Document:

<PAGE>

                                                                    Exhibit 10.7

                             ASSIGNMENT AGREEMENT

     THIS ASSIGNMENT AGREEMENT (this " Agreement") is entered into as of
August 29, 2000, among SILVER LAKE PARTNERS, L.P .("Silver Lake") (the
"Assignor"), MORGAN STANLEY DEAN WITTER EQUITY FUNDING, INC. (the "MS
Assignee"), SILVER LAKE INVESTORS, L.P. and SIL VER LAKE TECHNOLOGY INVESTORS,
L.L.C. (collectively , the "SL Assignees"), INTEGRAL CAPITAL PARTNERS V, L.P.
and INTEGRAL CAPITAL PARTNERS V-MS SIDE FUND, L.P. (collectively, the "Integral
Assignees" and, together with the MS Assignee and the SL Assignees, the "
Assignees") and CABLETRON SYSTEMS, INC. (the "Company").

                                   RECITALS

     WHEREAS, the Assignor has entered into a Securities Purchase Agreement,
dated as of July 26, 2000, with the Company (the "Purchase Agreement");
capitalized terms used and not otherwise defined herein shall have the meanings
ascribed to them in the Purchase Agreement;

     WHEREAS, each of the Assignees desires to become an "Investor" under the
Purchase Agreement with respect to the purchase of those Shares, Parent
Warrants, Subsidiary Stock Purchase Rights and IPO Valuation Warrants (if any)
set forth under such Assignee's name on Schedule A hereto, as well as any
Replacement Warrants issuable under the Purchase Agreement in respect of such
Subsidiary Stock Purchase Rights and any Subsidiary Warrants issuable under the
Purchase Agreement in respect of such Parent Warrants and Replacement Warrants
(with respect to each such Assignee, collectively, its " Assigned Securities");

     WHEREAS, pursuant to its rights under Section 9.4 of the Purchase
Agreement, the Assignor desires to assign to each of the Assignees the
Assignor's rights and obligations under the Purchase Agreement with respect to
the purchase of such Assignee's Assigned Securities, and to cause such Assignee
to become an "Investor" under the Purchase Agreement with respect to such
Assigned Securities and a party to the Purchase Agreement;

     NOW, THEREFORE, in consideration of the foregoing recitals and the mutual
promises hereinafter set forth, the parties hereto agree as follows:

     SECTION I. Assignment and Assumption. The Assignor hereby assigns to each
Assignee the Assignor's rights and obligations under the Purchase Agreement with
respect to the purchase of such Assignee's Assigned Securities, and such
Assignee hereby assumes such rights and obligations under the Purchase Agreement
(severally and not jointly with the other Assignees), hereby becomes an
"Investor" under the Purchase Agreement with respect to its Assigned Securities
and a party to the Purchase Agreement, and hereby agrees to pay its portion of
the Purchase Price as required under the Purchase Agreement with respect to the
purchase of its Assigned Securities ( each Assignee's portion of the Purchase
Price to be paid at the Closing, as set forth under such Assignee's
<PAGE>

name on Schedule A hereto, its " Assignee Purchase Price") and to comply with
the other covenants and agreements of an Investor under the Purchase Agreement
and the other Transaction Documents. The Company and each of the other parties
hereto hereby agrees that, notwithstanding anything to the contrary contained in
the Purchase Agreement or any of the other Transaction Documents, the MS
Assignee shall be permitted (without the consent of any other Person), to
transfer any or all of its Assigned Securities to a collective investment
vehicle for which PG Investors III, Inc. is the sole general partner or sole
managing member, as applicable (each, a "PG Fund") at any time prior to or
following the Closing, subject to such PG Fund having agreed to be bound by the
terms and conditions of the Purchase Agreement and each of the other Transaction
Documents applicable to an "Investor" thereunder (including without limitation
such PG Fund having made the representations and warranties of an "Investor"
thereunder) in a form reasonably acceptable to the Company and to the Assignor
(and such agreement shall constitute a waiver of any restrictions to the
contrary contained in the Purchase Agreement or any of the other Transaction
Documents).

     SECTION 2. Closing Payments. Not later than two business days prior to the
Closing, the Company will notify each of the Assignees in writing or by
electronic mail of the bank account(s) to which such Assignee's Assignee
Purchase Price is to be wired at the Closing.

