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                                                                   EXHIBIT 10.23

                     EFFICIENT NETWORKS RESELLER AGREEMENT

The terms contained herein, along with the attachments and exhibits constitute
an AGREEMENT ("Reseller Agreement" or "Agreement") made this 21st day of
November, 1999 between Efficient Networks, Inc., a Delaware corporation with its
principal place of business at 4201 Spring Valley Road, Suite 1200, Dallas,
Texas, U.S.A., and its subsidiaries (collectively "Efficient") and Cabletron
Systems, Inc., a Delaware corporation, with its principle place of business at
35 Industrial Way, Rochester, New Hampshire, U.S.A. ("Reseller" or "Cabletron"),
and effective as of the closing of the merger contemplated by the Agreement and
Plan of Reorganization made and entered into as of even date herewith, among
Efficient, Reseller, Fire Acquisition Corporation, a California corporation and
a wholly-owned subsidiary of Efficient and Flowpoint Corporation, Inc., a
California corporation and a wholly-owned subsidiary of Reseller ("Flowpoint")
(such date referred to herein as the "Effective Date").


1.  DEFINITIONS:

1.1.  End User shall mean the ultimate customer that purchases Products for its
      --------
      internal use from Reseller.

1.2.  Exhibits to this Agreement are:

      Exhibit A  Products
      Exhibit B  Technical Support Guidelines
      Exhibit C  Limited Exclusivity
      Exhibit D  Marketing Principles

1.3.  Intellectual Property Rights shall mean all patents, copyrights,
      ----------------------------
      trademarks, mask works and other intellectual property rights relating to
      a Product.

1.4.  Orders shall mean purchase orders for Products submitted to Efficient by
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      Reseller under the terms of this Agreement.

1.5.  Parties shall mean Efficient and Reseller.
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1.6.  Products shall mean those products set forth in Exhibit A to this
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      Agreement, together with any product introduced by Efficient during the
      term of this Agreement that enhances the functionality of, or replaces, a
      product set forth in Exhibit A.

1.7.  Product Specifications shall mean Efficient or Flowpoint's published
      ----------------------
      specifications for the Flowpoint product current on date Efficient accepts
      Reseller's Order and any additional specifications agreed to by the
      Parties in writing.

1.8.  Software shall mean software products and software or firmware
      --------
      incorporated in hardware Products.

1.9.  Territory - Unless otherwise specified or agreed by the Parties in
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      writing, the Territory is worldwide.

1.10. Warranty Period - Unless otherwise specified by Efficient or agreed by
      ---------------
      the Parties, the Warranty Period shall be the shorter of twelve (12)
      months from the date the Product is delivered to the End User or fifteen
      (15) months from the date the Product is shipped to Reseller.

2.  RELATIONSHIP:

2.1.  Appointment - Efficient appoints Reseller as a non-exclusive reseller of
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      Products to be sold under Efficient and Reseller brands to End Users
      within the Territory under the terms of this Agreement.

2.2.  Limited Exclusivity - The parties agree that the limited exclusivity
      -------------------
      provisions set forth in Exhibit C shall apply to this Agreement.

2.3.  Relationship Reviews - Efficient and Reseller will conduct reviews of
      --------------------
      their relationship and performance under this Agreement at least twice
      during each year following the Effective Date. These reviews will
      consider, among other things, new products, Product Specifications and
      pricing, and Reseller's Product forecasts, purchases and payments under
      this Agreement.

2.4.  Marketing Principles - The parties recognize the need to coordinate their
      --------------------
      efforts with respect to sales opportunities for the products. The parties
      agree that they shall act in good faith to follow their mutual intentions
      as set forth in the Marketing Principles attached hereto as Exhibit D, and
      further agree to abide by the issue resolution mechanisms set forth
      therein.

3.  PRODUCT BRANDING:

3.1   Existing Arrangements - Any Flowpoint product which Reseller, immediately
      ---------------------
      prior to the Effective Date, was reselling under a Reseller brand, may, at

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      Reseller's request, continue to be resold under such Reseller brand. For
      purposes of rebranding, upgraded and enhanced versions of Products
      rebranded prior to the Effective Date shall be deemed to be Products
      entitled to rebranding. Such Products shall continue to be rebranded
      substantially similarly to the way they were being rebranded prior to the
      Effective Date. Any changes to the rebranding specifications shall be
      agreed in writing by authorized representatives of each Party.

3.2   Rebranding of Additional Products - Provided that the parties agree to
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      minimum purchase volumes for a particular additional Product, Reseller may
      request that additional Products be rebranded to carry a Reseller brand.
      In the event that the parties are unable to agree on minimum purchase
      volumes, Reseller may require Efficient to rebrand such additional
      Products provided Reseller pays Efficient's fully-loaded cost to effect
      such rebranding.

3.3   Other Products - Except as provided in Sections 3.1 and 3.2, Reseller
      --------------
      agrees that all Products sold by Reseller hereunder shall bear the brand
      marking and other labeling provided by Efficient. Reseller shall not
      remove any such branding or labeling, nor shall Reseller add any Reseller
      (or other) branding or labeling to any Product without the prior written
      consent of Efficient.

4.  RESELLER RESPONSIBILITIES:

4.1.  Product Forecasts - On or before the Effective Date and during the first
      -----------------
      week of each calendar month after the Effective Date, Reseller shall
      provide Efficient with a forecast of Reseller's expected demand for each
      Product to be purchased and delivered during each month of the subsequent
      twelve (12) month period.

4.2.  Firm Orders - With respect to Products rebranded at Reseller's request,
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      the Product forecasts for the first two (2) months of each twelve (12)
      month period shall constitute firm Orders for Products under this
      Agreement that are subject to acceptance by Efficient and will be
      accompanied by a purchase order by such amount.

5. PRODUCTS AND PRICING:

5.1.  New Products - Products which constitute enhancements of or replacements
      ------------
      for products listed on Exhibit A shall be added to Exhibit A by a writing
      signed by the parties, and shall thereafter be deemed to be "Products" for
      purposes of this Agreement. The parties acknowledge that the term Products
      is intended to encompass only those products heretofore manufactured by
      Flowpoint and any enhancements thereto or replacements therefor. To the
      extent that the parties later agree to permit Reseller to sell any
      products which were heretofore manufactured by Efficient (or are hereafter
      developed by Efficient and do not fall within the definition of Products)
      the right to resell any such products shall be the subject of a separate
      written agreement between the parties.

