of the Product will take place
        upon verification by PairGain that the notified deficiencies have been
        corrected.

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<PAGE>   8

3.5     In the event that acceptance of the Product does not take place within
        the time-frame agreed by VINA and PairGain, PairGain or VINA shall be
        entitled to exercise any remedies under this Agreement at law or in
        equity.

3.6     In addition to the Acceptance Program, each mechanically different
        design shall be tested by PairGain on at least one occasion, and VINA
        agrees to provide reasonable assistance to PairGain in resolving any
        difficulties encountered during that testing, the exact form and terms
        of which assistance will be mutually agreed by the Parties.

4.      ORDERING AND DELIVERY

4.1     Purchase Orders

4.1.1   Product may be purchased, by PairGain through Purchase Orders with a
        schedule of delivery which PairGain may issue from time to time in
        accordance with this Agreement. The Parties acknowledge that such
        Purchase Orders may be transmitted by EDI as set forth in Schedule F
        hereof.

4.1.2   Purchase orders must utilize 30 day lead times. VINA agrees to make a
        best effort to deliver on purchase orders of less than 30 day lead
        times. PairGain agrees to provide, on a monthly basis, a 6 month rolling
        shipment requirement forecast. If a Purchase Order exceeds the previous
        forecast by over 25%, then VINA may ship the amount in excess of the
        forecast within 60 days.

4.1.3   The first 30 days of this forecast requirement will be a previously
        issued Purchase order.

        a) The second 30 days will be a conversion of a previous forecast to a
           purchase order. This purchase order can vary from the previous
           forecast by +25% to -100%.

        b) The following 4 months will be forecast requirements. These
           requirements can vary from the previous forecast as follows:
           61 - 90 days: +50%, -100%
           beyond 90 days: no limitations

4.1.4   VINA undertakes to accept any Purchase Orders issued hereunder by
        PairGain provided such Purchase Orders are consistent with this
        Agreement. VINA shall acknowledge receipt of each Blanket Purchase
        Order, Release or Purchase Order within three (3) business days ARO.

4.1.5   It is PairGain's intention that all Purchase Orders issued by PairGain
        to VINA shall refer to this Agreement. Notwithstanding that a Purchase
        Order issued in respect of Product does not refer to this Agreement, any
        such Purchase Order issued by PairGain during the Term shall be deemed
        to have been issued pursuant to this Agreement unless the Parties
        expressly agree in writing to the contrary.

4.1.6   A Purchase Order shall set forth a description of the following: (a)
        Product(s) including revision or release levels, (b) Price(s), (c)
        delivery location, (d) the PairGain location where the invoice shall be
        rendered for payment, (e) method of shipment including the names of
        carrier and broker, if applicable, (f) quantity, (g) Delivery Date, (h)
        special

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<PAGE>   9

        shipping and transportation instructions, if any, and (i) appropriate
        tax exemption certificates. All shipping documents shall reference the
        number of the Purchase Order issued for the Product contained in such
        shipment and any other information required to be included by PairGain.

4.2     Delivery

4.2.1   Product ordered shall be delivered by VINA FOB shipping point as set
        forth in the Purchase Order within a delivery lead time not to exceed 30
        days from PairGain's Purchase Order(s) unless a longer lead time is
        specified and communicated to VINA by facsimile. No partial shipment
        shall be made without PairGain's prior written consent.

4.2.2   VINA shall package the Product for shipment in accordance with
        PairGain's standard packing practices, which require compliance by VINA
        with the standards and specifications indicated in Schedule B, together
        with any modification requested by PairGain with respect to size and
        external markings. PairGain agrees to pay any extra costs associated
        with packaging and shipment that is not normal industry standard.

4.2.3   In the event that a delay in delivery exceeds thirty (30) days, PairGain
        may, by written notice to VINA, cancel the Purchase Order or Release
        without incurring any liability to PairGain whatsoever by reason
        thereof. In the event the delay in delivery is attributable to Force
        Majeure as described in Section 20, and such delay lasts more than
        thirty (30) days, the Parties shall make a joint effort to find a
        solution. The provisions contained in Section 5 shall not be applicable
        to Purchase Orders or Releases canceled under this Section 4.2.4.

5.      CANCELLATION AND RESCHEDULING OF PURCHASE ORDERS

5.1     PairGain may, at any time for its convenience and without cause, cancel,
        in accordance with Schedule E hereof, all or part of any Purchase Order
        placed hereunder for Product. In the event of any such cancellation,
        PairGain's sole liability to VINA in respect of all claims for such
        cancellation shall be to pay the cancellation charge, if any, described
        in Schedule E hereof.

5.2     PairGain may, at any time, for its convenience and without cause,
        reschedule, in accordance with Schedule E hereof, the Delivery Date of
        ordered Product from the date set forth on the Purchase Order.

6.      INTENTIONALLY LEFT BLANK

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<PAGE>   10

7.      PRICES AND PAYMENT

7.1     Except as specifically provided herein, all charges incurred by VINA in
        performing its obligations hereunder shall be paid by VINA and shall not
        be subject to reimbursement by PairGain.

7.2     The Prices applicable during the Term for all Purchase Orders for
        Products hereunder shall be determined in accordance with this Section
        and with Schedule A.

7.3     Prices are not inclusive of all special packaging in accordance with
        Section 4.2.3 and are listed in Schedule A.

7.4     Payment shall be due to VINA from PairGain thirty (30) days following
        the invoice date on an invoice for the Products, which Invoice shall be
        dated and delivered to PairGain no earlier than the Delivery Date of the
        Products.

7.5     Invoices for Product shipped hereunder or Services and for any other
        amounts which may be payable hereunder shall be forwarded directly to
        the address indicated on PairGain's Purchase Order.

8.      PRODUCT AND PROCESS CHANGES

8.1     VINA shall advise PairGain in writing of all proposed modifications and
        changes that affect form, fit, function or performance (herein
        "Change(s)") to the Product and/or Processes as soon as these are likely
        to be implemented and, in any event, within seven (7) calendar days of
        VINA's Engineering Change Notice (ECN). The Changes which require that a
        notice be forwarded to PairGain shall include, without limitation, any
        proposed Change to the Product in accordance with the classifications
        described in GR 209 CORE (herein "GR 209"). VINA shall comply with GR209
        except to the extent expressly set forth in this Section. The
        interpretation of GR 209 resides with PairGain subject to the provisions
        of Section 8.4.

8.2     VINA's written Change notifications shall be numbered in a single
        sequential numbering scheme and shall include the information specified
        in GR 209 including the following: a detailed list of the Product and/or
        Processes affected and associated Changes that must be implemented in
        conjunction with or prior to the notified Change, the compatibility of
        the Change with the Product and/or Processes currently deployed, a
        detailed description of the reason for the Change, the effect on the
        Product and/or Processes once the Change is implemented and the method
        of procedure. In addition, a detailed description of the Change, the
        consequences if the Change is not implemented and the planned
        implementation date of the Change shall be included in the notification.
        VINA will propose a disposition plan for PairGain's and its customers'
        stockrooms. PairGain will notify VINA of Product needed to implement the
        Change and location to which they should be shipped.

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<PAGE>   11

8.3     PairGain reserves the right to request at no cost, VINA's test data
        associated with any Product Changes. Furthermore, in the event PairGain
        determines it is necessary to verify the Change prior to acceptance,
        VINA shall supply, on loan and without charge, a mutually agreed upon
        number of production level quality Product for such verification.

8.4     If PairGain disagrees with any classification issued by VINA, VINA shall
        present evidence in writing, within a period of five (5) days from
        PairGain's request therefor, that such a classification is justified. If
        PairGain still disagrees with the justification, VINA shall negotiate in
        good faith with PairGain until a final resolution is mutually agreed
        upon by the Parties within thirty (30) days from the date of VINA's
        Change notice. In the event that sixty (60) days after the date of
        VINA's Change notice, the Parties still disagree on the Change
        classification, VINA and PairGain will work to a mutually agreeable
        solution taking into consideration PairGain's Customer requirements.

8.5     VINA shall not implement a Change such as those contemplated above
        without the prior written consent of PairGain, which consent may not be
        unreasonably withheld. Should PairGain fail to respond within a period
        of fifteen (15) working days from the date it has received a notice
        forwarded by VINA under this Section, then VINA shall have the right to
        implement such Change.

8.6     From acceptance of the Product by PairGain, VINA shall provide PairGain
        with a field baseline report which will include: part number, Current
        Revision Level, New Revision Level, Reason for Change, Parts affected by
        Change, Old and New Revision of PCB, if applicable. This report will be
        updated whenever an Engineering Change Order ("ECO") is generated by
        VINA and which affects form, fit, function or performance to the
        Specifications of the Product. VINA will use its best efforts to produce
        these updates within seven (7) working days of each ECO date.

8.7     Change notices relating to Product Changes should be sent to PairGain's
        Change Management department, Global Services Product Support
        Department, and Technical Publications Group and Change notices relating
        to Process Changes should be sent to PairGain's Quality department as
        referenced in Schedule B II.

9.      QUALITY CONTROL AND RELIABILITY REQUIREMENTS, SUPPLY MANAGEMENT AND
        PAIRGAIN'S INSPECTING RIGHTS

9.1     ISO 9001 Certification

9.1.1   VINA agrees to (a) provide evidence that VINA's quality management
        system is ISO 9001 Certified, or (b) in the event VINA's quality
        management system is not ISO 9001 Certified, VINA agrees to provide
        status of progress toward achieving certification. VINA also represents
        and warrants that on the date of execution of this Agreement, VINA's
        outsourced manufacturing vendor(s) had received ISO 9002 certification
        and will

                                       10
<PAGE>   12

        maintain such certification. VINA will allow PairGain to audit their
        internal quality procedures that shall follow the guidelines of ISO
        9001.

9.2     Quality Control and Reliability

9.2.1   All Product delivered by VINA shall comply with the Specifications,
        including mutually agreed upon quality and reliability target metrics
        set out therein, and such metrics shall include, but are not limited to,
        Mean Time Between Failure ("MTBF"), Return Rate ("RR") and Supplier
        Product Quality Level ("SPQL"). In the event PairGain proposes any
        Changes or additions to such quality and reliability target metrics,
        VINA shall not unreasonably refuse to agree or delay compliance with
        such Changes.

9.2.2   Product furnished hereunder by VINA shall be tested and inspected by
        VINA or its contract manufacturer prior to shipment in accordance with
        VINA's current testing and inspection procedures approved by PairGain in
        accordance with this Agreement. VINA agrees to perform all quality
        control functions to ensure compliance of the Product with the
        Specifications and conformance with good commercial practice. VINA
        warrants that all Product furnished hereunder shall meet all criteria
        set forth in the Specifications. Detailed inspection records are to be
        maintained by VINA.

9.3     Supply Management

9.3.1   VINA's procurement Process must cover all activities related to the
        purchase of components and materials including the selection of approved
        suppliers and the acceptance of the material used for manufacture of the
        Product. VINA or its contract manufacturer shall ensure through its
        procurement Process that only qualified components and materials from
        approved suppliers are used in the manufacture of Product at VINA's
        manufacturing facilities.

9.3.2   VINA or its contract manufacturer shall approve all suppliers and
        perform the qualification of all components and materials in accordance
        with the requirements of the Specifications which describes the tests to
        be performed and the results required to be attained for the
        qualification of components and materials.

9.3.3   VINA or its contract manufacturer shall ensure that its purchase
        agreements and purchase orders address any other additional applicable
        requirements. VINA shall also ensure that changes to purchase agreements
        and purchase orders are processed and approved in the same manner as the
        original document, including maintaining records of such changes.

9.3.4   PairGain may, from time to time, identify in a notice to VINA those
        components and materials used in the manufacture of Products which are
        subject to this Section 9.3.4. From the date of PairGain's notice to
        VINA, all components and materials so identified by PairGain, and the
        vendors of such components and materials, shall be jointly reviewed by
        PairGain and VINA to identify potential problem areas. In the event a
        supplier is

                                       11
<PAGE>   13

        found to be unacceptable to PairGain, VINA and PairGain shall work
        together to find a substitute vendor as soon as possible, without
        unnecessarily disrupting supply of the Products.

9.3.5   PairGain's audit of the Process and records for non-conforming
        components and materials may be held pending evidence of receiving
        non-conforming Product from VINA.

9.3.6   PairGain agrees to keep VINA informed as to any problems encountered
        with the Product and Process and to communicate promptly to VINA any and
        all modifications or improvements of the Product suggested by any
        customer, employee or agent, as PairGain considers appropriate.

9.4     PairGain's Inspection Rights

9.4.1   PairGain may inspect or test, at all reasonable times upon written
        notice at VINA's locations (including any subcontractors), any Product
        covered by this Agreement. VINA shall provide such facilities, labor,
        data, specifications, manuals and information as are reasonably required
        to allow PairGain to perform a full range of quality assurance
        functions. Inspection of Product may be performed in whole or in part
        prior to final assembly and/or completion of manufacturing or repair
        processes.

9.4.2   In addition to, and without restricting, PairGain's auditing and
        inspection rights described in this Section 9, PairGain shall have the
        right to visit VINA's manufacturing location(s) for the purpose of
        inspecting any of the Product and Processes, upon written notice.
        PairGain shall request inspection no more frequently than required by
        good commercial practices.

9.4.3   PairGain shall keep VINA informed of any problems encountered with the
        Product and Processes and shall communicate promptly to VINA any and all
        modifications or improvements to the Product and Processes suggested by
        any customer, employee or agent, as PairGain considers appropriate.