     SECTION 3. Amendment of Purchase Agreement. Each Assignee acknowledges
that, pursuant to Section 9.7 of the Purchase Agreement, the Purchase Agreement
may be amended upon the written consent of the Company and the Majority
Investors, and such Assignee further acknowledges that the Company and the
Majority Investors intend to amend the Purchase Agreement prior to the Closing
in the manner contemplated by Section 1.4(f) of the Purchase Agreement.

     SECTION 4. Representations and Warranties. Each of the Assignees hereby
makes each of the representations and warranties contained in Article IV of the
Purchase Agreement (severally with respect solely to itself, and not jointly
with the other Assignees) to the Company and the Assignor as of the date hereof.
Each of the Assignees hereby acknowledges and agrees that it is purchasing its
Assigned Securities directly from the Company under the Purchase Agreement, and
not in any manner from the Assignor, and that the Assignor has made no
representations, warranties, covenants or agreements whatsoever to such Assignee
with respect to the value of, or other matters relating to, such Assigned
Securities (except for those covenants and agreements of the Assignor expressly
set forth in this Agreement). This Agreement shall constitute a "Transaction
Document" for purposes of the Purchase Agreement.

     SECTION 5. Entire Agreement: Supersedes Prior Agreements. This Agreement,
the Purchase Agreement and the other Transaction Documents (in each case
including all the exhibits and schedules hereto and thereto, and including any
written agreements entered into in connection therewith) constitute the full and
entire understanding and agreement among the parties hereto with regard to the
subjects hereof and thereof and no party shall be liable or bound to any other
in any manner by any representations, warranties, covenants and agreements
except as specifically set forth herein and therein. Other than the
representations, warranties, covenants and agreements set forth herein and in
the Purchase Agreement and the other Transaction Documents to which they are
parties

                                       2
<PAGE>

(in each case including all the exhibits and schedules hereto and thereto, and
including any written agreements entered into in connection therewith), none of
the parties hereto has made or is making any representation, warranty, covenant
or agreement, express or implied, with respect to the matters contained in this
Agreement, the Purchase Agreement and the other Transaction Documents, and no
promise or inducement for this Agreement, the Purchase Agreement or the other
Transaction Documents has been made by any party hereto, other than as set forth
in this Agreement, the Purchase Agreement and the other Transaction Documents to
which they are parties (in each case including all the exhibits and schedules
hereto and thereto, and including any written agreements entered into in
connection therewith). This Agreement is executed by each of the Assignees
freely and voluntarily, and without reliance upon any statement or
representation by the Company or the Assignor to the Assignees or any of their
Affiliates, attorneys or agents, except as set forth herein and in the Purchase
Agreement and the other Transaction Documents to which they are parties (in each
case including all the exhibits and schedules hereto and thereto, and including
any written agreements entered into in connection therewith).

     SECTION 6. Governing Law; Jurisdiction; Waiver of Jury Trial. This
Agreement shall be governed in all respects by the laws of the State of Delaware
exclusive of its conflict-of-law principles. The parties hereby submit to the
non-exclusive jurisdiction of the courts of the State of New York for the
purpose of any suit, proceeding or judgment with respect to this Agreement. Each
of the parties hereto hereby irrevocably and unconditionally waives trial by
jury in any legal action or proceeding in relation to this Agreement and for any
counterclaim therein.

     SECTION 7. Counterparts; Execution by Facsimile Signature. This Agreement
may be executed in any number of counterparts, each of which shall be an
original, but all of which together shall constitute one instrument. This
Agreement may be executed by facsimile signature(s).

     SECTION 8. Amendment and Waiver. This Agreement may be amended or modified,
and the rights of the parties hereto may only be waived, upon the written
consent of the Assignor and each of the Assignees to whom such amendment,
modification or waiver relates.

                                       3
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date set forth in the first paragraph hereof.

                                SILVER LAKE PARTNERS, L.P.

                                By: Silver Lake Technology Associates, L.L.C.,
                                    its general partner

                                By: /s/ James A. Davidson
                                    -----------------------------
                                    An Authorized Signatory

                                MORGAN STANLEY DEAN WITTER EQUITY FUNDING, INC.

                                By: /s/ Thomas A. Clayton
                                    -----------------------------
                                    Name: Thomas A. Clayton
                                    Title: Vice President

                                SILVER LAKE INVESTORS, L.P.

