Document:

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                                                                     EXHIBIT 4.3

                                SECOND AMENDMENT

                                     to the

                       PREFERRED SHARES RIGHTS AGREEMENT

                                    between

                       FUSION MEDICAL TECHNOLOGIES, INC.

                                      and

                         EQUISERVE TRUST COMPANY, N.A.

     This Second Amendment (the "Amendment") to the Preferred Shares Rights
Agreement is made and entered into as of April 11, 2001 between FUSION MEDICAL
TECHNOLOGIES, INC., a Delaware corporation (the "Company"), and EQUISERVE TRUST
COMPANY, N.A., as Rights Agent (the "Rights Agent").

                                R E C I T A L S

     WHEREAS, the Company and BankBoston, N.A., predecessor in interest to the
Rights Agent entered into the Preferred Shares Rights Agreement dated as of
October 10, 1997 (as amended on March 30, 1999, the "Rights Agreement"); and

     WHEREAS, EquiServe Trust Company, N.A. has assumed the duties of Rights
Agent from BankBoston, N.A.; and

     WHEREAS, Section 27 of the Rights Agreement provides that prior to the
Distribution Date (as defined in the Rights Agreement), the Company may
supplement or amend the Rights Agreement in any respect without the approval of
any holders of Rights; and
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     WHEREAS, the Company has determined to modify the terms of the Rights
Agreement in certain respects as set forth herein, and in connection therewith,
is entering into this Amendment and directing the Rights Agent to enter into
this Amendment.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, the parties hereto agree as follows:

     1.  Effect of Amendment. Except as expressly provided herein, the Rights
Agreement shall be and remain in full force and effect.

     2.  Capitalized Terms. All capitalized, undefined terms used in this
Amendment shall have the meanings assigned thereto in the Rights Agreement.

     3.  Supplement to Definitions. The definitions contained in Section 1 of
the Rights Agreement shall be supplemented by adding the following:

     "ALLOY" shall mean Alloy Ventures.

     4.  Amendment to Definitions. The following definitions contained in
Section 1 of the Rights Agreement are hereby deleted in their entirety and
amended to read as follows:

     "ACQUIRING PERSON" shall mean any Person who or which, together with all
Affiliates and Associates of such Person, shall be the Beneficial Owner of 15%
or more of the Common Shares then outstanding, but shall not include the
Company, or any Subsidiary of the Company, or any employee benefit plan of the
Company or of any Subsidiary of the Company, or any entity holding Common Shares
for or pursuant to the terms of any such plan. An Acquiring Person shall also
not include SWIB or Alloy, unless and until SWIB or Alloy shall have become the
Beneficial Owner of a percentage of Common Shares then outstanding of 20% or
more, at which time SWIB or Alloy shall be an Acquiring Person. Notwithstanding
the foregoing, no Person shall be deemed to be an Acquiring Person as the result
of an acquisition of Common Shares by the Company which, by reducing the number
of shares outstanding, increases the proportionate number of shares beneficially
owned by such Person to 15% or more (or, in the case of SWIB or Alloy, of 20% or
more) of the Common Shares of the Company then outstanding; PROVIDED, HOWEVER,
that if a Person shall become the Beneficial Owner of 15% or more (or, in the
case of SWIB or Alloy, of 20% or more)of the Common Shares of the Company then
outstanding by reason of share purchases by the Company and shall, after such
share purchases by the Company, become the Beneficial Owner of any additional
Common Shares of the Company (other than pursuant to a dividend or distribution
paid or made by the Company on the outstanding Common Shares in Common Shares or
pursuant to a split or subdivision of the outstanding Common Shares), then such
Person shall be deemed to be an Acquiring Person unless upon becoming the
Beneficial Owner of such additional Common Shares of the Company such Person
does not beneficially own 15% or more (or, in the case of SWIB or Alloy, of 20%
or more) of the Common Shares of the Company then outstanding. Notwithstanding
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the foregoing, (i) if a majority of the Continuing Directors then in office
determines in good faith that a Person who would otherwise be an Acquiring
Person, has become such inadvertently (including, without limitation, because
(A) such Person was unaware that it beneficially owned a percentage of the
Common Shares that would otherwise cause such Person to be an Acquiring Person,
or (B) such Person was aware of the extent of the Common Shares it beneficially
owned, but had no actual knowledge of the consequences of such beneficial
ownership under this Agreement) and without any intention of changing or
influencing control of the Company, and if such Person divested or divests as
promptly as practicable a sufficient number of Common Shares so that such Person
would no longer be an Acquiring Person, then such Person shall not be deemed to
be or to have become an Acquiring Person for any purposes of this Agreement; and
(ii) if, as of the date hereof, any Person is the Beneficial Owner of 15% or
more (or, in the case of SWIB or Alloy, of 20% or more)of the Common Shares
outstanding, such Person shall not be or become an Acquiring Person, unless and
until such time as such Person shall become the Beneficial Owner of additional
Common Shares (other than pursuant to a dividend or distribution paid or made by
the Company on the outstanding Common Shares in Common Shares or pursuant to a
split or subdivision of the outstanding Common Shares), unless, upon becoming
the Beneficial Owner of such additional Common Shares, such Person is not then
the Beneficial Owner of 15% or more (or, in the case of SWIB or Alloy, of 20% or
more) of the Common Shares then outstanding.