9.4.4   Any exercise of, or failure by PairGain to inspect Product, Processes
        and VINA's manufacturing locations as set forth in this Section 9 and
        Section 14 (Acceptance or Rejection) shall not constitute, or be
        construed in any manner as, an acceptance of the Product and Processes
        by PairGain or as relieving VINA from its obligation to furnish all
        Product in strict compliance with this Agreement, including the
        Specifications, and the applicable Blanket Purchase Order, Release or
        Purchase Order.

                                       12
<PAGE>   14

9.5     Product Requalification

9.5.1   Throughout the Term, VINA shall, at PairGain's request, provide to
        PairGain its standard engineering test results obtained upon
        requalification of the Product when Changes have been made to the
        Product to ensure that the Product continue to meet and comply with all
        the requirements of the Specifications.

9.5.2   VINA shall maintain compliance to all safety and environmental
        requirements associated to UL/CSA, GR-1089, GR-63 (NEBS) as required for
        all products covered by this agreement.

10.     PRODUCT MARKING

10.1    All Product shall be marked by VINA in accordance with the
        Specifications set forth in Schedule B.

10.2    Where applicable, containers of Product shall be marked for
        identification in accordance with the Specifications.

10.3    VINA shall add any other identification requested by PairGain at charges
        to be agreed by the Parties in writing prior to such identification
        being done by VINA.

11.     TECHNICAL ASSISTANCE

11.1    Product training shall be provided by VINA to PairGain as set forth in
        Schedule G, Part II.

11.2    In addition, VINA shall provide PairGain with Product training
        documentation and related information material as set forth in Schedule
        G, Part II.

11.3    Technical assistance with respect to Product furnished hereunder shall
        be provided by VINA for a period of ten (10) years after expire or
        termination of this Agreement. All telephone technical assistance
        rendered in connection with warranty pursuant to Section 15 shall be
        provided to PairGain at no charge. In all other cases, VINA's current
        rates applicable to technical assistance are set forth in Schedule A.
        The availability or performance of technical assistance under this
        Section 11 shall not be construed as altering or affecting VINA's other
        obligations under this Agreement including under Sections 8, 9, 15, and
        Schedule G.

11.4    VINA shall provide technical assistance as set forth in Schedule G, Part
        II in order to facilitate the providing by PairGain of technical
        assistance to its customers.

                                       13
<PAGE>   15

11.5    It shall be PairGain's responsibility to provide 'first line' technical
        assistance to its customers as described in Schedule G, Part I.

11.6    Any other technical assistance which VINA shall provide to PairGain or
        its customers shall be pursuant to reasonable written requests from
        PairGain's personnel as may be designated, from time to time. Such
        support shall be at prices set forth in Schedule A and on terms and
        conditions agreed upon by the Parties.

11.7    VINA's or PairGain's failure to provide technical assistance as required
        under this Section 11 and Schedule G shall constitute a material breach
        of the Party's obligations hereunder.

12.     DOCUMENTATION

12.1    VINA is to provide PairGain a hard copy and an electronic version of
        VINA's customer documentation. PairGain Technical Publications shall
        develop its customer Product Documentation from VINA's documentation.

12.1.1  VINA is to provide PairGain Technical Publications with a hard copy and
        an electronic version of Product Specifications, VINA Product
        Documentation (user manuals and release notes) at least eight (8) weeks
        prior to PairGain's Product release date. VINA will keep PairGain
        Technical Publications apprised of all Product changes as specified in
        section 8, "Product and Process Changes."

12.1.2  VINA shall advise PairGain Technical Publications in writing of all
        modifications and changes made to the VINA Product Documentation that
        affect form, fit, function or performance of the Product as documented
        in the Product Documentation as soon as these changes are likely to be
        implemented and, in any event, within seven (7) calendar days of VINA's
        Product Documentation being revised.

12.1.3  VINA will also provide PairGain Technical Publications with a hard copy
        and an electric version of the changed VINA Product Documentation within
        seven (7) calendar days of VINA's Product Documentation being revised.

12.1.4  VINA will provide PairGain Technical Publications with a working Product
        prototype, and will assist PairGain Technical Publications in upgrading
        said Product prototype within seven (7) calendar days of VINA Product
        revisions.

12.1.5  VINA will identify one point of contact for the PairGain Technical
        Publications department. This contact will assist PairGain Technical
        Publications in the identification of Product changes, and will provide
        a document review of the Product Documentation as developed by PairGain.

                                       14
<PAGE>   16

12.1.6  PairGain will release the final PairGain Product Documentation to an
        approved PairGain print vendor, and will notify VINA when this release
        has occurred. VINA can order directly from the approved PairGain print
        vendor all Product Documentation required to support Product shipment
        from VINA. This product documentation shall be shipped with each
        Product.

12.1.7  Should the need to develop Product Release Notes arise, VINA will advise
        PairGain of such need. Should PairGain opt to handle change to Product
        through the development of Product Release Notes as opposed to revising
        Product Documentation, VINA will provide PairGain Technical Publications
        with Product Release Notes source and reviews as defined for Product
        Documentation in sections 12.1.1 through 12.1.6.

12.2    VINA shall provide to PairGain at no cost, two copies each, in hardcopy
        and electronic form, of the non-confidential Documentation it uses for
        its customer training. Updates of the training manuals shall be provided
        in draft form 2 to 3 months before final release at the same time they
        are provided internally.

12.2.1  VINA shall provide PairGain's Training Department with software updates
        for existing Product as well as release notes on that software whenever
        they are released at no charge.

12.2.2  The PairGain Training Department shall develop customer training from
        VINA's documentation and Train-the-Trainer classes conducted by VINA.
        PairGain shall own all right, title and interest in the end-user
        documentation developed by PairGain based on documentation provide by
        VINA pursuant to this Agreement; provided, however, that VINA retains
        ownership of its pre-existing documentation.

12.3    PairGain shall have the right to copy and distribute the
        non-confidential Documentation as PairGain deems appropriate without any
        accounting or payment to VINA whatsoever.

13.     TITLE AND RISK

13.1    Title to the Product (excluding Software) and risk of loss of and damage
        to the Product will pass to PairGain upon delivery of Product by VINA
        FOB shipping point.

14.     ACCEPTANCE OR REJECTION

14.1    PairGain reserves the right to accept or reject Product ordered
        hereunder after the delivery of such Product to PairGain's facility.
        Product shall be deemed accepted by PairGain unless PairGain notifies
        VINA that such Product are rejected and provides the reasons for such
        rejection within fifteen (15) days after PairGain's receipt thereof and
        returns the Product to VINA via the RMA process described in Section 16.

                                       15
<PAGE>   17

14.2    If any Product is found to be not in conformance with this Agreement,
        including the applicable Purchase Order or Release, and/or fail to meet
        any of the acceptance criteria specified in the applicable
        Specifications, and/or in the event an excessive failure rate (as
        defined in the Specifications) is observed by PairGain with respect to
        Product contained in a lot/shipment, PairGain shall have the right,
        notwithstanding the warranty provisions contained in this Agreement and
        subject to the provisions of Sections 17.4.3 and 17.4.4., to reject the
        same and cancel the affected Purchase Order or Release, or, at its
        option, require that such Product be replaced or repaired within seven
        (7) days at VINA's risk and expense (including shipping charges). In
        order for PairGain to benefit from the remedies described hereunder, any
        notice of rejection issued by PairGain under this Section 14.2 shall
        include a reasonable description of the deficiencies and must be
        returned via VINA's RMA process as described in Section 16.

15.     WARRANTY

15.1    VINA warrants that:

        (a) Product will upon delivery be new and free and clear of all security
            interests, liens, or other encumbrances;

        (b) For a period of ** months from the Delivery Date of the Product,
            (such period being hereinafter referred to as the "PRODUCT WARRANTY
            PERIOD"), the Product forming part of the Product shall be free from
            defects in material and workmanship and shall conform to and operate
            in accordance with the Specifications;

        (c) Product will operate in the environment in which it is intended to
            be installed, without troubles, due to defects which result from the
            failure of the Product to conform to the Specifications;

        (d) with the exception of any notice which may be provided by VINA
            pursuant to Section 21, the Product furnished by VINA, as described
            in this Agreement, is safe for normal use, is non-toxic, presents no
            abnormal hazards to persons or their environment, and may be
            disposed of as normal electronic refuse without special precautions;

        (e) when used in accordance with the Specifications and Documentation,
            all Product provided pursuant to this Agreement shall (1) process
            date and time related data without causing any processing
            interruptions, abnormal termination's, or changes in performance
            characteristics, and (2) process and manipulate all date and time
            related functions correctly. Without limiting the generality of the
            foregoing, all Product shall:

**CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       16
<PAGE>   18

               (i)    correctly handle date and time related data before, during
                      and after January 1, 2000, including but not limited to
                      accepting date input, providing date output, and
                      performing ongoing operations on dates and portions of
                      dates including, but not limited to, calculating,
                      comparing and sequencing of dates (in both forward and
                      backward operations spanning century boundaries);

               (ii)   correctly handle leap year calculations (including but not
                      limited to identification of leap years, interval
                      calculations, day-in-year calculations, day-of-the-week
                      calculations, and week-of-the-year calculations);

               (iii)  correctly handle all two digit date and time related input
                      in a manner that resolves ambiguity as to century in a
                      disclosed, defined and predetermined manner; and

               (iv)   correctly store and provide output of all date and time
                      data in a manner that is unambiguous as to century.

15.2    VINA shall immediately notify PairGain of any and all date-related bugs,
        errors or deficiencies in the Product. For the purpose of problem
        resolution, any such date related bugs, errors or deficiencies shall be
        deemed to be bugs, errors or deficiencies of the highest priority level,
        and shall be resolved according to the procedures provided for such
        priority level.

15.3    Any provisions of this Agreement that tend to limit or eliminate the
        liability of VINA shall have no application with respect to the year
        2000 compliance warranties set out above in paragraph 15.1(e) and
        section 15.2.

15.4    Product warranty status is verified by the date code that shall be
        applied by VINA on the Product at the time of manufacturing, as per the
        requirements described in this Agreement.

15.5    The warranty set forth in this Section 15 shall not apply to any defect
        which has been caused by PairGain or its customers and arises from
        mishandling, misuse, neglect or improper testing or repair.

15.6    VINA shall, at its expense, during the Product Warranty Period, provide
        Repair Services in accordance with Section 17 in respect of Product
        which have failed to conform to above warranties.

15.7    All Product supplied under Section 17 pursuant to VINA's warranty
        obligations under this Section 15, shall be functionally equal or better
        than the vintage of the replaced units and must be backward compatible.

                                       17
<PAGE>   19

15.8    Product repairs or replacements and System Software corrections or
        replacements effected during the Product Warranty Period shall be
        warranted, as above provided, for the remainder of the Product Warranty
        Period or one hundred and eighty (180) days from the repair completion
        date, whichever is longer. Product repairs or replacements and System
        Software corrections or replacements effected after expiry of the
        Product Warranty Period shall be warranted, as above provided, for a
        period of one hundred and eighty (180) days from the repair completion
        date. The repair completion date shall be stenciled or otherwise
        identified on the Product in accordance with Section 16.4. Section 15.8
        does not apply to Products already installed in the field which are
        downloaded with new software remotely.

15.9    (a)    The warranties in this Section 15 shall survive inspection,
               acceptance and payment. Subject to the provisions of Sections
               17.4.3. and 17.4.4., in the event that VINA fails, in respect of
               single items of the Product, to perform its above warranty
               obligations upon PairGain's request, then in addition to any
               other right available to PairGain hereunder, at law, or in
               equity, VINA shall: (a) refund to PairGain the price of such
               Product; and (b) be entitled to the return of such Product.

        (b)    All transportation expenses arising from shipping the
               non-conforming Product and the repaired or replacement Product
               from VINA shall be paid by VINA. All transportation expenses
               arising from shipping the product to VINA shall be paid by
               PairGain.

        (c)    In addition to PairGain's rights as described above, PairGain
               reserves the right to repair or replace any defective Product or
               to correct any defective Product on its own or to arrange for
               such repair, replacement or correction by other entities.

15.10   VINA shall provide a Quarterly Unit Failure Analysis report on all field
        returned Product and a Component Failure Analysis report to PairGain's
        Repair Manager, to PairGain's Quality Manager and to PairGain's Product
        Brand Manager, within twenty (20) days of such request . Upon PairGain's
        request, VINA shall perform root cause analysis on any Product returned
        to VINA for repair, and shall provide a detailed report of such analysis
        to PairGain within twenty (20) days of such request.

15.11   THE WARRANTIES AND REMEDIES SET FORTH HEREIN CONSTITUTE THE ONLY
        WARRANTIES GIVEN BY VINA WITH RESPECT TO THE PRODUCT AND THE ONLY
        REMEDIES AVAILABLE TO PAIRGAIN IN THE EVENT SUCH WARRANTIES ARE
        BREACHED. THE SAID WARRANTIES ARE IN LIEU OF ALL OTHER WARRANTIES,
        WRITTEN OR ORAL, STATUTORY, EXPRESS OR IMPLIED, INCLUDING, WITHOUT
        LIMITATION ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
        PURPOSE.

15.12   Upon PairGain's request, VINA will meet with PairGain to discuss and
        negotiate in good faith such changes to the Parties' warranty rights and
        obligations as PairGain may propose

                                       18
<PAGE>   20

        as a result of PairGain's evaluation of its experience with respect to
        the foregoing warranties and remedies.

15.13   (a) After the warranty period has expired, and for an additional period
        of ten (10) years, VINA agrees to repair or replace, at its option, at
        reasonable prices and time schedules to be agreed upon on an annual
        basis and referenced in Schedule C, all Product with defects that affect
        all or substantially all Product, which result or could result in some
        form of personal health or safety hazard, property damage, or which are
        service affecting.