                                By: Silver Lake Technology Associates, L.L.C.,
                                    its general partner

                                By: /s/ James A. Davidson
                                    -----------------------------
                                    An Authorized Signatory

                                SILVER LAKE TECHNOLOGY INVESTORS, L.L.C.

                                By: Silver Lake Technology Associates, L.L.C.,
                                    its managing member

                                By: /s/ James A. Davidson
                                    -----------------------------
                                    An Authorized Signatory

                                       4
<PAGE>

                                INTEGRAL CAPITAL PARTNERS V, L.P.

                                By: Integral Capital Management
                                    L.L.C., its general partner
                                    -------------------------------

                                By: /s/ Pamela K. Hagenah
                                    -----------------------------
                                    Name: Pamela K. Hagenah
                                    Title: Manager

                                INTEGRAL CAPITAL PARTNERS V-MS
                                SIDE FUND, L.P.

                                By: ICP Management, L.L.C., its
                                    general partner
                                    -----------------------------

                                By: /s/ Pamela K. Hagenah
                                    -----------------------------
                                    Name: Pamela K. Hagenah
                                    Title: Manager

Agreed and Accepted:

CABLETRON SYSTEMS, INC.

By: /s/ Piyush Patel
    ------------------------------
    Name: Piyush Patel
    Title: Chief Executive Officer

                                       5<PAGE>

                                                                    Exhibit 10.8

                                FIRST AMENDMENT
                                      TO
              AMENDED AND RESTATED SECURITIES PURCHASE AGREEMENT,
                             STANDSTILL AGREEMENT
                                      AND
                         REGISTRATION RIGHTS AGREEMENT

     This First Amendment to Amended and Restated Securities Purchase Agreement,
Standstill Agreement and Registration Rights Agreement (this "Amendment") is
entered into as of July 12, 2001 by and between Cabletron Systems, Inc., a
Delaware corporation (the "Company"), Silver Lake Partners, L.P., a Delaware
limited partnership ("Silver Lake"), and the other Investors listed on the
signature page hereto.

     WHEREAS, the Company and Silver Lake are parties to an Amended and Restated
Securities Purchase Agreement, dated as of August 29, 2000 (the "Securities
Purchase Agreement"), a Standstill Agreement, dated as of August 29, 2000 (the
"Standstill Agreement"), and a Registration Rights Agreement, dated as of August
29, 2000 (the "Registration Rights Agreement");

     WHEREAS, the Company, Silver Lake and the other Investors desire to amend
certain terms of the Securities Purchase Agreement, the Standstill Agreement and
the Registration Rights Agreement as set forth herein;

     NOW, THEREFORE, in consideration of the mutual promises hereinafter set
forth, the parties hereto hereby agree as follows:

1.   Definitions.  Capitalized terms used and not otherwise defined herein shall
have the meanings set forth in the Securities Purchase Agreement.

2.   Amendment to Securities Purchase Agreement.

     2.1. Amendment to Section 1.5(c) of Securities Purchase Agreement.  Section
1.5(c) of the Securities Purchase Agreement is hereby amended and restated in
its entirety to read as follows:

     "(c)  The Replacement Warrants (i) will be immediately exercisable upon
     issuance (provided that they shall in any event become exercisable no later
     than immediately prior to the consummation of the triggering third-party
     acquisition, in the case of an event described in Section 1.5(a)(iii)
     above), and will remain exercisable until the later of (a) the fourth
     anniversary of the Closing or (b) the first anniversary of the consummation
     of the Purchase Right Flip-Up Event giving rise to the issuance of such
     Replacement Warrants, (ii) will have an initial aggregate exercise price
     equal to the product of (A) 5 2/3, multiplied by (B) the exercise price in

                                       1
<PAGE>

     effect for the related Callable Subsidiary Stock Purchase Rights
     immediately prior to such Purchase Right Flip-Up Event (subject to the
     following proviso), (iii) will initially be exercisable for that percentage
     of the Company's diluted Common Stock equal to the product of (A) that
     percentage of the diluted common stock of the Operating Subsidiary for
     which the related Subsidiary Stock Purchase Rights were (or when issued,
     would have been) exercisable immediately prior to the consummation of such
     Purchase Right Flip-Up Event multiplied by (B) a fraction the numerator of
     which is the Flip-Up Valuation and the denominator of which is the market
     capitalization of the Company immediately preceding such Purchase Right
     Flip-Up Event, and (iv) otherwise will be on the terms and conditions set
     forth in the form of Parent Warrant; provided, however, that, in the case
     of a Purchase Right Flip-Up Event described in clause (i) or clause (ii) of
     the definition thereof occurring prior to the second anniversary of the
     Closing, the initial aggregate exercise price of the Replacement Warrants
     shall be discounted, and shall equal the product of (A) 5 2/3, multiplied
     by (B) the exercise price in effect for the related Callable Subsidiary
     Stock Purchase Rights immediately prior to such Purchase Right Flip-Up
     Event, multiplied by (C) 0.9."