     "DISTRIBUTION DATE" shall mean the earlier of (i) the Close of Business on
the tenth day (or such later date as may be determined by action of a majority
of Continuing Directors then in office) after the Shares Acquisition Date (or,
if the tenth day after the Shares Acquisition Date occurs before the Record
Date, the Close of Business on the Record Date) or (ii) the Close of Business on
the tenth Business Day (or such later date as may be determined by action of a
majority of Continuing Directors then in office) after the date that a tender or
exchange offer by any Person (other than the Company, any Subsidiary of the
Company, any employee benefit plan of the Company or of any Subsidiary of the
Company, any Person or entity organized, appointed or established by the Company
for or pursuant to the terms of any such plan or SWIB or Alloy, unless and until
SWIB or Alloy shall have become the Beneficial Owner of a percentage of Common
shares then outstanding of 20% or more), is first published or sent or given
within the meaning of Rule 14d-2(a) of the General Rules and Regulations under
the Exchange Act, if, assuming the successful consummation thereof, such Person
would be an Acquiring Person.

     "TRIGGERING EVENT" shall be deemed to have occurred upon any Person
becoming an Acquiring Person.

     5.  Effective Date. This Amendment shall become effective as of the date
first above written but such effectiveness is contingent upon (a) the execution
of this Amendment by the Company and authorization by the Board of Directors of
the Company approving the Amendment; (b) delivery of a certificate from an
appropriate officer of the Company stating that this Amendment is in compliance
with Section 27 of the Rights Agreement; and (c) the execution and delivery of
this Amendment by the Rights Agent.
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     6.  Governing Law. This Amendment shall be governed by, construed and
enforced in accordance with the laws of the State of Delaware without reference
to the conflicts or choice of law principles thereof.

     7.  Counterparts. This Amendment may be executed in separate counterparts,
each of which when executed and delivered is an original but all of which taken
together constitute one and the same instrument.

     8.  Fax Transmission. A facsimile, telecopy or other reproduction of this
Amendment may be executed by one or more parties hereto, and an executed copy of
this Amendment may be delivered by one or more parties hereto by facsimile or
similar instantaneous electronic transmission device pursuant to which the
signature of or on behalf of such party can be seen, and such execution and
delivery shall be considered valid, binding and effective for all purposes. At
the request of any party hereto, all parties hereto agree to execute an original
of the Amendment as well as any facsimile, telecopy or other reproduction
thereof.

     IN WITNESS WHEREOF, the Company and the Rights Agent have caused this
Amendment to be duly executed as of the day first above written.

                                 FUSION MEDICAL TECHNOLOGIES, INC.

                                 By: /s/ LARRY J. STRAUSS
                                     -----------------------------------------
                                         Larry J. Strauss

                                 Title:  Vice President, Finance and Chief
                                         Financial Officer

                                 EQUISERVE TRUST COMPANY, N.A., as Rights Agent

                                 By: /s/ CAROL MULVEY-EORI
                                      -----------------------------------------
                                         Carol Mulvey-Eori

                                 Title:  Managing Director Client Administration<PAGE>

                                                                     EXHIBIT 4.1

                         REGISTRATION RIGHTS AGREEMENT

                                                               February 27, 2001

     This Registration Rights Agreement (this "Agreement") is made and entered
                                               ---------
into as of the date set forth above (the "Effective Date") by and between
                                          --------------
Extreme Networks, Inc., a Delaware corporation (the "Extreme") and WebStacks,
                                                     -------
Inc. ("Company").
       -------

                                   RECITALS
                                   --------

     WHEREAS, in order to induce the Company to enter into that certain Merger
Agreement and Plan of Reorganization of even date herewith (the "Merger
                                                                 ------
Agreement") and to induce the Company to enter the Merger Agreement and to
---------
consummate the transactions contemplated thereby (the "Merger"), the parties
                                                       ------
hereto desire to enter into this Agreement and to provide registration and other
rights to the Company Shareholders (as defined in the Merger Agreement).