        (b) All transportation and delivery costs for Product returned pursuant
        to paragraph (a) from the original installation site to VINA shall be
        borne by PairGain, unless the repair in question relates to Product with
        defects that affect all or substantially all Product, which result or
        could result in some form of personal health or safety hazard, or in
        property damage, or which are service affecting, in which case all
        transportation and delivery costs from the original installation site,
        including insurance, shall be borne by VINA.

16.     REPAIR PROCEDURES

16.1    The repair procedures set forth in this Section shall be applicable to
        the provision of Repair Services by VINA under Sections 14 through 17
        during and after the Product Warranty Period.

16.2    Prior to returning any defective Product to VINA, PairGain will notify
        VINA of the defect and request authorization from VINA for the return of
        such Product. Upon such request, VINA shall provide PairGain with a
        Return Material Authorization ("RMA") number to be prominently displayed
        on the shipping container for the defective Product. PairGain shall then
        ship such Product to VINA, freight prepaid and the repaired or
        replacement Product shall be shipped by VINA, freight prepaid and
        properly insured. VINA shall prepare proper export documentation as per
        PairGain's instructions, evidencing PairGain's ownership of the Product
        and shall comply with the requirements set forth in Section 32.

16.3    PairGain shall furnish the following information with Product returned
        to VINA for Repair Services:

        (a)    PairGain or PairGain Company name and complete address;

        (b)    name(s) and telephone number(s) of PairGain's employee(s) or
               other designated persons to contact in case of questions about
               the Product;

        (c)    ship-to address for return of Product;

        (d)    quantities and model number of Products being delivered for
               repair;

                                       19
<PAGE>   21

        (e)    the nature of the defect or failure, if known; and

        (f)    whether or not returned Product are under warranty;

        (g)    Purchase Order number under which repairs are to be made, if
               Product is no longer under warranty.

16.4    VINA shall date stamp each repaired and returned Product with the repair
        date and type of repair "prefix" as per Bellcore GR-78 specifications
        and Specifications described in Schedule B.

16.5    VINA shall promptly provide a written notice to PairGain with the
        name(s) and telephone number(s) of the individual(s) to be contacted
        concerning any questions that may arise concerning Repair Services, and
        if required, and specify any special packing of Product which might be
        necessary to provide adequate in-transit protection from transportation
        damage.

16.6    Once Product has been repaired or replaced by VINA, VINA shall reissue
        to PairGain an invoice for such repaired or replacement Product and the
        charges applicable to the providing of Repair Services, if applicable,
        as set forth in Schedule C. VINA's invoice shall contain the following:

        (a)    a reference to PairGain's Purchase Order for these Repair
               Services;

        (b)    a detailed description of the Repair Services provided by VINA
               and the need therefor;

        (c)    quantities and model numbers of Products repaired and associated
               repair charges;

        (d)    applicable sales and excise taxes;

        (e)    total amount payable;

        (f)    address to which payment should be made. VINA shall promptly
               notify PairGain of returned Product which are found by VINA to be
               beyond repair and return such Product to PairGain. Product shall
               only be considered beyond repair after agreement of the Parties
               to that effect.

17.     REPAIR SERVICES

        This Section 17 shall be applicable to the provision of Repair Services
        by VINA during and after the Product Warranty Period.

17.1    Repair Services

                                       20
<PAGE>   22

17.1.1  Subject to Section 15, Repair Services shall be available to PairGain in
        accordance with the provisions contained in this Section and Sections 16
        and 18.

17.1.2  To order Repair Services, PairGain shall issue a Purchase Order and such
        Purchase Order shall contain the description of the requested Repair
        Services.

17.1.3  During the Product Warranty Period, Repair Services shall be provided by
        VINA at no charge to PairGain. After expiry of the Product Warranty
        Period, the charges applicable to the providing of Repair Services shall
        be as set forth in Schedule C unless otherwise set forth in this
        Section.

17.2    Like-for-Like Repair Services

        (a)    VINA shall hold at its expense a quantity of spares  ("SPARE
               BUFFER") which shall be sufficient to enable immediate
               replacement of Product by PairGain to its customers in cases of
               Product failure. In all cases, the Parties shall agree on the
               number of spares to be held by VINA at VINA, such quantity to be
               determined on the basis of the volume of Product delivered
               hereunder and the applicable MTBF rates so as to allow for
               immediate replacement of Products by PairGain to its customers in
               all cases of failure. In the event PairGain requests an immediate
               replacement using these spares, VINA will charge PairGain ** plus
               shipping costs for each replacement spare. This charge shall not
               apply to Product requiring replacement within the first 120 days
               of being shipped to PairGain's customer.

        (b)    Where defective Product is returned to VINA for Repair Services,
               VINA will draw from the Spare Buffer The returned replacement
               unit will added back to the Spares or returned to PairGain in
               exchange for the spare originally shipped.

        (c)    Product returned to VINA for Repair Services shall be shipped by
               PairGain freight and insurance prepaid per the RMA procedure in
               Section 16.

        (d)    VINA shall, within thirty (30) business days of providing the RMA
               number, replenish the Spare Buffer with Product replacements, and
               such replacements shall be functionally equal to or better than
               the vintage of the replaced Product, shall be backward
               compatible, and shall meet the minimum field baseline.

        (e)    VINA shall track the defective Product and provide PairGain a
               report of defects found upon repair of the Product.)

**CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       21
<PAGE>   23

17.3    Same-for-Same Repair Services

        (a)    Product returned to VINA for Repair Services shall be shipped by
               PairGain freight and insurance prepaid per the RMA process in
               Section 16.

        (b)    VINA shall track any defective Product by its unique serial
               number throughout the repair process.

        (c)    VINA shall return, after having repaired and updated the Product
               to the minimum field baseline, the exact same Product having the
               same serial number. If the serial number has to change for any
               reason, VINA shall, on the repair tag originally provided by
               PairGain, document the following information in writing: old
               serial number, new serial number and reason(s) for change.

        (d)    VINA shall provide all post repair information as required on its
               repair tag which will be attached to the PairGain repair tag and
               returned with the Product.

        (e)    VINA shall complete the same-for-same process within fifteen (15)
               working days of having received the defective Product.

17.4    Fast Cycle Failure Analysis (FCFA)

17.4.1  VINA shall perform Fast Cycle Failure Analysis ("FCFA") at no cost to
        PairGain on Product that VINA agrees has caused repeated service
        interruption in the field. PairGain will request a separate RMA number
        for each Product returned for FCFA. FCFA shall be performed by VINA in
        accordance with the following additional requirements:

        (a)    FCFA shall include a detailed root cause analysis, using
               engineering tools such as Environment Stress Screening ("ESS")
               and any other tools which may be required to determine the cause
               of the failure.

        (b)    VINA shall track any defective Product by its unique serial
               number throughout the repair process.

        (c)    VINA shall return, after having repaired and updated the Product
               to the minimum field baseline, the exact same Product having the
               same serial number. If the serial number has to change for any
               reason, VINA shall provide PairGain with the following
               information in writing: old serial number, new serial number and
               reason for change. The Product shall not be repaired without
               completion of the FCFA activity.

        (d)    VINA shall return the repaired Product with a written report
               documenting all findings as a result of the FCFA.

                                       22
<PAGE>   24

        (e)    VINA shall complete the FCFA process within seven (7) days of
               having received the defective Product (this shall be revised and
               clarified)

17.4.2  Product found defective within the first ninety (90) days of their
        initial utilization (such situation referred to as 'Dead On Arrival'
        ("DOA")), shall be returned to VINA along with the RMA documentation and
        per the RMA procedure of Section 16. Returned DOA Product shall be
        tested, at no charge to PairGain, through full functional tests and ESS
        in order to provide a root cause analysis, then repaired, re-furbished,
        upgraded to the minimum shipping baseline, restamped and returned to
        PairGain as new Product. Should the DOA occurrence represent more than
        twenty percent (20%) of the Product RR as defined in the Specifications,
        then VINA shall, in addition to performing root cause analysis,
        implement a corrective plan of action within thirty (30) days of this
        occurrence being reported. VINA will update PairGain in writing with the
        findings of the root cause analysis as well as with the corrective plan
        of action upon request by PairGain.

17.4.3  In a case of No Fault Found ("NFF") in respect of Product returned or if
        PairGain requests re-testing of Product reasonably known to PairGain as
        being in good condition, VINA shall invoice PairGain at the prices
        specified in Schedule A for their full functional tests and ESS and such
        Product shall be returned to PairGain after the tests are completed.
        Upon request, a full report of the tests and ESS shall be provided to
        PairGain. Test turnaround time for reasonable quantities shall not
        exceed ten (10) working days from the date the Product is received at
        and a Purchase Order number has been received from PairGain.

17.4.4  Should the Product failures classified by VINA as 'No Fault Found'
        ("NFF") represent more than ten percent (10%) of the Product RR as
        defined in the Specifications, then VINA and PairGain shall discuss the
        matter, and in addition to jointly performing a root cause analysis,
        shall jointly implement a corrective plan of action within thirty (30)
        days of this occurrence being reported.

17.4.5  Product repaired by VINA shall be stamped in accordance with
        requirements outlined in Bellcore's GR-78. Without limiting the
        generality of the foregoing, the stamping shall include the repair
        completion date stenciled or otherwise identified in a permanent manner
        at a readily visible location on the Hardware, unless otherwise directed
        by PairGain.

17.5    Repair Material - VINA will use new components for the repair of
        products returned under this agreement.

                                       23
<PAGE>   25

18.     EMERGENCY REPLACEMENT PRODUCT

18.1    In emergency situations threatening continuity of service or PairGain's
        end-user's in-service date, VINA shall, at PairGain's option, ship to
        PairGain or its end-users emergency replacement Product within
        twenty-four (24) hours of PairGain's request as per Section 17.2, which
        may be conveyed to VINA by telephone and/or facsimile and/or email.
        Emergency replacement Product shall be shipped via next day service and,
        for Product not under warranty, invoiced at rates then current for
        Product

19.     CONTINUING AVAILABILITY OF REPAIR SERVICES, MAINTENANCE, REPLACEMENT AND
        REPAIR PARTS

19.1    For the life of this Agreement, and for a period of ten (10) years after
        the expiry or termination of this Agreement, VINA agrees to provide
        Repair Services in respect of all Product ordered hereunder and to offer
        for sale to PairGain such functionally equivalent maintenance,
        replacement and repair parts as may be necessary for the continued
        maintenance of the Product, including discontinued Product.

19.2    VINA shall not be entitled to discontinue the offering of the Product
        unless and until a twelve (12) month prior written notice of the
        proposed discontinuance, (or such shorter period as may be reasonably
        accepted by PairGain on an individual case basis) is provided to
        PairGain. In the event of such a discontinuance, PairGain shall be
        entitled to place Purchase Orders throughout the notice period and, at
        the end of such period, a final non-cancelable Purchase Order for
        whatever quantity of the Product to be discontinued it deems
        appropriate.

19.3    VINA, upon supply discontinuance notices from its suppliers, of any sole
        source/critical components incorporated into the Products, shall notify
        PairGain immediately upon receipt of such notice. VINA shall endeavor to
        have its suppliers provide notices one (1) year in advance of
        discontinuance. VINA and PairGain will determine the quantity of such
        components to be ordered as last time buy to cover for spare
        maintenance, replacement and repair parts requirements as described in
        Section 17 (Repair Services). Furthermore, should the unavailability of
        a component require VINA to develop a replacement product, VINA will
        jointly decide with PairGain on last time buys for such component to
        ensure continuity of supply until the replacement product is approved by
        PairGain and ready to be manufactured. The provisions contained in this
        Section 19.3 shall be applicable for a period of ten (10) years after
        the expiry or termination of this Agreement.

                                       24
<PAGE>   26

20.     FORCE MAJEURE

20.1    As used herein, "FORCE MAJEURE" shall mean:

        (a)    fire, explosion, epidemic, hailstorm, tornado, cyclone,
               earthquake, flood or power failure;

        (b)    war, revolution, civil commotion, acts of public enemies,
               blockade or embargo;

        (c)    any law, order, proclamation, regulation, ordinance, demand or
               requirement of any government or any subdivision, authority, or
               representative of any such government;

        (d)    labor difficulties, including, without limitation, strikes,
               slowdowns, picketing or boycotts; or

        (e)    any other circumstances which are beyond the reasonable control
               of the Party affected, and which may include the inability to
               obtain materials, including, without limitation, any failure by
               VINA to supply as agreed any necessary components, materials,
               information or services which VINA has agreed to supply under
               this Agreement or a separate agreement.

20.2    Either Party shall be excused from any delay or failure in performance
        hereunder caused by the occurrence of any of the above Force Majeure
        events, provided however, that in the event a Force Majeure event
        continues for a period of thirty (30) days, the Parties shall make a
        joint effort to find a solution, which may include granting the other
        Party the right to terminate this Agreement upon notice to that effect
        forwarded to the other Party. The terminating Party shall have no
        liability to the terminated Party in respect of the termination of this
        Agreement in accordance with this Section 20.2.

20.3    Either Party shall make best efforts to notify the other Party in
        writing within ten (10) days after becoming aware of the occurrence of
        any Force Majeure event which may cause any delay or failure on the part
        of such Party to perform its obligations hereunder.