     2.2. Issuance of Subsidiary Warrants in Connection with Spin-Off.  The
parties acknowledge and agree that the Company intends to consummate a Spin-Off
of Riverstone (the "Riverstone Spin"). For the avoidance of doubt, the parties
further agree that the calculations set forth in the attached Exhibit A reflect
the proper application of Section 1.7 of the Securities Purchase Agreement in
connection with the Riverstone Spin, and, based on the assumptions set forth in
Exhibit A, (a) the exercise price per share of Common Stock under the Class A
Parent Warrants and the Class B Parent Warrants outstanding on the date of the
Riverstone Spin would be adjusted as set forth in the attached Exhibit A, and
(b) the Company would cause Riverstone to issue to the Investors Subsidiary
Warrants with respect to the Class A Parent Warrants and Class B Parent Warrants
exercisable for the number of shares of common stock of Riverstone, and the
exercise price per share, set forth in the attached Exhibit A. Subject to the
foregoing, such Subsidiary Warrants shall have such other terms as are described
in the Securities Purchase Agreement.

     2.3. Issuance of Replacement Warrants in Connection with Purchase Right
Flip-Up Event. The parties acknowledge and agree that the Company intends to
consummate a merger of Enterasys with and into the Company (the "Enterasys Flip-
Up Event") and that, in the event that the Riverstone Spin occurs within one
hundred and twenty days of the date hereof, the Riverstone Spin shall be deemed
to have occurred prior to the consummation of the Enterasys Flip-Up Event for
all purposes of the Securities Purchase Agreement and the issuance of
Replacement Warrants in connection with the Enterasys Flip-Up Event. The parties
further agree that, in the event that the Enterasys Flip-Up Event is consummated
within ninety days of the date hereof, pursuant to Section 1.5 of the Securities
Purchase Agreement (and notwithstanding anything in Section 1.5(c)(ii) or
1.5(c)(iii) to the contrary) in connection with the Enterasys Flip-Up Event, (a)
the Subsidiary Stock Purchase Rights issued to the Investors by Enterasys shall
be canceled, and (b) the Company shall issue to the Investors Replacement
Warrants exercisable for an aggregate of 7,400,000 shares of Common Stock, with
an aggregate exercise price of $45,880,000. Subject to the foregoing, such
Replacement Warrants shall have such other terms as are described in the
Securities Purchase Agreement.

                                       2
<PAGE>

     2.4. Further Notifications. The Company shall have no further obligation to
provide the Investors with notice of the Riverstone Spin or the Enterasys Flip-
Up Event, provided that the Company consummates each of the foregoing upon the
terms and within the time periods contemplated by this Amendment and its
Exhibits.

     2.5. References to the Company's Series A and Series B Participating
Convertible Preferred Stock.  Upon the consummation of the exchange by the
Company pursuant to a Securities Exchange Agreement among the parties hereto,
dated as of July 12, 2001, of the Company's Series D and Series E Participating
Convertible Preferred Stock for the outstanding shares of the Company's Series A
and Series B Participating Convertible Preferred Stock issued pursuant to the
Securities Purchase Agreement (the "Exchange"), (a) the references in Sections
5.5, 5.6, 6.1 and 9.4 of the Securities Purchase Agreement to the "Shares" shall
be deemed to be references to the Company's Series D and Series E Participating
Convertible Preferred Stock, and (b) the references in Section 5.7 of the
Securities Purchase Agreement to the "Shares" issued by the Company to the
Investors on the Closing Date shall be deemed to be references to the Company's
Series D and Series E Participating Convertible Preferred Stock, which shall be
deemed to have been outstanding as of the Closing Date for purposes of Section
5.7 of the Securities Purchase Agreement.