5.2.  Withdrawal of Products - Efficient shall have the right to cease
      ----------------------
      production and withdraw any Product from Exhibit A, provided Efficient
      gives Reseller a written "Product Withdrawal Notice" at least ninety (90)
      days prior to the effective date of the withdrawal. Reseller may, within
      forty-five (45) days after receipt of a Product Withdrawal Notice, submit
      a single, non-cancelable "Last Buy" Order for the affected Product for
      delivery within the subsequent three (3) months. Efficient shall not be
      obligated to accept any Last Buy Order which exceeds fifty (50) percent of
      the Product units that Reseller ordered during the twelve (12) month
      period prior to the date of the relevant Product Withdrawal Notice.

5.3.  Software and Firmware - All Products consisting of Software and Software
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      incorporated in any Product shall not be sold but shall be provided to
      Reseller and its customers subject to a use license.

5.4.  Product Modifications - In the event Efficient intends to modify a Product
      ---------------------
      Specification affecting its form, fit, interoperability or function,
      Efficient shall notify Reseller of the modification in writing no later
      than ninety (90) days prior to the effective date of the modification.
      Based upon information from Reseller, Efficient will make reasonable
      efforts to mitigate the impact of any modification on Reseller, including
      consideration of changes to the modification and allowing Reseller to make
      a final purchase of the unmodified Products, provided that Efficient shall
      retain the sole right to make final decisions concerning the design of
      Products and Product Specifications, and that the Order for any final
      purchase of unmodified Products shall be placed at least thirty (30) days
      prior to the effective date of the modification for delivery within sixty
      (60) days.

5.5.  [Intentionally Left Blank]

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5.6.  Most Favored Pricing - During the term of this Agreement, Efficient will
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      extend to Cabletron the best price it offers to third parties, for the
      same or lower volume of Products.

5.7.  Price Changes - Upon the written request of either Party, made at least
      -------------
      sixty (60) days prior to any anniversary of the Effective Date, Parties
      shall meet to consider and negotiate in good faith requested changes in
      Product prices.

5.8.  Price Decreases - The Parties agree that Product prices may require
      ---------------
      adjustment from time to time to allow Reseller to remain competitive, and
      Efficient will consider in good faith any request by Reseller for a
      reduction in the price of any Product. In the event Efficient determines
      to lower the price of a Product, the price decrease shall apply to all
      Products on order by Reseller but not shipped as of the effective date of
      the decrease.

5.9.  Price Terms - Prices for all Products are F.O.B. the shipping dock of the
      -----------
      Efficient manufacturing or distribution facility, with Reseller fully
      responsible for all costs of transportation, insurance, taxes, customs
      duties, landing, storage and handling fees, and documents or certificates
      required for exportation or importation.

6. ORDERING & SHIPMENT:

6.1.  No Conflicting Terms - No additional or different terms on the face or
      --------------------
      reverse side of any purchase order or other written or oral communications
      between the Parties shall supercede or amend the terms of this Agreement,
      unless such terms are agreed upon in advance, set forth in writing and
      signed by an authorized representative of each Party.

6.2.  Issuance and Acceptance - Each Order shall be dated, and shall contain:
      -----------------------
      (i) a complete list of the Products to be purchased specifying quantity,
      type, description and price; (ii) shipment and delivery instructions;
      (iii) branding requirements, where applicable; and (iv) any special terms
      and conditions agreed to in writing by the Parties. Efficient agrees to
      receive Orders placed by Reseller via electronic document transfer,
      facsimile, or hard copy only. Verbal or telephone orders must be followed
      promptly by one of the transmission means described above. All Orders are
      subject to acceptance by Efficient, and Efficient may reject Orders in its
      reasonable discretion.

6.3.  Right to Reschedule - Reseller may reschedule the date of the shipment of
      -------------------
      any Order once without penalty provided that Efficient receives written
      notice at least thirty (30) days prior to the scheduled shipment date
      requesting shipment on a date within ninety (90) days after the original
      shipment date.

6.4.  Delivery Schedule - Efficient will endeavor to deliver all Products in
      -----------------
      accordance with the Product delivery date specified in the Reseller's
      Order as accepted by Efficient, provided that Efficient reserves the
      right, at its sole discretion, to make partial shipments. When Products or
      component parts are in short supply, or on an industry wide allocation,
      Efficient will allocate its available inventory and make deliveries on a
      basis Efficient deems equitable, in its sole discretion, and without
      liability to Reseller on account of the method of allocation chosen or its
      implementation.

6.5.  Quantities - [Intentionally Left Blank]
      ----------

6.6.  No Right of Return - Reseller shall have no right to return and Efficient
      ------------------
      shall have no obligation to repurchase Products sold under this Agreement.

6.7.  Carrier & Risk of Loss - Products will be shipped by the carrier
      ----------------------
      designated in writing by Reseller. In the absence of specific shipping
      instructions from Reseller, Efficient may designate the carrier. In no
      event, however, shall Efficient be liable for the shipment, nor shall the
      carrier be deemed to be an agent or representative of Efficient. Title to
      Products and risk of loss shall pass to Reseller upon Efficient's delivery
      to the designated carrier.

6.8.  Packing - Products shipped by Efficient will be packed and packaged
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      according to Efficient's then current packaging methods. Special packaging
      or packing requirements shall be quoted by Efficient and mutually agreed
      to in advance.

7. SOFTWARE LICENSE TERMS:

7.1.  License Grant - Efficient hereby grants Reseller a nontransferable,
      -------------
      nonexclusive license to use and distribute Software solely for use by End
      Users in and in connection with their use of Products.

7.2.  Protection of Software - Reseller agrees not to modify, decompile or
      ----------------------
      disassemble Software except as expressly permitted by applicable law and
      agrees not to lend, rent, lease, sublicense, or otherwise transfer
      Software in any form to any

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      person except in accordance with this Agreement. Reseller will use its
      best efforts to protect Software and any copies or portions thereof from
      unauthorized reproduction, publication, disclosure or distribution.