21.     HAZARDOUS MATERIALS

21.1    VINA shall identify and list all of the hazardous or toxic materials
        which may be contained in the Product prior to shipping the Product. For
        the purposes of this Section 21.1, the hazardous and/or toxic materials
        shall be those identified or described by characteristics in the
        regulations promulgated under all applicable laws, rules and regulations
        of any applicable governmental entity including, without limitation, the
        following: the Toxic Substances Control Act, Resource Conservation and
        Recovery Act of 1976, Hazardous Materials Transportation Act,
        Occupational Safety and Health Act of 1970, Comprehensive Environmental
        Response, Compensation and Liability Act of 1980, Consumer Product
        Safety Act, Radiation Control for Health and Safety Act of 1968,

                                       25
<PAGE>   27

        Clean Air Act, and Clean Water Act. In the event that any of the
        pertinent regulations are revised by the appropriate governmental
        authority after any Product are furnished by VINA to PairGain, VINA
        shall not be liable for retrofitting such Product in compliance with any
        such revisions.

21.2    VINA shall, at the commencement of the Term of the Agreement, review the
        pertinent regulations and the materials contained in the Product and
        provide a list of hazardous and/or toxic materials to PairGain. In
        response to particular PairGain Customer initiatives, VINA shall also
        identify such other hazardous and/or toxic substances as PairGain may
        specify.

21.3    With the exception of the condition contained in the last sentence of
        Section 21.1, VINA shall indemnify PairGain for any expenses (including
        the cost of substitute material, less accumulated depreciation) that
        PairGain may incur by reason of the recall or prohibition against
        continued use or disposal of the Product furnished by VINA, whether such
        recall or prohibition is directed by VINA, or occurs under compulsion of
        law. PairGain shall cooperate with VINA to facilitate and minimize the
        expense of any recall or prohibition against use of the Product directed
        by VINA or under compulsion of law.

21.4    With the exception of the condition contained in the last sentence of
        Section 21.1, VINA shall indemnify, defend and hold harmless PairGain
        from any claims, demands, suits, judgments, liabilities, costs and
        expenses (including, without limitation, reasonable attorneys' fees)
        which PairGain may incur under any of the laws, rules and regulations
        referred to in Section 21.1 or any amendment to said statutes by reason
        of PairGain's acquisition, use, sale or disposal of the Product
        furnished by VINA.

22.     INFORMATION/NON-DISCLOSURE

22.1    It is expected that the Parties will disclose to each other certain
        information which may be considered confidential and proprietary
        ("CONFIDENTIAL INFORMATION"), and each Party recognizes the value and
        importance of the protection of the other's Confidential Information.
        All Confidential Information owned or controlled by one Party and
        disclosed to the other Party shall remain solely the property and a
        trade secret of the disclosing Party, and its confidentiality shall be
        maintained and protected by the other Party with the same degree of care
        as it uses to protect its own confidential information of a similar
        nature, but no less than reasonable care, to prevent the unauthorized
        use, dissemination or publication of the Confidential Information.
        Except to the extent required or permitted by this Agreement, both
        Parties agree not to use, duplicate in any manner the other's
        Confidential Information or disclose it to any third party or to any of
        their employees not having a need to know for the purposes of this
        Agreement. The receiving Party's employees having a need to know the
        Confidential Information for the purpose of this Agreement may receive
        disclosure of the Confidential Information provided such employees are
        bound by confidentiality obligations no less stringent than

                                       26
<PAGE>   28
        those set forth in this Section 22. The confidentiality provisions
        contained herein shall survive the expiration or termination of this
        Agreement for a period of ten (10) years.

22.2    Confidential Information may include, but is not limited to, technical
        information, Specifications, programs and software programs. It is
        acknowledged by the Parties that a Party intended to be the recipient of
        the Confidential Information will, prior to the disclosure by the other
        Party, be afforded an opportunity to accept or to decline receiving such
        Confidential Information and the confidentiality undertakings set forth
        herein shall not apply in respect of information disclosed after a Party
        has elected not to receive such information. In order for the
        Confidential Information to be considered proprietary, confidential and
        subject to this Agreement, it shall be identified in writing at the time
        of the disclosure by an appropriate legend, marking, stamp, or positive
        written identification on the face thereof to be proprietary.
        Confidential Information which is disclosed orally shall be confirmed in
        writing by the disclosing Party within fifteen (15) days after such
        disclosure, by submitting a letter containing substantially similar
        information to the receiving Party, at such Party's address as shown in
        Schedule H hereof.

22.3    Notwithstanding the foregoing, Confidential Information shall not
        include information which:

22.3.1  now is, or hereafter becomes, available to the public from a source
        other than the disclosing Party before, or during the period of, this
        Agreement; or

22.3.2  is documented as being known by the receiving Party prior to its
        disclosure by the other Party; or

22.3.3  is independently developed by the receiving Party without recourse to
        any Confidential Information received under this Agreement and is so
        documented; or

22.3.4  is lawfully obtained by the receiving Party from a third party or
        parties without breach of confidentiality obligations; or

22.3.5  is disclosed in response to a valid order of a court or other
        governmental body or any political subdivision thereof, but only to the
        extent and for the purpose of such order and only if the receiving
        Party, to the extent possible, first notifies the disclosing Party, of
        such order and permits and reasonably assists it in seeking an
        appropriate protective order.

22.4    Nothing in this Agreement shall be interpreted or construed to limit
        either Party's right to perform or to continue to perform its own
        independent research, development, manufacturing or marketing of any
        type of product or systems even if such research, development,
        manufacturing or marketing pertains to technology or products similar to
        the Product.

                                       27
<PAGE>   29

22.5    The Parties acknowledge and agree that a breach of this Agreement may
        result in irreparable and continuing harm to the disclosing Party for
        which there may be no adequate remedy at law. In the event of a breach
        or a threatened or intended breach of this Agreement by the receiving
        Party, the receiving Party hereby consents to the granting of, and the
        disclosing Party shall be entitled to seek, preliminary injunctions
        unilaterally without notice, and final injunctions with notice,
        enjoining and restraining such breach, or threatened or intended breach,
        and to such other rights and remedies as are available at law or in
        equity to the disclosing Party except as expressly set forth herein.

23.     INFRINGEMENT

23.1    VINA shall defend PairGain against a claim that the Product infringe a
        patent, copyright or other intellectual property rights granted or
        registered in the jurisdiction which covers the geographical location of
        the original installation site if and only if (i) PairGain promptly
        notifies VINA in writing of the claim, (ii) VINA has sole control of the
        defense and all related settlement negotiations, and (iii) PairGain
        gives VINA information and assistance for the defense. VINA shall
        indemnify and hold harmless PairGain from all payments, which by final
        judgments in such suits, may be assessed against PairGain or PairGain's
        customers on account of such alleged infringement and shall pay
        resulting settlements, costs and damages finally awarded against
        PairGain and PairGain's customers by a court of law.

23.2    PairGain agrees that if the Product become, or in VINA's opinion are
        likely to become, the subject of such a claim, PairGain will permit
        VINA, at its option and expense, either to procure the right for
        PairGain to continue using such Product or to replace or modify same so
        that they become non-infringing, and, if neither of the foregoing
        alternatives is available on terms which are acceptable to VINA,
        PairGain shall have the right to return the entire unusable portion of
        such infringing or potentially infringing Product for the purchase price
        actually paid by PairGain to VINA therefor.

23.3    VINA disclaims any and all liability for any claim of patent, copyright
        or other intellectual property right infringement (i) based upon
        adherence to specifications, designs or instructions furnished by
        PairGain, (ii) any claim based upon the combination, operation or use of
        any Product supplied hereunder with Product, software or data not
        supplied by VINA in case where VINA has not been informed of such
        combination, and (iii) any claim based upon alteration of the Product
        made by any party other than VINA.

23.4    Nothing contained in this Agreement shall be deemed to grant, either
        directly or indirectly or by implication, any license under any patents
        or patent applications of VINA, except that PairGain shall have the
        normal non-exclusive, royalty-free license to use that which is implied,
        or otherwise arises by operation of law, in the sale of the Product.

                                       28
<PAGE>   30

24.     INSURANCE

24.1    VINA shall procure and maintain in full force and effect during the
        period that this Agreement is in effect with an insurance company a
        Comprehensive General Liability insurance policy with third party
        liability coverage protecting PairGain against any loss, liability or
        expense due to bodily injury, death or property damage arising out of
        this Agreement or Product delivered hereunder, to the extent such loss,
        liability or expense is not due to the negligence of PairGain. Such
        policy shall have a combined single limit of a minimum of Two Million
        Dollars ($2,000,000.00) and shall not be restricted to occurrences in
        the country of insurer of VINA.

24.2    Such policy shall be endorsed to be primary insurance and shall provide
        that it will not be canceled or altered with respect to the coverage
        specified in 24.1 without at least thirty (30) days prior written notice
        to PairGain. Not later than ten (10) days following the execution of
        this Agreement, VINA shall furnish PairGain with a certificate of such
        insurance and evidence that the premiums therefor have been paid.
        Maintenance of such insurance and the performance by VINA of its
        obligations under this Section shall not relieve VINA of liability under
        the indemnity provisions set forth in this Agreement.

25.     TERMINATION AND CONTINUING RIGHTS

25.1    The Agreement may be terminated upon notice by one Party, at its sole
        discretion in the event the other party is affected by any one of the
        following events:

        a)   the institution by one Party of insolvency, receivership or
             bankruptcy proceedings or any other material proceedings for the
             settlement of its debts, including, without limitation, a
             reorganization, a compromise, an arrangement or assignment for the
             benefit of its creditors; the institution of such proceedings
             against a Party which such Party has failed to resolve in its favor
             within twenty (20) calendar days after appropriate services of
             process; a Party making a general assignment for the benefit of
             creditors; or a Party's dissolution or ceasing to do business in
             the normal course; or

        b)   has a substantial part of its assets seized; or

        c)   assigns the Agreement or any part thereof in violation of Section
             33.2 (Assignment); the affected Party is obliged to immediately
             give notice to the other of the occurrence of any such event.

                                       29
<PAGE>   31

25.2    The Agreement and/or any Purchase Order or Release may be terminated, in
        whole or in part, by PairGain, upon written notice to VINA, in the event
        another party acquires a controlling interest in VINA (controlling not
        necessarily requiring greater than 50%) or a majority equity
        participation in VINA, without a prior written guarantee from such party
        to PairGain that such party will continue to abide by the terms of this
        Agreement.

25.3    The Agreement and/or any Purchase Order or Release may be terminated, in
        whole or in part by either Party, upon a thirty (30) calendar day
        written notice, in the event the other Party fails to execute any one of
        its material obligations hereunder and fails to remedy the default after
        receiving written notice within said period of thirty (30) calendar
        days.

25.4    Above termination rights shall be in addition to other termination
        rights contained herein, including under Section 4 (Delivery), and shall
        be without prejudice to the rights or claims one Party may have against
        the other with respect to the performance, non-performance, or breach of
        such Party's obligations hereunder, and shall not operate so as to
        extinguish any rights or obligations which arose prior to the date of
        termination, and each Party shall have the right to pursue each and
        every available remedy at law and in equity, including, without
        limitation, withholding payments of any amount owed by PairGain to VINA
        pending resolution of any claims made by PairGain in good faith against
        VINA.

25.5    In the event this Agreement is terminated by VINA for default by
        PairGain or for any other reason hereunder, PairGain and its customers
        shall thereafter retain such rights, as may be necessary in order to
        allow PairGain and its customers to provide Product support and
        maintenance to their end-user customers, provided however the Products,
        in respect of which support and maintenance services will be provided,
        have been paid for by PairGain.

25.6    This Agreement may be terminated upon agreement of the Parties to that
        effect.

25.7    PairGain agrees not to manufacture a competitive solution to VINA's HDSL
        Integrator or T1 Integrator (Competitive Product), except any products
        that are available to PairGain through existing partnerships or is in
        production by PairGain within the next six months, specifically the
        DSLAM products. If PairGain decides to manufacture, market or resell a
        competitive solution, VINA has the right to terminate the contract
        between both parties after written agreement by PairGain that the
        product is a Competitive Product. If the parties cannot agree if the
        solution is a Competitive Product, then the same mediation process as in
        section 8 will be used.

25.8    Notwithstanding any termination or expiry of this Agreement, the
        provisions of Sections 1 (Definitions), 8 (Product and Process Changes),
        7 (Prices and Payments), 11 (Technical Assistance), 15 (Warranty), 19
        (Continuing Availability of Technical Assistance, Repair Services,
        Maintenance, Replacement and Repair Parts), 22 (Confidential
        Information), 23 (Intellectual Property Right Infringement), 26
        (Indemnity), 27 (Consequential Damages),

                                       30
<PAGE>   32

        24 (Insurance) 25 (Termination and Continuing Rights), 33 (General) and
        all consequent rights, obligations and liabilities, shall survive the
        termination or expiry of this Agreement.

26.     INDEMNITY

26.1    Each Party shall indemnify and save harmless as "Indemnitees" the other
        and its employees, officers and directors from and against any and all
        fines, penalties, losses, costs, damages, injuries, claims, expenses or
        liabilities as a result of injury to, or death of, any person, or damage
        to, or loss or destruction of, any property, arising out of, or
        resulting from, or in connection with, this Agreement or the performance
        of this Agreement and caused by the negligence or willful misconduct of
        the indemnifying Party or a contractor or an agent of the indemnifying
        Party or an employee of any one of them (hereinafter individually and
        collectively "Liabilities").

26.2    Upon request of an Indemnitee, the other Party shall, at no cost or
        expense to such Indemnitee, defend or settle any suit or other legal
        proceeding asserting a claim for Liabilities, and the other Party shall
        pay any reasonable costs and attorneys' fees that may be incurred by
        such Indemnitee in connection with any such claim, proceeding or suit.