3.   Amendment to Standstill Agreement.  Upon the consummation of the Exchange,
Section 1.01(p) of the Standstill Agreement is hereby amended and restated in
its entirety to read as follows:

          "(p)  "Preferred Stock" shall mean the Company's Series D and
     Series E Participating Convertible Preferred Stock, $1.00 par value per
     share."

4.   Amendment to Registration Rights Agreement.  Upon the consummation of the
Exchange, references in the Registration Rights Agreement to the "Preferred
Stock" shall be deemed to be references to the Company's Series D and Series E
Participating Convertible Preferred Stock and shall be deemed to include any
preferred stock or other securities issued upon a recapitalization of the
Company's Series D and Series E Participating Convertible Preferred Stock,
except where the context requires otherwise.

5.  Miscellaneous.

     5.1. Full Force and Effect. Except to the extent specifically amended
hereby, the provisions of the Securities Purchase Agreement and the Standstill
Agreement shall remain unmodified, and each of the Securities Purchase Agreement
and the Standstill Agreement shall continue in full force and effect.

     5.2. Governing Law. This Amendment shall be governed in all respects by the
laws of the State of Delaware, exclusive of its conflict-of-law principles. The
Company hereby submits to the non-exclusive jurisdiction of the courts of the
State of New York, and the Investors hereby submit to the non-exclusive
jurisdiction of the courts of the State of New Hampshire, in each case for the
purpose of any suit, proceeding or judgment with respect to this Amendment. Each
of the parties hereto hereby irrevocably and unconditionally waives trial by
jury in any legal action or proceeding in relation to this Amendment and for any
counterclaim therein.

     5.3. Severability. In case any provision of this Amendment shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

     5.4. Amendment and Waiver. This Amendment may be amended or modified, and
the rights of the Company or the Investors hereunder may only be waived, upon
the written consent of the Company and the Majority Investors.

     5.5. Titles and Subtitles. The titles of the sections and subsections of
this Amendment are for convenience of reference only and are not to be
considered in construing this Amendment.

     5.6. Counterparts; Execution by Facsimile Signature.  This Amendment may be
executed in any number of counterparts, each of which shall be an original, but
all of which together shall constitute one instrument.  This Amendment may be
executed by facsimile signature(s).

                                       3
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed this First Amendment
to Amended and Restated Securities Purchase Agreement, Standstill Agreement and
Registration Rights Agreement as of the date set forth in the first paragraph
hereof.

The Company:          CABLETRON SYSTEMS, INC.

                      By:  PIYUSH PATEL
                         --------------
                         Name:  Piyush Patel
                         Title: Chief Executive Officer

The Investors:        SILVER LAKE PARTNERS, L.P.

                      By:   Silver Lake Technology Associates, L.L.C.,
                            its general partner

                      By:  JIM DAVIDSON
                         --------------
                         Name:  Jim Davidson
                         Title: Managing Member

                      SILVER LAKE INVESTORS, L.P.

                      By:   Silver Lake Technology Associates, L.L.C.,
                            its general partner

                      By:  JIM DAVIDSON
                         --------------
                         Name:  Jim Davidson
                         Title: Managing Member

                      SILVER LAKE TECHNOLOGY
                      INVESTORS, L.L.C.

                      By:   Silver Lake Technology Associates, L.L.C.,
                            its managing member

                      By:  JIM DAVIDSON
                         --------------
                         Name:  Jim Davidson
                         Title: Managing Member

                                       4
<PAGE>

                      MORGAN STANLEY DEAN WITTER EQUITY FUNDING, INC.

                      By:  JAMES T. KEANE
                         ----------------
                         Name:  James T. Keane
                         Title: Vice President

                      INTEGRAL CAPITAL PARTNERS V, L.P.

                      By:   Integral Capital Management V, LLC,
                            its general partner

                      By:  PAMELA HAGENAH
                         ----------------
                         Name:  Pamela Hagenah
                         Title: Manager

                      INTEGRAL CAPITAL PARTNERS V
                      SIDE FUND, L.P.

                      By:   ICP Management V, LLC,
                            its general partner

                      By:  PAMELA HAGENAH
                         ----------------
                         Name:  Pamela Hagenah
                         Title: Manager

                      ORIGINATORS INVESTMENT PLAN, L.P.

                      By:   MSDW OIP Investors, Inc.,
                            its general partner

                      By:  JAMES T. KEANE
                         ----------------
                         Name:  James T. Keane
                         Title: Vice President

                                       5

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00029-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00029-of-00352.parquet"}]]