8.  PAYMENT:

8.1.  Payment Terms - Efficient's payment terms are net thirty (30) days from
      -------------
      the date of Efficient's invoice. Reseller shall promptly pay all invoices
      and amounts due and maintain satisfactory credit arrangements with
      Efficient. All payments shall be made in United States dollars.

8.2.  Delinquency - If Reseller is delinquent in payment, Efficient may refuse
      ----------
      to accept any new Orders, or may cancel or delay shipment on existing
      Orders. Efficient may also rescind Reseller's credit terms and demand
      payment on either a pre-paid or delivery basis. Unless there is a
      legitimate dispute concerning an invoice, interest will accrue on
      delinquent amounts at the lesser of the maximum rate permitted by law or
      one and one half percent (1 1/2 %) per month from the due date.

9.  WARRANTY TERMS:

9.1.  Product Warranty - Efficient warrants that Products purchased under this
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      Reseller Agreement will conform to the Product Specifications applicable
      as of the date of Reseller's Order throughout the Warranty Period.

9.2.  Repair or Replacement - Efficient shall use commercially reasonable
      ---------------------
      efforts to, at its option, repair, replace or issue a credit equal to the
      purchase price for Products that fail to meet the applicable Product
      Specifications during the Warranty Period.

9.3.  Return, Repair or Replacement Procedures - Reseller shall pay all
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      transportation charges for Products returned to Efficient under these
      product warranty terms, except that Efficient shall pay the transportation
      charges for return of any Product that failed within thirty (30) days of
      its initial use by an End User. Efficient will pay all transportation
      charges back to the Reseller or End User. In the event that no warranty
      repair or replacement is required, Efficient reserves the right to charge
      Reseller for the transportation incurred by Efficient in returning the
      Product.

9.4.  Warranty Disclaimer - EXCEPT AS EXPRESSLY PROVIDED HEREIN, NO OTHER
      -------------------
      WARRANTY, EXPRESS OR IMPLIED SHALL APPLY. EFFICIENT SPECIFICALLY DISCLAIMS
      ANY IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
      PURPOSE. NO REPRESENTATION OR WARRANTY, INCLUDING BUT NOT LIMITED TO
      STATEMENTS OF CAPACITY, SUITABILITY FOR USE OR PERFORMANCE, WHETHER MADE
      BY EFFICIENT PERSONNEL OR RESELLER PERSONNEL SHALL BE CONSIDERED A
      WARRANTY BY EFFICIENT, FOR ANY PURPOSE, OR GIVE RISE TO ANY LIABILITY OF
      EFFICIENT WHATSOEVER.

9.5.  Warranty Notice - All End Users shall be provided with a written notice of
      ---------------
      the foregoing Product Warranty and Warranty Disclaimer either in a
      contract or upon delivery of the Product. In the event that Reseller shall
      modify or supplement the foregoing Product Warranty, Reseller shall
      indemnify and hold Efficient harmless from all claims, damages and related
      expenses, including attorneys' fees, incurred by Efficient during or after
      the term of this Agreement as a result of any such modification.

10. SERVICE:

10.1. End User Support - Reseller shall provide all first and second level End
      ----------------
      User customer support for Products, as defined below, in the same manner
      Reseller provides similar support for other products. Efficient will
      provide third level support, according to the Technical Support Guidelines
      set forth in Exhibit B to this Agreement, solely to Reseller's designated
      engineering personnel who are trained in the technical operation of the
      Product. As used herein: (i) First Level Support shall mean the provision
      of general product information, configuration support, collection of
      technical problem identification information and screening of customer
      support requests; (ii) Second Level Support shall mean First Level Support
      plus problem isolation, defect determination and module or Product
      replacement, lab simulation, interoperability testing and action plan
      definition; and (iii) Third Level Support shall mean back-up technical
      support by telephone and, where appropriate, the provision of hardware and
      software "bug fixes" and work-arounds.

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10.2.  Reseller's Efforts - Reseller shall use its best effort to resolve End
       ------------------
       User support problem without Efficient's assistance and insure that all
       Product problems and technical inquiries are reported in a standard
       format. Reseller shall cooperate with Efficient in identification of "bug
       fixes" and work-arounds and the provision of Level Three Support.

10.3.  Technical Information and Training - Efficient will provide technical
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       information and up to ___ days of training for ___ individuals with
       regard to each Product to allow Reseller to provide Level One and Level
       Two Support. Unless otherwise agreed by the Parties, all training shall
       take place at Efficient's facility in Dallas, Texas. All costs and
       expenses of Reseller's personnel in attending Efficient training shall be
       borne by the Reseller.

10.4.  Additional Support - Efficient may agree to provide Reseller with
       -------------------
       additional maintenance services and support pursuant to a separate
       agreement between the Parties.

10.5.  Non-Warranty Repair - Non-warranty repair services for Products may be
       -------------------
       provided by Efficient at a designated Efficient facility on a time and
       materials basis under Efficient's then standard prices, terms and
       conditions. Reseller shall also be responsible for all associated freight
       and insurance charges.

11.  INTELLECTUAL PROPERTY:

11.1.  Ownership - Unless expressly stated, nothing in this Agreement shall
       ---------
       grant Reseller a license to use or any other right, title or interest in
       any Efficient Intellectual Property Right, and all such Intellectual
       Property Rights shall remain the exclusive property of Efficient.
       Reseller acknowledges that its unauthorized use or assertion of ownership
       of any Efficient Intellectual Property Right will cause Efficient or its
       Affiliates immediate and irreparable harm and shall entitle Efficient or
       its Affiliates to obtain injunctive relief.

12.  DURATION AND TERMINATION:

12.1.  Term - The initial term of this Reseller Agreement shall be the three (3)
       ----
       year period commencing on the Effective Date and terminating on the date
       exactly three (3) years after the Effective Date unless earlier
       terminated pursuant to the terms of this Agreement. This Agreement may be
       renewed for additional one (1) year periods upon the same terms and
       conditions as set forth herein upon the mutual written agreement of the
       parties.