26.3    The Indemnitee shall as soon as practicable notify the other Party of
        the assertion of any such claim of which the Indemnitee is aware and the
        other Party shall (a) keep the Indemnitee subject to any such claim
        fully informed as to the progress of such defense, and (b) afford such
        Indemnitee, each at its own expense, an opportunity to participate fully
        with the other Party in the defense or settlement of any such claim, but
        the other Party shall have sole control of any such settlement or
        defense.

27.     CONSEQUENTIAL DAMAGES

27.1    Neither Party shall be liable pursuant to this Agreement for any
        incidental or consequential damages or for any damages for loss of
        profits or revenues, except (a) VINA shall pay, without limitation, all
        litigation costs, reasonable attorneys' fees, settlement payments and
        any damages awarded or resulting from any suit, claim or proceeding as
        set forth in Section 23.2 of this Agreement.

28.     MARKETING OF PRODUCT

28.1    In order to assist PairGain in its Product related marketing activities,
        PairGain may, at its option, request VINA to provide reasonable support
        in the following marketing activities:

        a)     VINA shall assist PairGain in providing point-by-point responses
               to RFQs (Request for Quotations) and RFIs (Request for
               Information) with respect to the Product.

                                       31
<PAGE>   33

        b)     VINA shall review and provide feedback on promotional material
               relating to the Product.

        c)     VINA shall make available to PairGain non-operational demo units
               which have the same "look" as the final Product at a price to be
               mutually agreed.

29.     NOTICES

29.1    Any and all notices or other information to be given by one of the
        Parties to the other hereunder or with respect to a Set of Schedules
        shall be sent by registered or certified mail, postage prepaid, or by
        telecopy or hand delivery to the other Party at the addresses set forth
        in Schedule H:

29.2    Notices given pursuant to this Section 29 shall be deemed to have been
        received five (5) business days after mailing if given by mail, and one
        business day after sending if given by telecopy and upon delivery if
        given by hand.

29.3    Either Party may change its address at any time by giving written notice
        to the other Party as provided above.

30.     INTENTIONALLY LEFT BLANK

31.     TERM

31.1    This Agreement shall come into force on the Effective Date and shall
        continue for a period of one (1) year thereafter and will be
        automatically renewable for successive twelve (12) month period(s), all
        such period(s) being referred to herein as "TERM", unless and until:

        (a)    terminated by either Party pursuant to Section 25, or

        (b)    the date on which the Parties agree that this Agreement will
               terminate, whichever is the earlier.

        (c)    The Parties agree that in no event shall the Term of this
               Agreement extend beyond five (5) years from the date of signature
               hereof.

        (d)    Unless either Party gives written notice to the other Party
               thirty (30) days prior to the Termination date.

32.     NORTH AMERICA FREE TRADE AGREEMENT - PROCEDURES

32.1    VINA shall perform all administrative actions required to qualify
        Product for preferential treatment under the rules of any applicable
        trade treaty between Canada, U.S.A. and

                                       32
<PAGE>   34

        Mexico including, without limitation, the North America Free Trade
        Agreement ("NAFTA"). If a Product qualifies under NAFTA, VINA shall
        prepare and distribute a NAFTA Exporter's Certificate of Origin
        according to Section 32.2 below, and any other documents required. VINA
        shall respond to NAFTA Exporter's Certificate of Origin questionnaires
        and assist each PairGain Company in resolving any Product eligibility
        issues. VINA alone shall bear responsibility for all penalties and costs
        resulting from a NAFTA Exporter's Certificate of Origin subsequently
        being determined to be invalid.

32.2    VINA shall (a) retain the original NAFTA Exporter's Certificate of
        Origin in VINA's files with appropriate backup documentation, (b) attach
        a copy of the NAFTA Exporter's Certificate of Origin to the
        customs/shipping documents for the qualifying Product, and (c) mark
        these customs/shipping documents with the legend: "Copy of the North
        America Free Trade Certificate of Origin attached."

33.     GENERAL

33.1    The failure of any Party to enforce at any time or for any period of
        time any of the provisions of this Agreement, shall not constitute a
        waiver of such provisions or the right of such Party to enforce each and
        every provision.

33.2    Neither Party shall assign or otherwise transfer all or any part of this
        Agreement or any payment to be made hereunder, or any interest herein,
        or any rights or obligations hereunder except as set forth below,
        without the prior written consent of the other Party, and such consent
        shall not be unreasonably withheld.

33.3    Each Party shall submit to the other all first-time advertising, sales
        promotion materials, press releases and other publicity matters relating
        to the Product wherein the name of the other Party or any of its
        affiliates is mentioned, or language from which the connection of said
        name therewith may be inferred or implied, and each Party further agrees
        not to publish or use such advertising, sales promotion materials, press
        releases, or other publicity matters without prior written approval of
        the other.

33.4    The construction, interpretation and performance of this Agreement shall
        be governed by the laws of the State of California, except for its rules
        with respect to the conflict of laws.

33.5    This Agreement, represents the entire agreement between the Parties with
        respect to the subject matter thereof and cancels and supersedes all
        prior agreements and communications on the said subject matter.

33.6    Publicly support industry forums, consortia and technologies that are
        concordant with both parties solution.

                                       33
<PAGE>   35

IN WITNESS WHEREOF, the Parties hereto have signed this Agreement by their duly
authorized representatives on the day, month and year first above mentioned.

PAIRGAIN TECHNOLOGIES INC.                    VINA TECHNOLOGIES, INC.

By: ROBERT R. PRICE                           By: STANLEY KAZMIERCZAK
   -----------------------------                 -------------------------------
               (Name)                                         (Name)

Title: Senior VP and  CFO                     Title: CFO
      --------------------------                    ----------------------------

Date: 6/23/2000                               Date: 6/23/00
     ---------------------------                   -----------------------------

                                       34
<PAGE>   36

                                   SCHEDULE A
         PRODUCT LIST, PRICES, DOCUMENTATION AND FCA DELIVERY LOCATIONS

I.      PRODUCT AND PRICES

        A.    PRODUCTS AND PRICES

               1. VINA - For the purposes of this contract, the VINA Product is
                  VINA Technology's HDSL Multiservice Integrated Access Device
                  (IAD) and the T1 Multiservice Integrated Access Device, also
                  commonly referred to as HDSL Integrator and T1 Integrator,
                  including all standard modifications and any special
                  modifications made specifically for PairGain but excluding any
                  customizations made specifically for other VINA customers.
                  VINA's HDSL Integrator and T1 Integrator Products are defined
                  below:

                                       35
<PAGE>   37

T1 Integrator
Model # V2-10-A-00-00-00-D

                                   [GRAPHIC]

CSU FUNCTIONALITY
T1 network interface
HDSL network   interface
Connector RJ-48C (keyed)
Monitor Jack:  Dual bantam
Line rate:  1.544 Mbps
Clock source:  Line (carrier)/Local (optional)
Line coding:  B8ZS or AMI
Framing:  D4 (SF) or ESF
Line build out:  0 dB,-7.5dB, or -15 dB
Automatic receive sensitivity

T1 PROVISIONING
Programmable between voice and data
Fractionally multiplexed voice and data
Both are programmable on a DS0 basis

CHANNEL BANK - FXS ANALOG SUPPORT
8-24 ports expandable in 4 or 8 port
increments
Loop start/ground start
Robbed bit line signaling
Modems supported - up to 28.8
48 volt battery
Ringing:  5 REN per port - 25 max per module
Tx and Rx Gain adjust:  0 dB, -3 dB or -6 dB
Impedance: 600 ohm
Trunkside signaling conversion
Local Call Routing (LCR) via FXO
DID termination
ANI/DNIS support
Digit Insertion

CHANNEL BANK - FXO ANALOG SUPPORT
Optional in 4 or 8 port increments
Loop start/ground start
Robbed bit line signaling
Ringing   1.5B REN
Impedance:  600  ohm

CHANNEL BANK - DIGITAL DSX-1 SUPPORT
Fractional T1 to PBX, Key System or Channel Bank
Connector RJ-48C (keyed)
Line rate:  1.544 Mbps
Clock source:  Local
Line coding:  B8ZS or AMI
Framing:  D4 (SF) or ESF
Line build out: 0-133 ft, 133-266 ft, 266-399 ft, 399-533 ft, 533-655 ft
Automatic receive sensitivity
Robbed bit line or trunk signaling supported FXS, FXO, E&M, DID, ANI, and DNIS
via PBX or Channel Bank

DSU PROVISIONING
Data rates: 64Kbps to 1.536Mbps in 64Kbps steps

IP/IPX NETWORKING
IP over Frame Relay
IPX over Frame Relay
HDLC (Cisco)
PPP
FRAME RELAY
LMI T1.617 annex D
LMI Q.933 annex A
IP over Frame Relay per RFC1490
Dual PVC's are supported

IP ADDRESS MANAGEMENT
DHCP (Dynamic Host Configuration Protocol)
automatically configures IP address for PC's.
IP address conservation

FIREWALL SUPPORT
SOCKS version 4 (application proxy) built in
Compatible with NetScape Navigator(tm) and Microsoft Internet Explorer (tm)
Only LAN initiated traffic is allowed through the firewall

                                       36
<PAGE>   38

External firewalls supported

ETHERNET PORT
10baseT
RJ-45 connector

CONSOLE PORT
DTE Interface
Baud rates: 9600, No parity, 8 bits, 1 start, 1 stop
Hardware flow control
Ready to connect to terminal, 28.8 modem, switched 56 or ISDN 64/128
Menu based management interface

MANAGEMENT
Statistics, status and configuration of all interfaces
Access via T1 or Ethernet
SNMP
        Version 1, MIB II
        MIBs supported:  TCP/IP, Frame Relay, T1
HTTP (compatible with industry standard WEB browsers)
Telenet
Console via RS232 (mdoem or terminal)
HTTP password protected with two privilege levels
Both Telnet and Console are password protected

POWER
120 VAC, 60Hz, 1 Amp
48 VDC, 50VA

PHYSICAL DIMENSIONS
Size:     17.0" W x 14.0" D x 1.75" H (IRU)

        "

Weight: 9.0 LBS
Mounting Configurations"
        Desktop
        Wall-mount
        19" Rack-mount
        23" Rack-mount

Clearence:
        Above            1.75"
        Below             0"
        Rear          0.6"
        Sides         2"
        Front         5"

CERTIFICATION
Compliance:    FCC Part 68, Industry Canada CS-03
Emissions:     FCC Part 15, Class A
Safety:        Listed: UL 1950,  C-UL
AT&T TR 62411, 54016
ANSI T1.403
EIA-464-B

Specifications subject to change without notice
(C) Copyright 1997 VINA Technologies

                                       37
<PAGE>   39

2. VINA WILL SELL TO PAIRGAIN THE "HDSL INTEGRATOR AND T1 INTEGRATOR" PRODUCT
(PRODUCT) AND ALL available plugs (Plugs) and peripherals at a ** discount
below VINA's list price, for sale into its Accounts, after all discounts.
PairGain will not sell the Product to accounts other those accounts presently
purchasing VINA products through and being supported by PairGain and any new
accounts in which PairGain and VINA mutally agree will be deemed PairGain
accounts. VINA's price sheet showing undiscounted prices is shown below for the
DSL Integrator and T1 Integrator and all available plugs (Product): This price
sheet shall be reviewed and updated at least annually with the latest list
prices released by VINA.

**CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       38
<PAGE>   40
[VINA LOGO]

<TABLE>
<CAPTION>
LIST PRICE ($US LIST)                                                    CONFIGURATION NUMBER                LIST PRICE
<S>                                                                    <C>  <C>  <C>  <C> <C>  <C>  <C>      <C>
T1 INTEGRATOR BASE CHASSIS
T1 Integrator(TM) Channel Bank equipped with single T1 interface,
integrated CSU/DSU, SNMP and power supply (AC or DC must
be specified)                                                          PG   30   A    0   00   00   00           **

T1 INTEGRATOR VOICE+DATA CHASSIS
T1 Integrator(TM) voice and data chassis equipped with
single T1 interface, integrated CSU/DSU, Frame Relay,
IP/IPX Routing, DHCP, NAT and Firewall, SNMP and
power supply (AC or DC must be specified)                              PG   10   A    0   00   00   00           **

T1 INTEGRATOR-16FXS  BASE CHASSIS
T1 Integrator(TM)-16FXS Channel Bank equipped with
single T1 interface, 16 FXS channels (16 analog
voice circuits) embedded in the chassis,
integrated CSU/DSU, SNMP and power supply
(AC or DC must be specified). This option
will leave one analog card slot                                        PG   30   A    0   e2   e2   00           **

T1 INTEGRATOR-16FXS  VOICE+DATA CHASSIS
T1 Integrator(TM)-16FXS voice and data chassis equipped
with single T1 interface, 16 FXS channels (16 analog
voice circuits) embedded in the chassis, integrated
CSU/DSU, Frame Relay, IP/IPX Routing, DHCP, NAT and
Firewall, SNMP and power supply (AC or DC must be specified)           PG   10   A    0   e2   e2   00           **

HDSL INTEGRATOR BASE CHASSIS
HDSL Integrator(TM) Channel Bank equipped with single
HDSL interface, integrated CSU/DSU, SNMP and power
supply (AC or DC must be specified)                                    PG   70   A    0   00   00   00           **

HDSL INTEGRATOR VOICE+DATA CHASSIS
HDSL Integrator(TM) voice and data chassis equipped
with single HDSL interface, integrated CSU/DSU,
Frame Relay, IP/IPX Routing, DHCP, NAT and Firewall,
SNMP and power supply (AC or DC must be specified)                     PG   60   A    0   00   00   00           **