     WHEREAS, pursuant to the Merger, among other things, and subject to the
terms and conditions of the Merger Agreement, all of the shares of Company
Common Stock which are issued and outstanding immediately prior to the Effective
Time of the Merger shall be converted into the right to receive shares of Common
Stock, par value $0.001 per share, of Extreme ("Extreme Common Stock").
                                                --------------------

     Capitalized terms used are not otherwise defined herein have the meanings
set forth in the Merger Agreement.

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

                                   AGREEMENT
                                   ---------

     1.   REGISTRATION RIGHTS.
          -------------------

          1.1  Certain Definitions.  For purposes of this Section 1:
               -------------------

               (a)  Registration. The terms "register," "registered" and
                    ------------             --------    ----------
"registration" refer to a registration effected by preparing and filing a
 ------------
registration statement in compliance with the Securities Act, and the
declaration or ordering of effectiveness of such registration statement.

               (b)  Registrable Securities. The term "Registrable Securities"
                    ----------------------            ----------------------
means (i) the shares of Extreme Common Stock that are issued to the Company
Shareholders in the Merger pursuant to Sections 1.6(a) of the Merger Agreement,
and (ii) any shares of Extreme Common Stock that may be issued as a dividend or
other distribution (including shares of Extreme Common Stock issued in a
subdivision and split of Extreme's outstanding Common Stock) with respect to, or
in exchange for, or in replacement of, shares of Extreme Common Stock described
in clause (i) of this Section 1.1(b) or in this clause (ii); excluding in all
cases, however, from the definition of "Registrable Securities" any such shares
that are: (w) registered

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under the Securities Act other than pursuant to a registration statement filed
pursuant to this Agreement; (x) sold by a person in a transaction in which
rights under this Agreement with respect to such shares are not assigned in
accordance with the terms of this Agreement; (y) sold pursuant to a registration
statement filed pursuant to this Agreement; or (z) sold pursuant to Rule 144
promulgated under the Securities Act or otherwise sold to the public. Only
shares of Extreme Common Stock shall be Registrable Securities. Except as
provided in clauses (i) and (ii) of the first sentence of this Section 1.1(b),
without limitation, the term "Registrable Securities" does not include any
shares of Extreme Common Stock that were not issued in connection with the
Merger.

          (c)  Holder. The term "Holder" means a Company Shareholder who is the
               ------            ------
original holder of any Registrable Securities or any assignee of record of any
Registrable Securities to whom rights under this Agreement have been duly
assigned in accordance with the provisions of this Agreement.

          (d)  Form S-3. The term "Form S-3" means a registration statement
               --------            --------
filed under Form S-3 under the Securities Act, as such is in effect at the
Effective Time, or any successor form of registration statement under the
Securities Act subsequently adopted by the SEC that permits inclusion or
incorporation of a substantial amount of information by reference to other
documents filed by Extreme with the SEC.

          (e)  Rule 415. The term "Rule 415" means Rule 415 promulgated under
               --------            --------
the Securities Act, as such Rule may be amended from time to time, or any
similar or successor rule or regulation hereafter adopted by the SEC.

     1.2  Form S-3 Shelf Registration.
          ---------------------------

          (a)  Filing and Registration Period. Subject to the terms and
               ------------------------------
conditions of this Agreement, consistent with the requirements of applicable
law, Extreme shall file with the SEC within 60 days of the Effective Time (as
defined in the Merger Agreement) a registration statement on Form S-3 for an
offering to be made on a continuous basis pursuant to Rule 415 covering all of
the then outstanding Registrable Securities (the "Shelf Registration"). Extreme
                                                  ------------------
shall use commercially reasonable efforts to cause such Shelf Registration to be
declared effective as soon as practicable after its filing and to keep the Shelf
Registration continuously effective under the Securities Act for a continuous
period of time (such period of time being hereinafter called the "Registration
                                                                  ------------
Period") commencing on the date the Shelf Registration is declared effective
------
under the Securities Act by the SEC (the "Date of Effectiveness") and ending on
                                          ---------------------
the one year anniversary that the Shelf Registration and any Subsequent
Registration (as defined below) has been effective, provided that in the event
that Extreme exercises its right to prohibit sales due to a cessation or
suspension of effectiveness as described in Section 1.2(b) below, then Extreme
shall extend the Registration Period hereunder by the number of trading days
that such sales were so prohibited. Extreme shall have no duty or obligation to
keep the Shelf Registration (or any Subsequent Registration, as defined below)
effective after the expiration of the Registration Period.