12.2.  Termination for Cause - This Agreement may be terminated upon the
       ---------------------
       occurrence of any of the following events: (i) by Efficient, upon ten
       (10) days written notice, should Reseller fail to pay any sums due
       hereunder within twenty (20) days of the due date thereof; or (ii) by
       either Party should the other Party commit a material breach of any
       obligation under this Agreement not specifically set out in this Section
       or any other Agreement between the parties and fail to cure such material
       breach within thirty (30) days after written notice to the defaulting
       party (hereinafter the "Default Notice"); or (iii) by either party,
       immediately, upon the insolvency of the other party, the appointment of a
       liquidator, receiver, administrative receiver or administrator.

12.3.  Termination on Change of Control - Notwithstanding the provisions of
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       Section 18.4 (Assignment) of this Agreement, either party may, in its
       sole discretion, terminate this Agreement immediately upon a change of
       control of the other party; provided, however, that the election to
       terminate must be made within thirty (30) days of the time that the
       terminating party becomes aware of the change of control; and provided
       further that any such termination shall not be effective for ninety (90)
       days from the notice and that, during the ninety (90) day notice period,
       this Agreement will remain in full force and effect. This restriction in
       Exhibit C and D shall not apply to a person who acquires Reseller in a
       change of control but shall continue to apply to Reseller and its
       subsidiaries so long as Reseller and its subsidiaries continue using
       Reseller's brand name(s) or until they legally cease to exist.

12.4.  Effects of Termination - Upon any termination of this Agreement, Reseller
       ----------------------
       shall: (i) refrain from submitting additional Product Orders; (ii)
       promptly pay for any Products which Reseller has ordered but has not yet
       paid Efficient; and (iii) allow Efficient, at its discretion, to
       repurchase at the invoice price all or any portion of the Products in
       Reseller's inventory. Products to be repurchased must be unused, in new
       condition, and in Reseller's inventory (or in transit from Efficient) on
       the day this Reseller Agreement ends. Reseller shall pay all shipping
       charges for Products returned and for all Products rejected. If Efficient
       chooses not to repurchase products from Reseller, Reseller may sell such
       existing inventories to End Users.

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12.5.  Limits of Liability for Termination - In the event this Agreement is
       -----------------------------------
       terminated, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR COMPENSATION,
       REIMBURSEMENT OR DAMAGES ON ACCOUNT OF THE LOSS OF PROSPECTIVE PROFITS OR
       ANTICIPATED SALES, OR ON ACCOUNT OF EXPENDITURES, INVESTMENTS, LEASES OR
       COMMITMENTS IN CONNECTION WITH THE BUSINESS OR GOOD WILL OF EFFICIENT OR
       RESELLER, OR FOR ANY OTHER REASON RELATING TO OR ARISING FROM SUCH
       TERMINATION.

12.6.  Post Termination Support - The termination of this Agreement shall not
       ------------------------
       relieve Efficient of its Warranty obligations under Article 8 of this
       Agreement with regard to Products sold by Reseller to End Users prior to
       the date of termination, and Efficient shall continue to provide the
       technical support described Article 9 of this Agreement for one (1) year
       following the date of termination.

13.  CONFIDENTIAL AND PROPRIETARY INFORMATION:

13.1.  Disclosure of Information - It is expected that Efficient and Reseller
       -------------------------
       may each disclose to the other proprietary or confidential information.
       For purposes of the following, the Party disclosing the Confidential
       Information is the "Discloser" and the Party receiving the Confidential
       Information is the "Recipient".

13.2.  Confidential Information - "Confidential Information" shall mean any and
       ------------------------
       all information of the Discloser that is not generally known by others
       with whom it competes or does business, and any and all information,
       publicly known in whole or in part or not, which, if disclosed would
       assist in competition against Discloser. Confidential Information
       includes without limitation such information relating to: (i) the
       technical specifications of the Products; (ii) the development, research,
       testing, marketing and financial activities of the Discloser; (iii) the
       identity and special needs of the customers or suppliers of the
       Discloser; and (iv) the people and organizations with whom the Discloser
       has business relationships and those relationships.

13.3.  Ownership and Non-Disclosure - All Confidential Information acquired by
       ----------------------------
       Recipient or its employees or agents shall remain Discloser's exclusive
       property, and Recipient shall use its best efforts (which in any event
       shall not be less than the efforts Recipient takes to ensure the
       confidentiality of its own proprietary and other confidential
       information) to keep, and have its employees and agents keep, any and all
       such information and data confidential, and shall not copy or publish or
       disclose it to others, or authorize its employees, or agents or anyone
       else to copy, publish, or disclose it to others, without Discloser's
       prior written approval, and shall return such information and data to
       Discloser at its request. Recipient shall only use any Confidential
       Information in connection with its performance under this Agreement.

13.4.  Exception - The confidentiality provisions in this Section will not apply
       ---------
       to information which is or which becomes generally known to the public by
       publication or by any means other than a breach of duty on the part of
       the Reseller hereunder or is released by Efficient without restriction or
       is released pursuant to judicial or governmental decree.

13.5.  Post Termination - Except to the extent necessary to fulfill ongoing
       ----------------
       product support obligations or as otherwise provided herein, upon
       termination or expiration, the Reseller shall deliver to Efficient all
       material furnished by Efficient and pertaining to Products, which is then
       in the possession of Reseller, and shall not retain copies of the same.
       Except as provided herein, upon termination or expiration, Efficient
       shall deliver to Reseller all material furnished by Reseller, which is
       deemed confidential hereunder.

14.  INTELLECTUAL PROPERTY CLAIMS:

14.1.  Indemnification by Efficient - Efficient shall defend, at Efficient's
       ----------------------------
       expense, any claim brought against Reseller or End Users (a "Claim
       Defendant") alleging that any Efficient Product acquired or licensed
       under this Agreement infringes a U.S. patent, copyright, or mask work
       right (hereinafter a "Claim"). Efficient shall pay all costs and damages
       awarded or agreed to in settlement, provided that the Claim Defendant
       gave Efficient prompt written notice of the Claim, reasonable assistance
       and sole authority to defend or settle the Claim. Efficient shall obtain
       for the Claim Defendant, the right to continue using the Product, replace
       or modify the Product so it becomes non-infringing. If such remedies are
       not reasonably available, Efficient shall grant Reseller

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       a credit for the Product normally depreciated and have Reseller return
       the Product to Efficient. Efficient shall not have any liability if the
       alleged infringement is based upon the use, license or sale of the
       Product in combination with other products, including software not
       furnished by Efficient. This is Efficient's entire liability and
       Reseller's exclusive remedy for intellectual property Claims.