OPTIONS AT TIME OF INITIAL ORDER
Battery Backup                                                         BBKUP                                     **
</TABLE>

<TABLE>
<CAPTION>
OPTIONS & SPARES                                   MODEL NUMBER         LIST PRICE
<S>                                                <C>                  <C>
HARDWARE
4 channel FXS card                                 V2-4P-FXS                **
8 channel FXS card                                 V2-8P-FXS                **
4 channel FXO card                                 V2-4P-FXO                **
8 channel FXO card                                 V2-8P-FXO                **
Fractional T1 Card                                 V2-FT1                   **
Fractional T1 and DSP Combination Card             V2-FT1-DSP               **
Telco DSP Processor                                V2-DSP                   **
Fractional T1-V.35 convertor module                V2-V.35                  **

SOFTWARE
TR08 module                                        SW-TR08                  **
Local Call Routing (LCR)                           SW-LCR                   **
Business OfficeXchange (BOX)                       SW-BOX                   **
Frame Relay Service Level Agreement
Statistics (SLAs)                                  SW-SLA                   **
Data Upgrade (for field upgrade - post
initial time of order)                             SW-D                     **

ADDITIONAL OPTIONS
NEBS (GR63) install kit                            NEBS                     **
Hinged Mount Assembly Kit                          HNGMNT                   **
Bellcore Rack Mount Assembly Kit                   BBRKTS                   **
10ft RJ21 cable with 66 block package              CBL1                     **
30ft RJ-48 cross over cable                        CBL2                     **
Power Cord Hold down                               PWRCRD-HLD               **

POWER SUPPLY
AC Supply                                          AC                       **
DC Cable                                           DC                       **
Battery Backup (for field upgrade - post
initial time of order)                             BBKUP-UPG                **
</TABLE>

*Non discountable
 All prices FOB origin. Prices are subject to change without notice

**CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       39
<PAGE>   41
[VINA LOGO]

T1/HDSL INTEGRATOR CONFIGURATION & ORDERING TOOL

Selections MUST be made for every option in both sections: System Configuration
& Software Feature Configuration

SYSTEM CONFIGURATION

ANALOG VOICE SLOT CONFIGURATION

<TABLE>
<CAPTION>
                                              SYSTEM CONFIGURATION NUMBER (SCN):

                                              MODEL NO.                 CONFIG #
<S>                                  <C>      <C>                       <C>

1. SELECT A CHASSIS                           T1 Channel Bank             [30]
                                              T1  Voice+Data Chassis      [10]
                                              HDSL Channel Bank           [70]
                                              HDSL Voice+Data Chassis     [60]

2. SELECT A POWER CONNECTION                  AC                          [A]
                                              DC                          [D]

3. SELECT A FRACT. T1/DSP                     V2-FT1                      [F]
DSP is needed when LCR or BOX                 V2-DSP                      [D]
software is ordered                           V2-FT1-DSP                  [B]
                                              None                        [0]

4. VOICE CARD OPTIONS:

Make a selection for each voice
slot                                 SLOT 1:  V2-4P-FXS                   [01]
                                              V2-8P-FXS                   [02]
                                              V2-8P-FXS (embedded)        [e2]
                                              V2-4P-FXO                   [03]
NOTE: if [e2] is selected for
Slot 1, it                                    V2-8P-FXO                   [04]
MUST also be selected for slot 2              None                        [00]

The Embedded FXS option is only      SLOT 2:  V2-4P-FXS                   [01]
available for Chassis options                 V2-8P-FXS                   [02]
</TABLE>

                                       40
<PAGE>   42
[VINA LOGO]

                                  SPARES LIST

Issue Date: 9/1/98

SPARES OPTIONS

<TABLE>
<CAPTION>
ITEM                             MODEL NUMBER      DESCRIPTION
<S>                              <C>               <C>
1. VOICE CARDS                   V2-4P-FXS         4 Port FXS card for the V2
                                 V2-8P-FXS         8 Port FXS card for the V2
                                 V2-4P-FXO         4 Port FXO card for the V2
                                 V2-8P-FXO         8 Port FXS card for the V2

2. FRACTIONAL T1, DSP & V.35     V2-FT1            Fractional T1 card
                                 V2-DSP            Telco DSP card
                                 V2-FT1-DSP        Fractional T1 & DSP Combo
                                 V2-V.35           Fractional T1-V.35 convertor
                                                  (requires a V2-FT1 or V2-FT1-DSP)

3. POWER SUPPLY                  AC                AC power supply
                                 DC                DC power cable
                                 BBKUP             Battery Backup

4. NEBS KIT                      NEBS              NEBS (GR-63) Installation Kit

4. BOX REFERENCE GUIDE           BOX-REF           BOX User Guides (Package  of 25 pamphlets)

SOFTWARE FEATURE OPTIONS         SW-D              Software for Data Module
(Select all required features)   SW-LCR            Local Call Routing
                                 SW-TR08           TR08 (SLC) software
                                 SW-BOX            Business OfficeXchange
                                 SW-VPN            Virtual Private Networking
</TABLE>

NOTE:
LCR requires FXO voice cards
LCR  and BOX require a DSP

                                       41
<PAGE>   43

           3.  VINA will sell to PairGain a standard warranty and service
               extension, on a per year basis, beyond the 3 year negotiated
               warranty offering, ** per year of the then list price of the
               VINA product for all product purchased pursuant to this contract.

           4.  PAIRGAIN - The table below specifies HDSL module preferential
               pricing for 2000. PairGain shall extend in good faith deeply
               discounted pricing to VINA on PairGain's family of DSL modules
               which will be installed in the DSL Integrator and T1 Integrator.
               VINA and PairGain agree to re-negotiate in good faith the HDSL
               module pricing on a yearly basis. Pricing must be established by
               January 1 of each year.

<TABLE>
<CAPTION>
                  HDSL                                                YEAR
                  --------------------------------------------------------
<S>                                                                   <C>
                  **                                                  2000
</TABLE>

        B. REPORTS

<TABLE>
<CAPTION>
           Reports:                                       Reference Section
<S>        <C>                                                          <C>
           Field Baseline Report                                      8.8
           VINA Subcontractor ISO 9002 Certificate                    9.1.1
33.7         Unit Failure Analysis               15.10, 17.2e
           Hazardous and/or toxic materials                           21.2
           Product Requalification when changes have been made        9.5.1
</TABLE>

        C. TECHNICAL ASSISTANCE AND SUPPORT

           VINA's Technical Assistance Center (TAC) will provide, defined later
           in this document, level 2 support during the warranty period of the
           product at no charge to PairGain, providing the support request is
           originated by designated PairGain personnel, which have been
           certified via VINA certified training programs. Level 2 support will
           be provided on out of warranty product at the then current VINA
           hourly rates. Should emergency onsite support be requested, within
           the product warranty period, by certified PairGain personnel, all
           travel, lodging, and hourly expenses of VINA personnel will be the
           responsibility of PairGain, unless it is determined by VINA personnel
           that the root cause of the problem is directly attributable to the
           VINA product. Should emergency onsite support be requested, after the
           product warranty period has expired, all travel, lodging, and the
           then current hourly rate of VINA personnel will be the responsibility
           of PairGain.

** CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       42
<PAGE>   44

<TABLE>
<S>                                                    <C>
            Assistance                                 Reference Section
            Technical Assistance                       11.3
            Other Technical Assistance                 11.6
            Retest of Product                          17.4.3
            Technical Assistance Level 2 Support       Schedule G, II, 3
            On Site Support                            Schedule G, II, 4
            Other Technical Support                    Schedule G, II, 5
</TABLE>

D.      Technical Assistance Support Rates

               Hourly phone = **
               On site - flat = **

II.     DOCUMENTATION

        PRODUCT       TECHNICAL PRACTICE

        TO INCLUDE A LIST OF ALL DOCUMENTATION TO BE PROVIDED BY VINA

III.    FCA DELIVERY LOCATIONS:

        For all Product:            FOB shipping point

** CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       43
<PAGE>   45

                                   SCHEDULE B
                 SPECIFICATIONS AND ACCEPTANCE PROGRAM SCHEDULE

PART I:        SPECIFICATIONS

1.      DOCUMENT IDENTIFICATION:

        (Should specify VINA specification document(s) Include Document Code:
        Date: Latest version signed and dated by the Parties.

        REGULATORY/APPROVALS REQUIREMENTS

        The Product should:

           a) meet or exceed FCC Part 15 requirements for a Class A device.

           b) meet or exceed comparable UL and Canadian CSA requirements

           c) comply with EMC requirements only, not including other portions
              of the spec such as static electricity tests, outlined in Bellcore
              GR-1089 if needed by the customers

           d) comply with the portions of Bellcore Network Equipment-Building
              System (NEBS) Generic Equipment Requirements (TR-NWT-000063) that
              apply if needed by the customers.

        Should other certifications be required, they shall be discussed between
        VINA and PairGain. VINA shall use its best efforts in supporting
        PairGain's regulatory activities.

        PRODUCT MARKING

        1.    Serial number: should be placed on unit as per Bellcore GR-78.

        2.    Manufacturing date on the Printed Circuit Assembly (PCA): should
              be placed on unit as per Bellcore GR-78.

        3.    PairGain's logo and model number on faceplate. 4. Repair Date
              stamp: VINA shall date stamp each repaired and returned Product
              with the repair date and type of repair "prefix" as per Bellcore

        4.    Product marking and packaging requirements pursuant to this
              Agreement:

              a)    Bellcore GR-CORE-1421 and TR-NWT-000063;
              b)    Bellcore TR-NWT-870 on ESD protection;

PACKING

VINA shall package the Products for shipment utilizing the same containers that
are used for VINA standard product with the PairGain Logo in lieu of the VINA
logo. The packaging should, when necessary, utilize standard ESD protective
measures. The packaging should be in

                                       44
<PAGE>   46

accordance with Bellcore's GR-CORE-1421, TR-NWT-000063 and TR-NWT-870 standard
packing practices, with any modifications specified by PairGain and agreed to by
VINA, related to the size and external markings and/or labels (including
branding) of the boxes. VINA and PairGain will work together in exchanging any
relevant information (artwork, label artwork, etc.) to facilitate packaging.
VINA shall be responsible for any damage to Products including damage caused by
packing noncompliant with Bellcore

        Support groups:      VINA's Operations group
                             PairGain's OEM group

PART II:       PRODUCT ACCEPTANCE PROGRAM

1.    In order to verify that the Product or modified Product from VINA comply
      with the applicable Specifications, PairGain will undertake an Acceptance
      Program covering verification and Product integrity testing. In this
      regard, VINA recognizes that much of the value of the Product lies in
      their ability to integrate with various telecommunications systems.

2.    VINA shall loan to PairGain, at no charge to PairGain, four (4) units for
      up to 90 days as negotiated by PairGain and VINA, for a specific period of
      time such Product and test procedures, as are necessary to perform the
      Acceptance Program, and shall provide support to the PairGain group during
      the testing. Such support includes diligence in replacing failed Product,
      availability of technically knowledgeable individuals to discuss testing
      results and teaming of at least one VINA individual with PairGain testing
      group for all tests to occur on the premises of either of the Parties.
      PairGain shall endeavor to limit as much as possible the Product needed
      for the acceptance in terms of number of modules and duration of the loan
      by taking into consideration design commonalties with already-accepted
      Product.

3.    Each new design or change to existing Product as per Section 8 (PRODUCT
      AND PROCESS CHANGES) shall be tested and/or approved by PairGain's
      Technical Support group or Quality department. VINA shall provide PairGain
      with updated documentation to address revisions in the Product, and in
      this regard, all manuals shall contain revision marks in order to
      facilitate identification of changes in the text. VINA shall also provide
      PairGain with an Acceptance Test Procedure for testing each new design or
      change.

                                       45
<PAGE>   47

4.    Primeships:

      PairGain's Technical Support group is prime for the verification testing
      and for the Product integrity testing; PairGain's Quality department is
      prime for approval of Process Changes. VINA's Engineering department is
      prime for supporting PairGain's Acceptance Program.

                                       46
<PAGE>   48

                                   SCHEDULE C
       REPAIR AND REPLACEMENT RATES, EMERGENCY REPLACEMENT PRODUCT AND FCA
                                REPAIR LOCATIONS

I.      Repair and Replacement Rates

         VINA will provide, at their discretion, repair or replacement during
         the warranty period of the product at no charge except for shipping
         cost of Product to VINA, to PairGain providing the repair or
         replacement request is originated by designated PairGain personnel.
         Repair parts or replacement product will be shipped only when deemed
         appropriate following a troubleshooting session with a VINA support
         engineer. PairGain must return the defective part, as established in
         section 16.2, to VINA within fortyfive business days, after fortyfive
         business days the replacement part will be invoiced. For product out of
         warranty, repair and return is charged on a per item basis at the then
         current VINA hourly rates as provided in this Schedule C, not to exceed
         ** of the current list price of the Product, providing the repair or
         replacement request is originated by designated PairGain personnel.
         Repair parts or replacement product will be shipped only when deemed
         appropriate following a troubleshooting session with a VINA support
         engineer.