          (b)  Subsequent Registration. If the Shelf Registration is filed with
               -----------------------
the SEC and becomes effective under the Securities Act, and the Shelf
Registration or a Subsequent

                                       2
<PAGE>

Registration (as defined below) thereafter ceases to be effective for any reason
at any time during the Registration Period, then Extreme shall use all
reasonable efforts to obtain the prompt withdrawal of any order suspending the
effectiveness thereof, and in any event shall, within thirty days of such
cessation of effectiveness, file an amendment to the Shelf Registration seeking
to obtain the withdrawal of the order suspending the effectiveness thereof, or
file an additional "shelf" registration statement pursuant to Rule 415 covering
all of the then outstanding Registrable Securities (a "Subsequent
                                                       ----------
Registration"). If a Subsequent Registration is filed, Extreme shall use its
------------
best efforts to cause the Subsequent Registration to be declared effective as
soon as practicable after such filing and to keep such registration statement
continuously effective until the end of the Registration Period.

          (c)  Supplements and Amendments. Subject to the provisions of Section
               --------------------------
1.2(g), during the Registration Period Extreme shall supplement and amend the
Shelf Registration or Subsequent Registration, as applicable, if, as and when
required by the Securities Act, the rules and regulations promulgated thereunder
or the rules, regulations or instructions applicable to the registration form
used by Extreme for such Shelf Registration.

          (d)  Timing and Manner of Sales. Any sale of Registrable Securities
               --------------------------
pursuant to a Shelf Registration or a Subsequent Registration under this Section
1.2 may be made only during the Registration Period. In addition, any sale of
Registrable Securities pursuant to a Shelf Registration or a Subsequent
Registration under this Section 1.2 may only be made in accordance with the
method or methods of distribution of such Registrable Securities that are
described in the registration statement for the Shelf Registration (or
Subsequent Registration, as applicable) and permitted by such form of
registration statement. Subject to any other agreements between the Holder and
Extreme or Surviving Corporation, notwithstanding the terms and conditions of
this Section 1, a Holder may also sell Registrable Securities in a bona fide
private offering if the selling Holder provides Extreme with a written opinion
of counsel, satisfactory to counsel to Extreme acting in a reasonable manner,
that such offer and sale is an exempt transaction under the Securities Act and
applicable state securities laws, complies with all requirements for such
exemptions and is not made with use of the prospectus for the Shelf Registration
(or Subsequent Registration, if applicable), or if such resale is made in
accordance with Rule 144 promulgated under the Securities Act (or successor
provisions).

          (e)  No Underwritings. No sale of Registrable Securities under any
               ----------------
Shelf Registration (or Subsequent Registration) effected pursuant to this
Section 1.2 may be effected pursuant to any underwritten offering without
Extreme's prior written consent, which may be withheld in its sole and absolute
discretion.

          (f)  Material Events. In the event of a material development or
               ---------------
potential material development involving Extreme that requires Extreme under the
Securities Act and the regulations thereunder to amend the registration
statement for the Shelf Registration (or Subsequent Registration, as applicable)
in order to cause the prospectus to be current, then Extreme will give written
notice to all Holders as soon as practicable, but in no event more than three
business days after such event that (i) the Shelf Registration (or Subsequent
Registration, as applicable) must be amended and (ii) no sale of Registrable
Securities may be made under the Shelf Registration (or Subsequent Registration,
as applicable) until such Shelf Registration (or Subsequent Registration, as
applicable) has been amended. In the event that Extreme determines

                                       3
<PAGE>

that an amendment to the registration statement is necessary as provided above,
it will use all commercially reasonable efforts to file and cause such amendment
to become effective as soon as practicable; whereupon it will notify the Holders
that the prospectus is current. In the event that sales under the Shelf
Registration (or Subsequent Registration) are prohibited pursuant to this
Section 1.2(f), then after such Shelf Registration (or Subsequent Registration)
has been amended, Extreme will give written notice to all Holders as soon as
practicable, but in no event more than three business days after such amendment,
that sales under the Shelf Registration (or Subsequent Registration) may resume.