14.2.  Representation and Indemnification by Reseller - Reseller represents and
       ----------------------------------------------
       warrants that it is the owner or licensee of all Reseller brands and
       agrees that Efficient shall have no responsibility for the protection or
       maintenance of Reseller's rights in Reseller brands. Reseller shall hold
       Efficient harmless from and defend, at Reseller's expense, any claim
       brought against Efficient alleging that any Reseller brand infringes the
       trademark, trade name or any other intellectual property right of a third
       party (a "Brand Claim"). Reseller shall pay all costs and damages awarded
       or agreed to in settlement, provided that the Efficient gave Reseller
       prompt written notice of the Brand Claim, reasonable assistance and sole
       authority to defend or settle the Brand Claim.

15.  LIMITATION OF LIABILITY:

15.1.  Limitation of Liability - IN NO EVENT SHALL EITHER PARTY OR ITS
       -----------------------
       RESPECTIVE AFFILIATES, OFFICERS, DIRECTORS, AGENTS, OR EMPLOYEES BE
       LIABLE TO RESELLER OR END USERS FOR ANY INDIRECT, INCIDENTAL, OR
       CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOSS OF DATA OR
       PROFITS OR ATTORNEY'S FEES, WHETHER CLAIMED BY REASON OF BREACH OF
       WARRANTY, IN TORT OR OTHERWISE, AND WITHOUT REGARD TO THE FORM OF ACTION
       IN WHICH SUCH CLAIM IS MADE. IN ANY EVENT, EACH PARTY'S LIABILITY SHALL
       BE LIMITED TO ONE MILLION UNITED STATES DOLLARS ($1,000,000) OR THE
       EQUIVALENT IN FOREIGN CURRENCY; PROVIDED, HOWEVER, THAT THIS LIMITATION
       SHALL NOT APPLY TO RESELLER'S OBLIGATION TO PAY FOR PRODUCTS PURCHASED
       HEREUNDER.

16.  DISPUTE RESOLUTION:

16.1.  Consultation and Review - The Parties shall make good faith efforts to
       -----------------------
       resolve all disputes arising under this Agreement through consultations.
       If consultations are unsuccessful in resolving any dispute, either Party
       may request a senior management review. Within ten (10) business days of
       any such request, designated vice presidents of Efficient and Reseller
       will meet in a mutually acceptable fashion to exchange relevant
       information and attempt to resolve the dispute.

17.  TRANSACTION RELATED ITEMS:

17.1.  Merger Agreement.  Reseller and Efficient have entered into an Agreement
       -----------------
       and Plan of Merger and Reorganization, dated as of November 21, 1999 (the
       "Merger Agreement").

17.2.  Indemnity Obligation.  Under the Merger Agreement Reseller has agreed to,
       --------------------
       under certain circumstances, indemnify and hold Efficient harmless from
       certain claims. Reseller and Efficient agree and acknowledge that nothing
       express or implied in this Agreement (e.g. Article 14) shall limit or
       modify any of Reseller's obligations under the Merger Agreement.

18.  GENERAL TERMS:

18.1.  Commercial Use - Products are manufactured by Efficient for standard
       --------------
       commercial use and are accepted and approved by Efficient following
       qualified test procedures, processes and programs established by
       Efficient prior to delivery to Reseller. Special acceptance criteria
       established by Reseller shall be deemed by Efficient as a request for
       custom Product and will be quoted on a case by case basis. Efficient
       shall not be responsible for any damages caused by Products which are not
       intended for use in critical safety systems or nuclear facilities.

18.2.  Import and Export - Certain Products may be subject to export or import
       -----------------
       control laws and regulations of the U.S. government and other
       governments. Reseller assures that Reseller and Resellers will comply
       with those regulations at their expense whenever they export or re-export
       controlled products or technical data obtained from Efficient or any
       product produced directly from the controlled technical data. Reseller
       shall hold harmless and indemnify Efficient from any damages, including
       attorneys' fees, and any government sanctions resulting to Efficient from
       a breach of this Section.

18.3.  United States Government Restricted Rights - All Software shall be
       ------------------------------------------
       licensed to End Users subject to

                                                                          Page 7
<PAGE>

       the following: "The enclosed Product (a) was developed solely at private
       expense; (b) contains "restricted computer software" submitted with
       restricted rights in accordance with section 52.227-19 (a) through (d) of
       the Commercial Computer Software-Restricted Rights Clause and its
       successors, and (c) in all respects is proprietary data belonging to
       Efficient and/or its suppliers. For Department of Defense units, the
       Product is considered commercial computer software in accordance with
       DFARS section 227.7202-3 and its successors, and use, duplication, or
       disclosure by the government is subject to restrictions set forth
       herein."

18.4.  Assignment - This Agreement may not be assigned or transferred in whole
       ----------
       or in part by Reseller without the prior written consent of Efficient.
       Subject to each party's right to terminate this Agreement as provided in
       Section 12.3, either party may, however, assign this Agreement without
       the other party's consent to any person or entity that acquires
       substantially all of the stock, assets or any major division, unit, or
       subsidiary of the assigning party.

18.5.  Waiver and Severability - A Party's failure to enforce any provision of
       -----------------------
       this Agreement shall not be deemed a waiver of that or any other
       provision of this Agreement. If any provision of this Agreement has been
       declared illegal, invalid or unenforceable, the provision shall be
       construed to be enforceable to the maximum extent permitted and, if not,
       shall be deemed deleted from this Agreement, provided that if such
       construction or deletion substantially alters the commercial basis of
       this Agreement, the Parties shall negotiate in good faith to amend the
       provisions of this Agreement to give effect to their original intent.