II.     Emergency replacement Product

        (as per section 18.1)

III.    FCA Repair Locations

        VINA Technologies
        42709 Lawrence Place
        Fremont, CA 94538

IV.     Repair Rates

        Hourly cost for repair is **

** CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       47
<PAGE>   49

                                   SCHEDULE D

                               CHANGE NOTIFICATION

<TABLE>
<S>                     <C>                                        <C>
--------------------------------------------------------------------------------------------
1.  SUPPLIER INFORMATION:                                          2. PRODUCT CHANGE NOTICE:
                             VINA                                     1998xxxx
                                                                   ISSUE:  01
--------------------------------------------------------------------------------------------
3.  ISSUE DATE:         4. PRODUCT IDENTIFICATION:
                                  MAJOR SYSTEM:
                                  SUB SYSTEM  :
                                  HWARE: ?   FWARE: ?   SWARE: ?  PLUGIN: ?
--------------------------------------------------------------------------------------------
5.  NEW PROD    RLSE    6. OLD PROD  RLSE    7. NEW CLEI    CODE  8. OLD CLEI CODE
    NTxxxxxx    tbd        NTxxxxxx    03       tbd                         SNMYACAFAA
--------------------------------------------------------------------------------------------
9.  ASSOCIATED PRODUCTS OR CHANGES AFFECTED:

--------------------------------------------------------------------------------------------
10. DRAWING NUMBER:                                         11. CHANGE CLASSIFICATION:
    ADxxxxxx                                                    A/AC/B.......
--------------------------------------------------------------------------------------------
12. CLASSIFICATION SUBSTANTIATION:

--------------------------------------------------------------------------------------------
13. REASON FOR CHANGE:

--------------------------------------------------------------------------------------------
14. DESCRIPTION OF CHANGE:

    VERIFICATION PROCEDURES:

    BACKOUT PROCEDURES:

--------------------------------------------------------------------------------------------
15. EFFECT OF CHANGE:
    Enhanced features and easier installability.

    SAFETY HAZARD: ?   FIRE HAZARD : ?   SRVC AFFCTG: ?   TRANS AFFCTG: ?
    MNTNCE AFFCTG: ?   RELIA AFFCTG: ?   POWR AFFCTG: ?   TRAF  AFFCTG: ?
--------------------------------------------------------------------------------------------

16. MATERIAL AFFECTED:
--------------------------------------------------------------------------------------------
17. DOCUMENTATION AFFECTED:

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

18. IMPLEMENTATION DATE:                      19. CHANGE COMPLETION DATE:
    MM/DD/YY                                             N/A
--------------------------------------------------------------------------------------------
</TABLE>

                                       48
<PAGE>   50

<TABLE>
<S>                     <C>                                        <C>
--------------------------------------------------------------------------------------------
20. MODIFICATION LOCATION:
    N/A

    TRIALED: N (Field Lab Na)
--------------------------------------------------------------------------------------------
21. INSTALLATION HOURS AND MATERIAL COST:
    HOURS: N/A
    COST : N/A

--------------------------------------------------------------------------------------------
22. LOCATION AND QUANTITY OF EQUIPMENT:
    N/A

--------------------------------------------------------------------------------------------
23. ATTACHMENTS:
    None

--------------------------------------------------------------------------------------------
24. COMMENTS:
</TABLE>

                                       49
<PAGE>   51

                                   SCHEDULE E
                          CANCELLATION AND RESCHEDULING

SECTION I:     PURCHASE ORDER CANCELLATIONS

1. In the event of cancellation of all, or a part of, a Purchase Order,
   PairGain's sole liability to VINA shall be as follows:

    (A)  Notice of cancellation provided zero (0) to thirty (30) days before
         scheduled shipment date:

               (a)
                      ** of the total value of the canceled Purchase Order or
                      the part thereof which is canceled.

    (B)  Notice of cancellation provided over thirty-one (31) days before
         scheduled shipment date for any period: no charge.

2.       PairGain's liability pursuant to Section 1 above shall be reduced up to
         ** in the event that material can be used for other Purchase Orders
         placed hereunder. In addition VINA shall use all reasonable endeavors
         to minimize any such cancellation costs by, inter alia, selling the
         Product to another customer, returning components to suppliers,
         reducing cancellation costs to suppliers, any such savings will be
         passed onto PairGain. Prior to selling canceled Product or part
         thereof, to another customer, to the extent permitted under this
         Agreement, VINA shall, as part of the restocking process and included
         in the cancellation charge, remove any PairGain branding and other
         PairGain specified superficial markings that had already been applied
         to the canceled Product at the time of receipt of PairGain's
         cancellation notice. In case VINA does not comply with this Section 3,
         VINA shall bear the costs to correct the situation.

3.       The foregoing constitutes PairGain's sole liability and VINA's sole
         remedy in the event of PairGain's cancellation of Purchase Orders.

SECTION II:    RESCHEDULING

1.       PairGain may, at any time, for its convenience and without cause, by
         written notice issued to VINA prior to the Delivery Date, reschedule
         the Delivery Date of ordered Product provided such rescheduled Delivery
         Date shall not exceed thirty (30) days from the date the Product was
         originally scheduled to be delivered. Delivery of Product covered by
         any individual Purchase Order or Release cannot be postponed more than
         once.

         Rescheduling in less than ten (10) business days from the Delivery Date
         shall be subject to a ** restocking fee calculated on the Price
         applicable to the rescheduled portion of

** CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.

                                       50
<PAGE>   52

         the Purchase Order or Release and such restocking fee shall constitute
         PairGain's sole liability and VINA's sole remedy in the event of the
         rescheduling of the Purchase Order or Release.

                                       51
<PAGE>   53

                                   SCHEDULE F
          PROCEDURES FOR ORDERS UTILIZING ELECTRONIC AND TECHNICAL DATA
                            INTERCHANGE TRANSMISSION

VINA has not implemented EDI transmission at this time. This section can be
     reviewed and added at a later date if warranted.

                                       52
<PAGE>   54

                                   SCHEDULE G
                              TECHNICAL ASSISTANCE

I.      TECHNICAL ASSISTANCE BY PAIRGAIN

1.      It shall be PairGain's responsibility to provide 'first line' (Level 1)
        technical assistance and support to its customers. PairGain's customers
        will never contact VINA directly. PairGain will at its option provide
        any of the following services to its customers as Level 1 support.

        Level 1 Support:

             - Telephone Service Desk
             - On site support
             - Preventative maintenance
             - Monitor alarms/malfunctions
             - Corrective action and logging
             - Product alarm knowledge
             - Escalate and report
             - Remote modem access
             - Log and track problems
             - Isolate sub system faults
             - Product temporary system solutions
             - Software upgrade loads distribution to Customers
             - Multi-vendor product expertise
             - Board and module swap
             - Product training
             - Analyze and record Fast Cycle Failure Analysis report

II.     TECHNICAL ASSISTANCE BY VINA

    1.  VINA shall provide at no cost to PairGain Product training documentation
        and information. VINA shall provide train-the-trainer sessions for
        PairGain's training personel. VINA shall train a maximum of ten (10)
        PairGain technicians in a three (3) day session, such group to act as
        the first line of support to the customers' inquiries.

        a) TRAIN-THE-TRAINER REQUIREMENTS

           VINA shall provide training to PairGain's Training department for
           major revisions of Product, at least one month prior to release of
           the product, as well as a semi-annual update.

                                       53
<PAGE>   55

           PairGain's Training department should be provided with hardware for
           new products prior to release.

        b) VINA TECHNOLOGIES HDSL INTEGRATOR AND T1 INTEGRATOR TRAINING SYSTEM,
           TRAINING REQUIREMENTS FOR TECHNICIANS

           Installation and Commissioning Engineers

           Installation and commissioning engineers should have sufficient
           knowledge of the equipment to determine the correct installation
           requirements for the task at hand. They should be aware of any
           special requirements (e.g., cooling, cable routing, grounding) and
           therefore have a thorough knowledge of the equipment's operating
           parameters as well as the installation requirements. Installation and
           commissioning engineers should be able to recognize and name all the
           system components and have a general knowledge of each component's
           functionality and fault conditions. An operating knowledge of the
           equipment is required to implement basic connections at the
           T1/E1level in accordance with the VINA Technologies user guides and
           to commission the unit to a state where it can be managed by the
           network operators. Detailed operating knowledge is not required.

           Operation, Administration and Maintenance Engineers

           Operation, administration and maintenance (OA&M) engineers are
           required to have a far more comprehensive knowledge of the
           equipment's operation than the installation and commissioning
           engineer. They should therefore be able to carry out all the
           functions of the installation and commissioning engineer. OA&M
           engineers should be able to describe in detail the equipment's core
           applications and have a general knowledge of the HDSL Integrator and
           T1 Integrator Functionality. They should also have a good
           understanding of how the various platform technologies are employed,
           e.g., configuring a HDSL Integrator and T1 Integrator for voice and
           data transmission. A detailed knowledge of the equipment's
           configuration parameters and maintenance features is required. OA&M
           engineers should be able to configure all of these functions under
           the RS-232 terminal interface.

           Network Operators

           Network operators are required to have a comprehensive knowledge of
           the HDSL Integrator and T1 Integrator as driven by the Telnet
           session, or the HTTP interface via Web Browser, including the use of
           on-line help. Operators should be able to recognize commonly used
           icons. Using the Telnet session, or the HTTP interface via Web
           Browser, network operators should be able to carry out all basic and
           detailed configuration tasks on the various service configurations of
           the HDSL Integrator and T1 Integrator. A full understanding of the
           SNMP functions and their use is required. Network operators should be
           able to recognize fault conditions and have an understanding of the
           problem tracking systems, diagnostic tools and their use. A

                                       54
<PAGE>   56

           general knowledge of the enhanced facilities available (e.g.,
           diagnostics) is also required.

           Upon satisfactory completion of individual training courses, PairGain
           personnel will receive certification from VINA in the form of
           letters, or certificates of accomplishment, which will fulfill the
           necessary training requirements to provide level 1 support.

2.      In order to facilitate PairGain's support of its customers, VINA shall
        provide to designated PairGain personnel only, without charge, telephone
        access to qualified VINA's technical personnel with the following
        structure:

        i)     Non Urgent Technical Support

        Telephone service will be available in the following form:

        Between the hours of 8:00 AM and 5:00 PM PST (Pacific Standard Time)
        between Monday and Thursday a single number which will always be
        answered by a person and not an electronic secretary shall be provided.
        The telephone number to reach VINA's technical support personnel at all
        times is: 510-413-1353, or 888-774-8462. The wait period for qualified
        technical assistance shall not exceed ninety (90) minutes.

        ii)    Urgent Technical Support

        Telephone service will be available twenty-four (24) hours a day, seven
        (7) days a week. The telephone number to reach VINA's emergency support
        personnel at all times is No. 888-774-8462, or 510-492-0800. If a call
        back (pager) system is used, the wait period for qualified technical
        assistance shall not exceed) sixty (60) minutes.

        VINA shall advise PairGain of any telephone number change for this
        service at least thirty (30) days prior to the change.

3.      VINA shall provide, at no cost, to PairGain and to PairGain's customers
        "Second line" (Level 2) technical assistance which will include the
        following services:

        Level 2 Support

             - Assistance at the request of PairGain
             - VINA technical support contacts (24 hours a day)
             - Log and track problems
             - Isolate sub-system and design faults (in house)
             - In-house simulation and testing
             - Remote modem access to PairGain's TAC center
             - Deliver software upgrade and software builds to PairGain's
               distribution center
             - Escalation and reporting to PairGain
             - Emergency Site Support (at customer/PairGain site)

                                       55
<PAGE>   57

             - Perform Root Cause Analysis
             - Emergency Spares holding (at VINA's premises) as per Section 17
             - Design authority support interfaces
             - Analyze and resolve design problems (Hardware and System
               Software), prepare patches and modifications, incorporate them in
               new builds, test perform sanity checks and deliver the builds and
               Hardware and System Software to PairGain's distribution center
             -
             - Fast Cycle Failure Analysis at the request of PairGain

4.      VINA will provide on-site support and assistance to PairGain in a
        reasonable time frame and at a reasonable cost which may include travel
        and lodging cost to PairGain in the following cases.

        a) In cases where PairGain was unable to resolve a problem through
           normal maintenance activities and technical support provided remotely
           by VINA.

        b) In cases where PairGain is able to resolve a problem but cannot
           determine the root cause of the problem.

        c) In cases where a problem with the Product leads a customer to
           specifically request technical presence.

        d) bIn cases where a problem with the Product exists in the field and
           VINA's presence is requested by PairGain Senior Management.

5.      Any other technical support which VINA shall provide to PairGain or its
        customers shall be pursuant to a written request from PairGain's
        designated personnel, or such other individual designated, from time to
        time, by PairGain. Such support shall be at prices set forth in Schedule
        A and on terms and conditions agreed upon by the Parties.

6.      Technical assistance support will be provided remotely to PairGain
        and/or to the customer in conjunction with PairGain, but not by VINA
        alone (unless authorized in writing to do so by PairGain).

7.      VINA will provide Response Time and Mobilization based on the Problem.

                                       56
<PAGE>   58

                                   SCHEDULE H

                                     NOTICES

PAIRGAIN                            VINA

Abe Ali - OEM Sales Mgr             Stan Kazmierczak, Chief Financial Officier
19196 Highland View Lane            42709 Lawrence Place
Trabuco Canyon, CA  92678           Fremont, CA  94538

Tel:949-713-5002                    510-413-1333
Facsimile:949-713-5003              510-492-0808
email: abe_ali@pairgain.com         kaz@vina-tech.com

CONTRACTUAL:

PairGain Technologies, Inc          VINA Technologies
14402 Franklin Avenue               42709 Lawrence Place
Tustin, CA 92780-7209               Fremont, CA  94538

Attn: Rob Price                     Attn: Stan Kazmikerczak - CFO
Tel: 714-730-2916                   510-413-1333
Facsimile No: 714-832-9901          510-492-0808

                                       57<PAGE>   1

                                                                    EXHIBIT 4.01

                          WASATCH PHARMACEUTICAL, INC.
                      2000 Non-Qualified Stock Option Plan

Wasatch Pharmaceutical, Inc., a Utah corporation (the "Company"), hereby adopts
this 2000 Non-Qualified Stock Option Plan (the "Plan"), this 2nd day of July,
2000, under which options to acquire stock of the Company may be granted from
time to time to employees and consultants of the Company or its subsidiaries. In
addition, at the discretion of the board of directors, options to acquire stock
of the Company may from time to time be granted under this Plan to other
individuals who contribute to the success of the Company or its subsidiaries and
are not employees of the Company, all on the terms and conditions set forth
herein.