          (g)  Trading Window Compliance. The Holders acknowledge that the
               -------------------------
Extreme Insider Trading Compliance Program and Insider Trading Policy, as such
may be amended from time to time, a current copy of which has been provided to
the Company prior to the Closing (the "Extreme Trading Policy") requires that
                                       ----------------------
those directors, officers and employees of Extreme and its subsidiaries and
those other persons whom Extreme determines to be "Access Personnel" or
otherwise subject to the "trading window" and pre-clearance requirements of the
Extreme Trading Policy (and members of their immediate families and households)
are permitted to effect trades in Extreme securities: (i) only during those
specified time periods ("trading windows") in which such persons are permitted
                         ---------------
to make sales, purchases or other trades in Extreme's securities under the
"trading window" provisions of the Extreme Trading Policy; and (ii) only after
pre-clearance of such sales, purchases or other trades with Extreme's Insider
Trading Compliance Officer. If a Holder is or becomes subject to the "trading
window" and/or "pre-clearance" provisions of the Extreme Trading Policy
described above, then, notwithstanding anything herein to the contrary, such
Holder may sell, transfer and dispose of Registrable Securities only during
those trading windows during which such Extreme Access Personnel are permitted
to effect trades in Extreme stock under the Extreme Trading Policy and only
after pre-clearing such trades with Extreme's Insider Trading Compliance Officer
as provided in the Extreme Trading Policy.

          1.3  Limitations. Notwithstanding the provisions of Section 1.2 above,
               -----------
Extreme shall not be obligated to effect any registration, qualification or
compliance of Registrable Securities pursuant to Section 1.2 of this Agreement,
and the Holders shall not be entitled to sell Registrable Securities pursuant to
any registration statement filed under Section 1.2 of this Agreement, as
applicable:

               (a)  if Form S-3 is not then available for such offering by the
Holders;

               (b)  if Extreme shall furnish to the Holders (and all other
holders of Extreme's registrable securities) a certificate signed by an officer
of Extreme stating that, in the good faith judgment of such officer, it would be
detrimental to Extreme and its stockholders for such Permitted Window to be in
effect at such time, due, for example, to the existence of a material
development or potential material development involving Extreme which Extreme
would be obligated to disclose in the prospectus contained in the Shelf
Registration (or Subsequent Registration, as applicable), which disclosure
would, in the good faith judgment of such officer, be premature or otherwise
inadvisable at such time or would have a material adverse affect upon Extreme
and its stockholders, in which event Extreme will have the right to defer the
filing of any such Shelf Registration (or Subsequent Registration, if
applicable) for a period of not more than forty days after delivery of such
certificate to the Holders;

                                       4
<PAGE>

               (c)  if Extreme is acquired and Extreme Common Stock ceases to be
publicly traded and the consideration received in such acquisition is cash
and/or publicly traded securities registered under the Securities Act;

               (d)  in any particular jurisdiction in which Extreme would be
required to qualify to do business or to execute a general consent to service of
process in effecting such registration, qualification or compliance, unless
Extreme is already subject to service of process in such jurisdiction; or

               (e)  if the SEC refuses to declare such registration effective
due to the participation of any particular Holder in such registration (unless
such Holder withdraws all such Holder's Registrable Securities from such
registration statement); or if the manner in which any Registrable Securities
are disposed of pursuant to the Shelf Registration (or Subsequent Registration,
as applicable) is not included within the plan of distribution set forth in the
prospectus for the Shelf Registration (or Subsequent Registration, as
applicable).

          1.4  Shares Otherwise Eligible for Resale. Notwithstanding anything
               ------------------------------------
herein to the contrary, Extreme shall not be obligated to effect or continue to
keep effective any such registration, registration statement, qualification or
compliance with respect to the Registrable Securities held by any particular
Holder:

               (a)  if Extreme or its legal counsel shall have received a "no-
action" letter or similar written confirmation from the SEC that all the
Registrable Securities then held by such Holder may be resold by such Holder
within a three month period without registration under the Securities Act
pursuant to the provisions of Rule 144 promulgated under the Securities Act (or
successor provisions), or otherwise;

               (b)  if legal counsel to Extreme shall deliver a written opinion
to Extreme, its transfer agent and the Holders, in form and substance reasonably
acceptable to Extreme to the effect that all the Registrable Securities then
held by such Holder may be resold by such Holder within a three month period
without registration under the Securities Act pursuant to the provisions of Rule
144 promulgated under the Securities Act, or otherwise; or

               (c)  after expiration or termination of the Registration Period.

          1.5  Expenses. Extreme shall pay all expenses incurred in connection
               --------
with any registration effected by Extreme pursuant to this Agreement (excluding
brokers' discounts and commissions), including, without limitation, all filing,
registration and qualification, printers', legal (including, the reasonable fees
and expenses of one counsel for the Holders as a group) and accounting fees.

