<PAGE>
                                                                   EXHIBIT 10.37

                             Cabletron Systems, Inc.

                                 August 3, 2001
David Kirkpatrick
292 Middle Road
Portsmouth, NH 03801

David:

We have agreed that the terms below will govern your relationship with Cabletron
going forward. If these terms are acceptable to you, please sign and return a
copy of this letter to me, at which point it will become a binding agreement
between you and Cabletron.

     1.   CURRENT SALARY. You will be paid your current base salary through
          Sept. 2, 2001.

     2.   TRANSFORMATION BONUS. You will be paid a transformation bonus of
          $100,000 on Aug. 3, 2001. Also on Aug. 3, 2001, you will receive your
          normal quarterly bonus of $55,000 for Q2 on Sept. 9.

     3.   APRISMA. Subject to Board approval, you will be appointed a senior
          executive of Aprisma. As a senior executive, you will be paid your
          current base salary and will be eligible for bonuses based upon the
          performance of Aprisma.

     4.   CONFIDENTIALITY. You agree not to disclose any material confidential
          information of the Company or its subsidiaries to any third parties
          under circumstances that one would reasonably expect to cause material
          harm to the Company or its subsidiaries.

     5.   ADDITIONAL COMPENSATION. We agree to pay you additional compensation
          equal to one year salary plus bonus. One-half of the Additional
          Compensation shall be paid on Aug. 3. The other half of the Additional
          Compensation will be paid to you on Jan 2, 2002; this amount shall be
          placed in an escrow account to be released on Jan. 2 unless you have
          materially breached the confidentiality provision set forth below. At
          such time as you cease to be an employee of the Company, you will be
          paid a lump sum based upon your unused vacation time at your current
          base salary. In addition, we will pay for your full health and medical
          benefits for one year (through Sept. 2, 2002) or so long as you are an
          employee of Aprisma, which ever is longer. As part of your severance,
          you will be entitled to retain your laptop and cellular phone. We will
          maintain your email account and telephone number for one year through
          Sept. 2, 2002.

     6.   STOCK OPTIONS. Your Cabletron stock options will be treated the same
          as other employees, that is, the vesting on you Cabletron stock
          options will be accelerated through Feb. 28, 2002 and you will receive
          Riverstone rainbow options using the same ratio used with respect to
          Cabletron stockholders. With respect to your Aprisma, Enterasys, and
          Riverstone stock options, the remaining restrictions that prevent the
          transfer of the shares issued on exercise of the options will be
          lifted as of Aug. 6. This will not affect the exercisability of the
          stock options.

     7.   EXISTING LOAN. For purposes of your existing loan from Cabletron dated
          June 15, 2002, as of Aug. 6 you will be deemed to satisfy the
          conditions for complete forgiveness of the loan. You will not be
          required to repay any portion of the loan as a result of sales of
          Cabletron, Riverstone or Enterasys shares either prior to or after the
          date of this letter agreement.

                                               Cabletron Systems, Inc.

          /s/ David Kirkpatrick                By: /s/ Piyush Patel
          --------------------------               -----------------------------
          David Kirkpatrick                        Piyush Patel
                                                   CEO and President