18.6.  Force Majeure - Except in the case of Reseller's failure to pay any
       -------------
       amounts due hereunder, neither Party shall be liable for any damages or
       penalties for delay in delivery nor for failure to give notice when such
       delay is due to the elements, acts of God, acts of the other Party, acts
       of civil or military authority, fires, or floods, epidemics, quarantine
       restrictions, war, riots, strikes, lockouts or other labor disputes,
       delays in transportation, delays in delivery by vendors, or any other
       causes, without limitation, which are beyond the reasonable control of
       the delayed Party. The delivery date shall be considered extended by a
       period of time equal to the time lost because of any delay that is
       excusable under this provision.

18.7.  Survival - Appropriate provisions of this Agreement, including but not
       --------
       limited to the following, shall survive the expiration or termination of
       this Agreement: Definitions; Ordering and Shipment; Software Terms;
       Payment; Warranty Terms; Intellectual Property; Duration and Termination;
       Confidential and Proprietary Information; Limitation of Liability; Import
       and Export; Confidentiality of Agreement, Waiver and Severability and
       Laws.

18.8.  Laws -This Reseller Agreement shall be governed by the laws of the State
       ----
       of Texas, U.S.A., regardless of the laws that might otherwise govern
       under applicable conflicts and choice of laws principles. Any Action
       under this Agreement must be brought within twelve (12) months after the
       cause of action arises.

18.9.  Relationship of the Parties - Except as expressly provided in this
       ---------------------------
       Agreement, Reseller shall not be, and will not hold itself out as, the
       representative, agent, commission-sales agent, franchisee or employee of
       Efficient for any purpose. This Agreement creates no relationship of
       joint venture, franchise or partnership, and neither Party has any right
       or authority to assume or to create any obligation or responsibility on
       behalf of the other Party. All agreements relating to the sale of the
       Products and Services provided by Reseller to its customers are
       Reseller's exclusive responsibility. Reseller shall indemnify against and
       hold Efficient harmless from, any and all claims, damages or legal
       proceedings and associated costs of whatever nature, relating to the
       performance by Reseller of this Agreement arising out of the acts or
       omissions of Reseller, its employees, servants, Resellers or agents.

18.10. Entire Agreement - This Reseller Agreement, its Exhibits and
       ----------------
       attachments, including all documents which are incorporated by reference,
       constitute the entire and only understanding between the Parties with
       regard to the subject matter hereof and thereof. Unless otherwise
       provided herein, no modifications to this Agreement shall be binding on
       either Party unless made in writing and signed by duly authorized
       representatives of both Parties. In the event of any conflict between
       this Agreement, and any Addendum, Exhibits, or other attachments, the
       terms of this Agreement shall govern.

18.11. Third-Party Financing - In the event Reseller obtains financing in any
       ---------------------
       form whatsoever for the

                                                                          Page 8
<PAGE>

        purchase of Products under this Agreement and there is a conflict
        between the provisions of any such financing agreement and this
        Agreement, the terms of this Reseller Agreement (other than Payment)
        shall govern.

18.12.  Notices - Where electronic communication is available, Efficient and
        -------
        Reseller may communicate with each other by electronic means. Efficient
        and Reseller agree that when electronic communications are used, they
        are the equivalent of written and signed documents except for Notices
        given under this Agreement which if transmitted electronically, shall
        also be sent via facsimile transmission (with a copy by U.S. mail or
        overnight courier (signature required)). Notices shall be deemed
        effective upon receipt or refusal to accept delivery. Routine business
        communications shall not be deemed to be Notices. All such notices shall
        be in English and addressed as follows:

        If to Efficient:

        Efficient Networks, Inc.
        4201 Spring Valley Road, Suite 1200
        Dallas, Texas 75244
        Attention:  Jill Manning
        Facsimile Number:  972-991-8579

        If to Cabletron:

        Cabletron Systems, Inc.
        35 Industrial Way
        Rochester, NH
        Attention:  __________________________
        Facsimile Number: ____________________
<PAGE>

IN WITNESS WHEREOF, the Parties have caused this Reseller Agreement to be
executed by their duly authorized representatives.

Efficient Networks, Inc.                Cabletron Systems, Inc.

      /s/ JILL MANNING                        /s/ PIYUSH PATEL
By:  _______________________________    By:  __________________________________

        Jill Manning                            Piyush Patel
Name:  _____________________________    Name:  ________________________________

         Chief Financial Officer                President
Title:  ____________________________    Title  ________________________________

         December 17, 1999                      December 17, 1999
Date:  _____________________________    Date:  ________________________________
<PAGE>

                     EFFICIENT NETWORKS RESELLER AGREEMENT

                              Exhibit A - Products

-------------------------------------------------------------------------
Product No.               Description
-------------------------------------------------------------------------
FP128                     ISDN Router SSR - 105 SSR - 103
-------------------------------------------------------------------------
FP144                     IDSL Router
-------------------------------------------------------------------------
FP2025                    ATM25 Router
-------------------------------------------------------------------------
FP2200                    SDSL Router
-------------------------------------------------------------------------
FP2200V                   SDSL IAD
-------------------------------------------------------------------------
SSR245                    Dual Ethernet Router
-------------------------------------------------------------------------
SSR250                    ADSL Router
-------------------------------------------------------------------------
SSR255                    ADSL Router
-------------------------------------------------------------------------
<PAGE>

                     EFFICIENT NETWORKS RESELLER AGREEMENT

                    Exhibit B - Technical Support Guidelines

Nature of Technical Support - During the term of this Agreement, Efficient will
assist Reseller in the identification and resolution of Product performance
problems and errors.  Efficient's technical support shall be Level 3 Support to
the Reseller in connection with its support of its Resellers and End Users.
Level 1 Support and Level 2 Support shall be the sole and exclusive
responsibility of the Reseller and its resellers.  Level 3 Support shall be
provided by Efficient only to engineering personnel designated by the Reseller
who are trained in the technical operation of the Product.  Efficient's support
will be provided in accordance with the following guidelines:

I.   Technical Support

     1.   Availability - Efficient shall provide Level 3 Support via telephone,
          ------------
          facsimile and electronic mail twenty-four hours per day, seven days
          per week.

     2.   Response - Reseller shall use reasonable efforts to attempt to resolve
          --------
          End User support requirements for the Products. If Reseller cannot
          successfully resolve an issue within a reasonable period of time,
          Efficient's technical support staff will provide assistance. Efficient
          will provide an initial response to all Reseller support requests
          within two (2) hours, and Reseller and Efficient will mutually agree,
          in good faith, what additional information or documentation will be
          required for resolution of the problem. Efficient will provide a
          problem report form for Reseller's use in reporting problems.