          1.6  Obligations of Extreme. Subject to Sections 1.2, 1.3 and 1.4
               ----------------------
above, when required to effect the registration of any Registrable Securities
under the terms of this Agreement, Extreme will, as expeditiously as reasonably
possible:

               (a)  furnish to the Holders such number of copies of the
prospectus for the Shelf Registration (or Subsequent Registration, as
applicable), including a preliminary prospectus (and amendments or supplements
thereto), in conformity with the requirements of the

                                       5
<PAGE>

Securities Act, and such other documents as they may reasonably request in order
to facilitate the disposition of the Registrable Securities owned by them;

               (b)  notify each Holder of Registrable Securities promptly and,
if requested by such Holder, confirm such notification in writing promptly (i)
when a registration statement has become effective and when any post-effective
amendments and supplements thereto become effective, (ii) of any request by the
SEC or any state securities authority for post-effective amendments and
supplements to a registration statement that has become effective, (iii) of the
issuance by the SEC or any state securities authority of any stop order
suspending the effectiveness of a registration statement or the initiation of
any proceedings for that purpose, (iv) of the receipt by Extreme of any
notification with respect to the suspension of the qualification of the
Registrable Securities for sale in any jurisdiction or the initiation or
threatening of any proceeding for such purpose, and (v) of any determination by
Extreme that a post-effective amendment to a registration statement would be
appropriate;

               (c)  use all reasonable efforts to (i) register and qualify the
securities covered by such registration statement under such other securities or
blue sky laws of such jurisdictions in the United States as will be reasonably
requested by the Holders; provided that Extreme will not be required in
connection therewith or as a condition thereto to qualify to do business or to
file a general consent to service of process in any such state or jurisdiction
unless Extreme is already so qualified or subject to service of process,
respectively, in such jurisdiction; and (ii) cause such Registrable Securities
to be registered with or approved by such other governmental agencies or
authorities, including the National Association of Securities Dealers as may be
necessary by virtue of the business and operations of Extreme; provided that
Extreme will not be required to (A) qualify generally to do business in any
jurisdiction where it would not otherwise be required to qualify but for this
paragraph (c), (B) subject itself to taxation in any jurisdiction, or (C)
consent to general service of process in any such jurisdiction except as may be
required by the Securities Act;

               (d)  promptly notify each Holder of Registrable Securities
covered by such registration statement, when a prospectus relating thereto is
required to be delivered under the Securities Act, of the happening of any event
as a result of which the prospectus included in such registration statement, as
then in effect, includes an untrue statement of a material fact or omits to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading in the light of the circumstances then
existing and, subject to the provisions of this Agreement, at the request of any
Holder, prepare and furnish to each Holder of Registrable Securities then
outstanding a reasonable number of copies of a supplement to or an amendment of
the prospectus as may be necessary to correct the untrue statement or omission;

               (e)  make available for inspection by any Holder of Registrable
Securities and any attorney, accountant or other professional retained by any
such Holder (collectively, the "Inspectors"), all financial and other records,
                                ----------
pertinent corporate documents and properties of Extreme (collectively, the
"Records") as shall be reasonably necessary to enable them to exercise their due
 -------
diligence responsibility, and cause Extreme's officers, directors and employees
to supply all information reasonably requested by any Inspectors in connection
with such registration statement; provided, that prior to any such disclosure,
such Inspector executes a non-disclosure agreement in form and substance
acceptable to Extreme. Records

                                       6
<PAGE>

which Extreme determines, in good faith, to be confidential and which it
notifies the Inspectors in writing are confidential shall not be disclosed to
the Inspectors unless (i) the disclosure of such Records is necessary to avoid
or correct a misstatement or omission in such registration statement or (ii) the
release of such Records is ordered pursuant to a subpoena or other order from a
court of competent jurisdiction. Each Holder of Registrable Securities agrees
that information obtained by it as a result of such inspections shall be deemed
confidential and shall not be used by it as the basis for any market
transactions in the securities of Extreme or its affiliates or otherwise
disclosed by it unless and until such is made generally available to the public.
Each Holder of such Registrable Securities further agrees that it will, upon
leaning that disclosure of such Records is sought in a court of competent
jurisdiction, give written notice to Extreme and allow Extreme, at its expense,
to undertake appropriate action to prevent disclosure of the Records deemed
confidential;

               (f)  use its commercially reasonable efforts to cause all such
Registrable Securities to be listed on the Nasdaq National Market and each
securities exchange on which similar securities issued by Extreme are then
listed; and

               (g)  upon the request of any Holder, promptly provide the name,
address and other contract information regarding Extreme's transfer agent for
the Registrable Securities and the CUSIP number for the Registrable Securities.