        1. PURPOSE OF THE PLAN. The Plan is intended to aid the Company in
maintaining and developing a management team, attracting qualified officers and
employees capable of assisting in the future success of the Company, and
rewarding those individuals who have contributed to the success of the Company.
It is designed to aid the Company in retaining the services of executives and
employees and in attracting new personnel when needed for future operations and
growth and to provide such personnel with an incentive to remain employees of
the Company, to use their best efforts to promote the success of the Company's
business, and to provide them with an opportunity to obtain or increase a
proprietary interest in the Company. It is also designed to permit the Company
to reward those individuals who are not employees of the Company but who are
perceived by management as having contributed to the success of the Company or
who are important to the continued business and operations of the Company. The
above aims will be effectuated through the granting of options ("Options") to
purchase shares of common stock of the Company, par value $0.001 per share (the
"Stock"), subject to the terms and conditions of this Plan.

        2. EFFECTIVE DATE. The Plan shall become effective immediately on
adoption by the board of directors of the Company (the "Board").

        3. ADMINISTRATION OF THE PLAN. Administration of the Plan shall be by
the Board. Subject to compliance with applicable provisions of the governing
law, the Board may delegate administration of the Plan or specific
administrative duties with respect to the Plan, on such terms and to such
committees of the Board as it deems proper; provided however, that if less than
the entire Board is administering the Plan or grants under the Plan, action may
be taken only by a committee of two or more "disinterested directors" as that
term is defined in Rule 16b-3, and the regulations and releases thereunder all
as promulgated by the Securities and Exchange Commission under authority of the
Exchange Act of 1934, as amended. Any Option approved by the Board shall be
approved by a majority vote of those members of the Board in attendance at a
meeting at which a quorum is present. Any Option approved by a committee
designated by the Board shall be approved as specified by the Board at the time
of delegation. The interpretation and construction of the terms of the Plan by
the Board or a duly authorized

<PAGE>   2

committee shall be final and binding on all participants in the Plan absent a
showing of demonstrable error. No member of the Board or duly authorized
committee shall be liable for any action taken or determination made in good
faith with respect to the Plan.

        4. SHARES OF STOCK SUBJECT TO THE PLAN. A total of four million
(4,000,000) shares of Stock may be subject to, or issued pursuant to, Options
granted under the terms of this Plan. Any shares subject to an Option under the
Plan, which Option for any reason expires or is forfeited, terminated, or
surrendered unexercised as to such shares, shall be added back to the total
number of shares reserved for issuance under the terms of this Plan, and if any
right to acquire Stock granted under the Plan is exercised by the delivery of
shares of Stock or the relinquishment of rights to shares of Stock, only the net
shares of Stock issued (the shares of Stock issued less the shares of Stock
surrendered) shall count against the total number of shares reserved for
issuance under the terms of this Plan.

        5. RESERVATION OF STOCK ON GRANTING OF OPTION. At the time of granting
any Option under the terms of this Plan, there will be reserved for issuance on
the exercise of the Option the number of shares of Stock of the Company subject
to such Option. The Company may reserve either authorized but unissued shares or
issued shares that have been reacquired by the Company.

        6. ELIGIBILITY. Options under the Plan may be granted to employees,
including officers, and directors of the Company or its subsidiaries, as may be
existing from time to time, and to other individuals who are not employees of
the Company, but performed bona fide services to the Company, as may be deemed
in the best interest of the Company by the Board or a duly authorized committee.
Such Options shall be in the amounts, and shall have the rights and be subject
to the restrictions, as may be determined by the Board or a duly authorized
committee, all as may be within the general provisions of this Plan.

        7. TERM OF OPTIONS AND CERTAIN LIMITATIONS ON RIGHT TO EXERCISE.

        (a) Each Option shall have the term established by the Board or duly
authorized committee at the time the Option is granted but in no event may an
Option have a term in excess of five (5) years.

        (b) The term of the Option, once it is granted, may be reduced only as
provided for in this Plan and under the written provisions of the Option.

        (c) Unless otherwise specifically provided by the written provisions of
the Option, no holder or his or her legal representative, legatee, or
distributee will be, or shall be deemed to be, a holder of any shares subject to
an Option unless and until the holder exercises his or her right to acquire all
or a portion of the Stock subject to the Option and delivers the required
consideration to the Company in accordance with the terms of this Plan and then
only to the extent of the number of shares of Stock acquired. Except as
specifically provided in this Plan or as otherwise specifically provided by the
written provisions of the Option, no adjustment to the exercise price or the
number of shares of Stock subject to the Option shall be made for dividends or
other rights for which the record date is prior to the date the Stock subject to
the Option is acquired by the holder.

        (d) Options under the Plan shall vest and become exercisable at such

                                       2
<PAGE>   3

time or times and on such terms as the Board or a duly authorized committee may
determine at the time of the grant of the Option.

        (e) Options granted under the Plan shall contain such other provisions,
including, without limitation, further restrictions on the vesting and exercise
of the Option, as the Board or a duly authorized committee shall deem advisable.

        (f) In no event may an Option be exercised after the expiration of its
term.

        8. EXERCISE PRICE. The exercise price of each Option issued under the
Plan shall be determined by the Board or a duly authorized committee on the date
of grant.

        9. PAYMENT OF EXERCISE PRICE. The exercise of any Option shall be
contingent on receipt by the Company of cash, certified bank check to its order,
or other consideration acceptable to the Company; provided, that at the
discretion of the Board or a duly authorized committee, the written provisions
of the Option may provide that payment can be made in whole or in part in shares
of Stock of the Company, which Stock shall be valued at its then fair market
value as determined by the Board or a duly authorized committee, or by the
surrender or cancellation of other rights to Stock of the Company. Any
consideration approved by the Board or a duly authorized committee, that calls
for the payment of the exercise price over a period of more than one year shall
provide for interest, which shall not be included as part of the exercise price,
that is equal to or exceeds the imputed interest provided for in section 483 of
the Code or any amendment or successor section of like tenor.

        10. WITHHOLDING. If the grant or exercise of an Option pursuant to this
Plan is subject to withholding or other trust fund payment requirements of the
Code or applicable state or local laws, such requirements may, at the discretion
of the Board or a duly authorized committee and to the extent permitted by the
terms of the Option and the then governing provisions of the Code and the
Exchange Act, be met (i) by the holder of the Option either delivering shares of
Stock or canceling Options or other rights to acquire Stock with a fair market
value equal to such requirements; (ii) by the Company withholding shares of
Stock subject to the Option with a fair market value equal to such requirements;
or (iii) by the Company making such withholding or other trust fund payment and
the Option holder reimbursing the Company such amount paid within 10 days after
written demand therefor from the Company.

        11. DILUTION OR OTHER ADJUSTMENT. In the event that the number of shares
of Stock of the Company from time to time issued and outstanding is increased
pursuant to a stock split or a stock dividend, the number of shares of Stock
then covered by each outstanding Option granted hereunder shall be increased
proportionately, with no increase in the total purchase price of the shares then
so covered, and the number of shares of Stock subject to the Plan shall be
increased by the same proportion. In the event that the number of shares of
Stock of the Company from time to time issued and outstanding is reduced by a
combination or consolidation of shares, the number of shares of Stock then
covered by each outstanding Option granted hereunder shall be reduced
proportionately, with no reduction in the total purchase price of the shares
then so covered, and the number of shares of Stock subject to the Plan shall be
reduced by the same proportion. In the event that the Company should transfer
assets to another corporation and distribute the stock of such other

                                       3
<PAGE>   4

corporation without the surrender of Stock of the Company, and if such
distribution is not taxable as a dividend and no gain or loss is recognized by
reason of section 355 of the Code or any amendment or successor statute of like
tenor, then the total purchase price of the Stock then covered by each
outstanding Option shall be reduced by an amount that bears the same ratio to
the total purchase price then in effect as the market value of the stock
distributed in respect of a share of the Stock of the Company, immediately
following the distribution, bears to the aggregate of the market value at such
time of a share of the Stock of the Company plus the stock distributed in
respect thereof. In the event that the Company distributes the stock of a
subsidiary to its shareholders, makes a distribution of a major portion of its
assets, or otherwise distributes significant portion of the value of its issued
and outstanding Stock to its shareholders, the number of shares then subject to
each outstanding Option and the Plan, or the exercise price of each outstanding
Option, may be adjusted in the reasonable discretion of the Board or a duly
authorized committee. All such adjustments shall be made by the Board or duly
authorized committee, whose determination upon the same, absent demonstrable
error, shall be final and binding on all participants under the Plan. No
fractional shares shall be issued, and any fractional shares resulting from the
computations pursuant to this section shall be eliminated from the respective
Option. No adjustment shall be made for cash dividends, for the issuance of
additional shares of Stock for consideration approved by the Board, or for the
issuance to stockholders of rights to subscribe for additional Stock or other
securities.

        12. OPTIONS TO FOREIGN NATIONALS. The Board or a duly authorized
committee may, in order to fulfill the purposes of this Plan and without
amending the Plan, grant Options to foreign nationals or individuals residing in
foreign countries that contain provisions, restrictions, and limitations
different from those set forth in this Plan and the Options made to United
States residents in order to recognize differences among the countries in law,
tax policy, and custom. Such grants shall be made in an attempt to provide such
individuals with essentially the same benefits as contemplated by a grant to
United States residents under the terms of this Plan.

        13. ASSIGNMENT. No Option granted under this Plan shall be transferable
other than by will or the laws of descent and distribution or pursuant to a
qualified domestic relations order as defined in the Code. Except as permitted
by the foregoing, each Option granted under the Plan and the rights and
privileges thereby conferred shall not be transferred, assigned, pledged, or
hypothecated in any way (whether by operation of law or otherwise), and shall
not be subject to execution, attachment, or similar process. On any attempt to
transfer, assign, pledge, hypothecate, or otherwise dispose of the Option, or of
any right or privilege conferred thereby, contrary to the provisions thereof, or
on the levy of any attachment or similar process on such rights and privileges,
the Option and such rights and privileges shall immediately become null and
void.

        14. EFFECT OF TERMINATION OF EMPLOYMENT. In the event that any holder is
terminated or resigns from his or her position with the Company or a subsidiary
within six months of the grant of an award, any unexercised portion of such
Option shall immediately become null and void and such holder shall have no
further rights thereunder. In the event that any officer or employee of the
Company or a subsidiary is terminated at any time for, in the determination of
the Board or a duly authorized committee, gross negligence in the performance of
his or her duties, substantial failure to meet written standards established by
the Company for the performance of his or her duties,

                                       4
<PAGE>   5

criminal misconduct, or willful or gross misconduct in the performance of his or
her duties, the Board or a duly authorized committee may cancel any and all
rights such individual may have in the unexercised portion of any Option held at
the time of termination. The Board or a duly authorized committee may, at the
time of the grant of the Option, establish any other restrictions on the
exercise of such Option subsequent to the termination or resignation of any
individual that it deems appropriate. The foregoing paragraph shall not apply to
consultants who are issued options.

        15. LISTING AND REGISTRATION OF SHARES. Each Option shall be subject to
the requirement that if at any time the Board shall determine, in its sole
discretion, that it is necessary or desirable to list, register, or qualify the
shares covered thereby on any securities exchange or under any state or federal
law, or obtain the consent or approval of any governmental agency or regulatory
body as a condition of, or in connection with, the granting of such Option or
the issuance or purchase of shares thereunder, such Option may not be exercised
in whole or in part unless and until such listing, registration, consent, or
approval shall have been effected or obtained free of any conditions not
acceptable to the Board.

        16. EXPIRATION AND TERMINATION OF THE PLAN. The Plan may be abandoned or
terminated at any time by the Board or a duly authorized committee except with
respect to any Options then outstanding under the Plan. The Plan shall otherwise
terminate on the earlier of the date that is: (i) ten years after the date the
Plan is adopted by the Board; or (ii) ten years after the date the Plan is
approved by the shareholders of the Company.

        17. FORM OF OPTIONS. Options granted under the Plan shall be represented
by a written agreement which shall be executed by the Company and the holder and
which shall contain such terms and conditions as may be determined by the Board
or a duly authorized committee and permitted under the terms of this Plan.

        18. NO RIGHT OF EMPLOYMENT. Nothing contained in this Plan or any Option
awarded pursuant to this Plan shall be construed as conferring on a director,
officer, or employee any right to continue or remain as a director, officer, or
employee of the Company or its subsidiaries.

        19. AMENDMENT OF THE PLAN. This Plan may not be amended more than once
during any six month period, other than to comport with changes in the Code or
the Employee Retirement Income Security Act or the rules and regulations
promulgated thereunder. Subject to the foregoing and the limitations, the Board
or a duly authorized committee may modify and amend the Plan in any respect.

                                            Wasatch Pharmaceutical, Inc.

                                            By:/S/ Gary V. Heesch, President

ATTEST:

        The undersigned hereby attests to this Wasatch Pharmaceutical, Inc. 1996
Non-Qualified Stock Option Plan.

                                            Wasatch Pharmaceutical, Inc.

                                            By:/S/ David K. Giles, Secretary

                                       5

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