II.  Error Correction

     1.   Error Definitions - "Error" means a reproducible that causes a Product
          -----------------
          not to function substantially in conformance with its specifications.
          Errors are classified as follows:

          Category 1: End User's network segment or management application is
          down or experiencing a consistent, measurable performance impact with
          no immediate resolution available.

          Category 2: End User is experiencing intermittent failure, performance
          degradation, or functionality of network or management applications.

          Category 3: Issues that do not affect customer's normal network or
          management application operation or questions concerning Product
          functionality or usage.

      2.  Non-Emergency Technical Support - For End User or Reseller problems
          -------------------------------
          not deemed by Reseller to be an emergency, Efficient will use its best
          efforts to address and resolve the problems as quickly as practicable
          during normal business hours. If a particular problem is not resolved
          within two (2) business days following the initial call to Efficient,
          technical support managers and engineers for each Party, will discuss
          and work in good faith to devise and implement a satisfactory
          resolution. Problems regarded as non-emergencies include: (i)
          installation and operation problems, i.e., routine questions that can
          be resolved by following documentation; and (ii) deviations from
          documentation, omissions and known workarounds, i.e. problems that
          cannot be resolved by following the documentation or result from
          reasonable misinterpretation of the documentation.

      3.  Emergency Technical Support - Efficient acknowledges that Category 1
          ---------------------------
          and Category 2 Errors should be resolved quickly. During the
          applicable Warranty Period, Efficient shall replace any defective
          Products or correct Errors promptly following receipt of notice from
          Reseller, not to exceed the following:

          .  Efficient shall provide an initial response to Errors reported by
             Reseller during normal business hours within four (4) hours and
             Reseller and Efficient shall promptly agree in good faith to any
             additional information and documentation that may be required to
             permit Efficient to resolve such errors. The error
<PAGE>

             correction period begins after Reseller has enough information to
             profile the error and can recreate the error or has access to a
             facility where the error can be recreated.

          .  Efficient shall use its best efforts to resolve Category 1 Errors
             within two (2) working days of receipt of notice of such Error.

          .  Efficient shall use its best efforts to resolve Category 2 Errors
             within five (5) working days of receipt of notice of such Error.

          .  Efficient shall use its best efforts to resolve Category 3 Errors
             within fifteen (15) working days of receipt of notice of such
             Error.

          The prescribed Error correction periods above may be extended by
          agreement of the Parties, e.g., if resolution of problem requires
          hardware certification or test, or if resolution represents
          significant risk to the primary Product functions.

      4.  Support Reports and Evaluation - Efficient shall provide a reporting
          ------------------------------
          mechanism by which Reseller will regularly receive a detailed list of
          the status of all Errors reported and resolved, including a list of
          workarounds and bug-fixes. At least once during each calendar quarter,
          the Parties shall hold management-level meetings to discuss
          improvements in support.

III.  Technical Support Hotline

Reseller shall make all requests for technical support to the following hotline
telephone or facsimile number, or via the Internet to the address indicated:

     Efficient Technical Hotline contacts as follows:

     Telephone No. __________________________
     Facsimile No. ___________________________
     Electronic Mail: ___________@______.com

Efficient may change contact telephone numbers, facsimile numbers, or Internet
addresses on ten day's notice.
<PAGE>

                     EFFICIENT NETWORKS RESELLER AGREEMENT

                        Exhibit C - Limited Exclusivity

I.        Reseller Non Exclusive Reseller - Reseller's appointment by Efficient
          -------------------------------
          as a Reseller under the Reseller Agreement is on a non-exclusive
          basis. Efficient may appoint additional parties to sell Products and
          may sell Products itself to all parties throughout the Territory.

II.       Efficient Exclusive Supplier - Reseller agrees that it shall acquire
          DSL and ISDN customer premises equipment ("CPE") for resale from
          Efficient as provided herein.

          .  First Twelve Months - Reseller agrees that, for a period of twelve
             (12) months from the Effective Date, it shall purchase for resale
             CPE exclusively from Efficient. Reseller shall be relieved of this
             obligation, and may purchase CPE for resale from other parties, in
             the event that: (A) Efficient is unable to meet Reseller's
             reasonable delivery requirements for CPE; or (B) Efficient CPE does
             not substantially meet the specifications of Reseller or Reseller's
             customer for the CPE and, after reasonable notice, Efficient is
             unable or unwilling to modify its products to meet Reseller or the
             customer requirements in the required timeframe; or (C) a third
             party manufacturer of CPE is able to supply comparable CPE to
             Reseller at prices which are equal to or less than ninety-five
             percent (95%) of the price at which Efficient is offering
             comparable CPE to Reseller; or (D) Reseller's customer makes a
             specific request not solicited by Reseller for CPE manufactured by
             a third party. Any exception to the general rule of exclusivity
             will apply to the specific product or order presented by Reseller,
             but will not result in a general release from the foregoing
             exclusivity provisions.

          .  Subsequent Periods - Following the initial twelve month period of
             the Reseller Agreement and for so long as the Reseller Agreement
             remains in effect, Reseller agrees that Efficient shall be its
             preferred supplier of CPE for resale and that Reseller shall
             feature Efficient CPE as its lead CPE products.

III.      Branding - For so long as the Reseller Agreement remains in effect,
          --------
          Reseller agrees that it will not rebrand any CPE as Reseller CPE,
          other than (i) CPE so branded by Efficient pursuant to the Reseller
          Agreement and (ii) CPE purchased from third parties as permitted by
          paragraph II. To the extent that Reseller acquires a third party which
          makes or sells CPE that is comparable to the Flowpoint CPE, Reseller
          will not rebrand any such CPE as Reseller CPE for the longer of (A)
          twelve (12) months from the date it acquires such third party; or (B)
          that date on which it otherwise generally ceases to use the branding
          of the acquired entity.