          1.7  Furnish Information. It shall be a condition precedent to the
               -------------------
obligations of Extreme to take any action pursuant to this Section 1 that the
selling Holders will furnish to Extreme such information regarding themselves,
the Registrable Securities held by them, and the intended method of disposition
and plan of distribution of such Registrable Securities as shall be required to
timely effect the registration of their Registrable Securities.

          1.8  Delay of Registration. No Holder will have any right to obtain or
               ---------------------
seek an injunction restraining or otherwise delaying any registration that is
the subject of this Agreement as the result of any controversy that might arise
with respect to the interpretation or implementation of this Agreement.

          1.9  Indemnification.
               ---------------

               (a)  By Extreme. To the extent permitted by law, Extreme will
                    ----------
indemnify, defend and hold harmless each Holder against any losses, claims,
damages, or liabilities (joint or several), and will indemnify and reimburse
Holder for any reasonable attorneys' fees and other expenses reasonably incurred
by Holder in connection with investigating or defending any such loss, claim,
damage, liability, or action, as incurred, to which such Holder may become
subject under the Securities Act, the Exchange Act or other U.S. federal or
state law, insofar as such losses, claims, damages, or liabilities (or actions
in respect thereof) arise out of or are based upon any of the following
statements, omissions or violations (collectively, a "Violation"):
                                                      ---------

                    (i)  any untrue statement or alleged untrue statement of a
material fact contained in a registration statement filed by Extreme pursuant to
this Agreement

                                       7
<PAGE>

pursuant to which Registrable Securities are sold, including any preliminary
prospectus or final prospectus contained therein or any amendments or
supplements thereto;

                    (ii)   the omission or alleged omission to state in such
registration statement, preliminary prospectus or final prospectus or any
amendments or supplements thereto, a material fact required to be stated
therein, or necessary to make the statements therein not misleading; or

                    (iii)  any violation or alleged violation by Extreme of the
Securities Act, the Exchange Act, any U.S. federal or state securities law or
any rule or regulation promulgated under the Securities Act, the Exchange Act or
any U.S. federal or state securities law in connection with the offering of
Registrable Securities covered by such registration statement;

provided however, that the indemnity agreement contained in this subsection
1.9(a) shall not apply to amounts paid in settlement of any such loss, claim,
damage, liability or action if such settlement is effected without the written
consent of Extreme (which consent shall not be unreasonably withheld), nor shall
Extreme be liable in any such case for any such loss, claim, damage, liability
or action to the extent that it arises out of or is based upon a Violation which
occurs in reliance upon and in conformity with written information furnished
expressly for use in connection with such registration by such Holder.

               (b)  By Selling Holders. To the extent permitted by law, (i) each
                    ------------------
selling Holder will indemnify and hold harmless Extreme, each of its directors,
each of its officers who have signed the registration statement, each Person, if
any, who controls Extreme within the meaning of the Securities Act, any
underwriter and any other Holder selling securities under such registration
statement, against any losses, claims, damages or liabilities (joint or several)
to which Extreme or any such director, officer, controlling person, underwriter
or other such Holder may become subject under the Securities, the Exchange Act
or other federal or state law, insofar as such losses, claims, damages or
liabilities (or actions in respect thereto) arise out of or are based upon any
Violation, in each case to the extent (and only to the extent) that such
Violation occurs in reliance upon and in conformity with written information
furnished by such Holder expressly for use in connection with such registration;
(ii) and each such Holder will indemnify and reimburse Extreme or any such
director, officer, controlling person, underwriter or other Holder for any
reasonable attorneys' fees and other expenses reasonably incurred by Extreme or
any such director, officer, controlling person, underwriter or other Holder in
connection with investigating or defending any such loss, claim, damage,
liability or action, as incurred. Each selling Holder's liability pursuant to
this Section 1.9(b) shall be limited to an amount equal to the net proceeds
received by such selling Holder pursuant to sales under the registration
statement.