IV.       Sales Force Training and Incentives - Reseller agrees that, for so
          long as the Reseller Agreement remains in effect:

          .  Reseller shall provide Efficient with access to its sales personnel
             on a regular basis in conjunction with regularly scheduled Reseller
             sales force training events so that Efficient may provide training
             on the Flowpoint CPE;

          .  Reseller shall not permit any third party CPE manufacturer to offer
             similar training to Reseller sales personnel; provided, however,
             that Reseller may permit third party manufacturers supplying CPE as
             permitted by paragraph II to conduct limited training as reasonably
             required;

          .  Reseller shall utilize marketing material provided by Efficient, or
             jointly developed by Reseller and Efficient, as its exclusive
             marketing material relating to CPE except with respect to third
             party CPE permitted by paragraph II above;

          .  To the extent that Reseller elects to feature CPE at trade shows or
             in general product marketing material, it shall feature Flowpoint
             CPE substantially more predominantly at such shows or in such
             material than it features any other third party CPE;

          .  Reseller shall include in Flowpoint CPE its product/commission
             lists made available to its sales personnel and shall pay customary
             commissions to its sales personnel on sales of Flowpoint CPE;
<PAGE>

          .  Reseller shall not compensate (through commissions, rebates,
             special incentives or any other means) its sales personnel for the
             sale of third party CPE at rates more favorable than the rates at
             which Reseller compensates its sales personnel for sales of
             Flowpoint CPE; and

          .  Reseller shall not disseminate any press releases or similar
             announcements relating to any non-Efficient CPE which Reseller may
             sell nor with respect to any strategic relationship, joint or
             cooperative marketing or similar arrangement with any third-party
             supplier of CPE.
<PAGE>

                     EFFICIENT NETWORKS RESELLER AGREEMENT

                        Exhibit D - Marketing Principles

These Marketing Principles set forth the intentions of the parties as it relates
to opportunities which may arise to sell DSL and ISDN customer premises
equipment (DSL and ISDN customer premises equipment are referred to herein as
"CPE.").  In particular, the parties recognize that situations are likely to
arise where the sales force of each party may be presented with the same
business opportunity, or different opportunities within a single customer
enterprise.  It is the parties intention that any such conflicts be resolved
through good faith discussions between the parties taking into account the
guidelines set forth herein.

I.        General Statement - Efficient is primarily in the business of
          -----------------
          developing and selling CPE. Reseller is not primarily in the business
          of developing or selling CPE, and intends to sell CPE only in
          situations which may lead to sales by Reseller of other Reseller
          products and services. It is the general intention and marketing
          strategy of the parties that: (1) sales which primarily involve CPE
          will be handled by Efficient and (2) sales which primarily involve
          non-CPE Reseller products and services will be handled by Reseller. It
          is the mutual goal of the parties to increase the level of CPE being
          sold through all available sales channels and to optimize the use of
          their respective sales resources.

II.       Specific Accounts - In furtherance of the General Statement, the
          -----------------
          parties acknowledge that there are certain customers which require a
          more specific statement of intention. These are as set forth in this
          Article II.

         1.  Efficient Key Accounts - Efficient has existing customer
             ----------------------
             relationships with each of the following parties and/or their
             purchasing affiliates (the "Efficient Key Accounts"): America
             Online; Concentric Networks; Covad Communications; Northpoint;
             Rhythms; and SBC. The parties agree that Efficient will be the
             preferred vendor of CPE into these accounts. Absent unusual
             circumstances, Reseller will refrain from selling CPE into these
             accounts, and will refer sales leads to Efficient.

         2.  Common Key Accounts - Efficient and Reseller each have existing
             -------------------
             customer relationships with the following parties and/or their
             purchasing affiliates (the "Common Key Accounts"): AT&T; Bell
             Atlantic; Bell South; Mindspring; and MCI/Worldcom. Both Efficient
             and Reseller expect to continue to sell their respective products
             and services into each of the Common Key Accounts. In order to
             mitigate the potential for the inefficient duplication of sales
             efforts with respect to the Common Key Accounts, promptly following
             the Effective Date, representatives of Efficient and Reseller shall
             meet and (1) inform the other party about the status of current and
             prospective sales activities in each of the Common Key Accounts;
             and (2) work in good faith to develop a plan of action to mitigate
             any duplications of effort or other inefficiencies which may then
             exist or may arise in the future. Efficient and Reseller further
             agree that, for so long as the Reseller Agreement remains in
             effect, they will keep the other party informed of current and
             prospective sales activities in the Common Key Accounts and will
             meet periodically to discuss any issues that may have arisen.

         3.  Other Accounts - Efficient and Reseller recognize that they are
             --------------
             likely to engage in selling activities with respect to customers or
             potential customers that are not Efficient Key Accounts or Common
             Key Accounts. As to all such other customers or potential
             customers, it is the intention that the General Statement shall
             apply.

III.      Contacts and Dispute Resolution - The parties agree to appoint primary
          -------------------------------
          contact persons and to attempt to resolve in good faith any issues
          that may arise under these Marketing Principles.

         1.  Contacts - The following persons shall be the initial contacts for
             --------
             resolving any issues under these Marketing Principles: for
             Efficient, David Stefan; for Reseller, Romulus Pereira; for
             Flowpoint, Dano Ybarra. Although the parties are free to change
             their contact person in their discretion by notice to the other
             parties, each party acknowledges and agrees that maintaining
             continuity of the contacts and relationship will be beneficial to
             all parties, and will make decisions to keep or change contact
             persons with this in mind.
<PAGE>

         2.  Dispute Resolution - Each party shall put into place appropriate
             ------------------
             mechanisms such that conflicts that arise among their respective
             sales forces will be brought to the attention to their contact
             persons. In the event of any such dispute, the contact persons
             shall promptly meet (in person or by phone) and shall attempt in
             good faith to resolve any such controversies following the
             principles set forth in these Marketing Principles. If, after
             making reasonable efforts to resolve the controversy, the contact
             persons are unable to arrive at a mutually satisfactory resolution,
             the matter shall be elevated to the second level contacts within
             the organizations. The second level contacts shall be: for
             Efficient, [Mark Floyd]; for Reseller, [________________]; and for
             Flowpoint, [Chuck Waggoner]. Each party is free to designate a
             different second level contact. The second level contacts shall
             attempt to resolve any controversies in the same manner as the
             initial contacts act under these Marketing Principles.