               (c)  Notice. Promptly after receipt by an indemnified party under
                    ------
this Section 1.9 of notice of the commencement of any action (including any
governmental action) against such indemnified party, such indemnified party
will, if a claim for indemnification or contribution in respect thereof is to be
made against any indemnifying party under this Section 1.9, deliver to the
indemnifying party a written notice of the commencement thereof and, if the
indemnifying party is Extreme, Extreme shall have the right and obligation to
control the

                                       8
<PAGE>

defense of such action, and if Extreme fails to defend such action it shall
indemnify and reimburse the selling Holders for any reasonable attorneys' fees
and other expenses reasonably incurred by them in connection with investigating
or defending such action; provided, however, that: (i) Extreme shall also have
the right, at its option, to assume and control the defense of any action with
respect to which Extreme or any person entitled to be indemnified by the selling
Holders under Section 1.9(c) is entitled to indemnification from the selling
Holders; (ii) the indemnified party or parties shall have the right to
participate at its own expense in the defense of such action and (but only to
the extent agreed in writing with Extreme and any other indemnifying party
similarly noticed) to assume the defense thereof with counsel mutually
satisfactory to the parties; and (iii) an indemnified party shall have the right
to retain its own counsel, with the fees and expenses of such counsel to be paid
by the indemnifying party, if representation of such indemnified party by the
counsel retained by the indemnifying party would be inappropriate due to an
actual or potential conflict of interests between such indemnified party and any
other party represented by such counsel in such proceeding. The failure of an
indemnified party to deliver written notice to the indemnifying party within a
reasonable time of the commencement of any such action, if prejudicial to the
ability of the indemnifying party to defend such action, shall relieve such
indemnifying party of any liability to the indemnified party under this Section
1.9, but the omission so to deliver written notice to the indemnifying party
will not relieve the indemnifying party of any liability that it may have to any
indemnified party otherwise than under this Section 1.9.

                (d)  Defect Eliminated in Final Prospectus. The foregoing
                     -------------------------------------
indemnity agreements of Extreme and the Holders are subject to the condition
that, insofar as they relate to any Violation made in a preliminary prospectus
but eliminated or remedied in the amended or supplemented prospectus on file
with the SEC and effective at the time the sale of Registrable Securities under
such registration statement occurs (the "Amended Prospectus"), such indemnity
                                         ------------------
agreement shall not inure to the benefit of any person if a copy of the Amended
Prospectus was furnished to the indemnified party and was not furnished to the
person asserting the loss, liability, claim or damage in the action giving rise
to indemnity claims under this Section 1.9, at or prior to the time such action
is required by the Securities Act.

                (e)  Survival. The obligations of Extreme and Holders under this
                     --------
Section 1.9 shall survive the completion of any offering of Registrable
Securities in a registration statement pursuant to this Agreement, and
otherwise.

          1.10  Duration and Termination of Extreme's Obligations. Extreme will
                -------------------------------------------------
have no obligations pursuant to Section 1.2 of this Agreement with respect to
any request or requests for registration (or inclusion in a registration) made
by any Holder or to maintain or continue to keep effective any registration or
registration statement pursuant hereto: (a) after the expiration or termination
of the Registration Period; (b) with respect to a particular Holder if, in the
opinion of counsel to Extreme, all such Registrable Securities proposed to be
sold by such Holder may be sold in a three (3) month period without registration
under the Securities pursuant to Rule 144 promulgated under the Securities or
otherwise; or (c) if all Registrable Securities have been registered and sold
pursuant to a registration effected pursuant to this Agreement and/or have been
transferred in transactions in which registration rights hereunder have not been
assigned in accordance with this Agreement.

                                       9
<PAGE>

          1.11  Acknowledgment of Other Agreements. The Holders acknowledge that
                ----------------------------------
they have been informed by Extreme that other stockholders of Extreme currently
hold certain Form S-3 and other registration rights that may enable such other
stockholders to sell shares of Extreme during the Registration Period or at
other times (thus potentially adversely affecting the receptivity of the market
to the sale of the Registrable Securities pursuant to a registration effected
pursuant to this Agreement).

          1.12  Assignment. Notwithstanding anything herein to the contrary, the
                ----------
rights of a Holder under Section 1 may be assigned only with Extreme's express
prior written consent, which may be withheld in Extreme's sole discretion;
provided, however, that the rights of a Holder under Section 1 may be assigned
without Extreme's express prior written consent: (a) to a Permitted Assignee (as
defined below); or (b) (if applicable) by will or by the laws of intestacy,
descent or distribution, provided that the assignee first agrees in writing to
be bound by all the obligations of the Holders under this Section 1. Any attempt
to assign any rights of a Holder under Section 1 without Extreme's express prior
written consent in a situation in which such consent is required by this Section
shall be null and void and without effect. Subject to the foregoing
restrictions, all rights, covenants and agreements in Section 1 by or on behalf
of the parties hereto will bind and inure to the benefit of the respective
permitted successors and assigns of the parties hereto. Each of the following
parties are "Permitted Assignees" for purposes of this Section 1.12: (a) a trust
whose beneficiaries consist solely of a Holder and such Holder's spouse, lineal
descendants or antecedents, father, mother, brother, sister, adopted child,
and/or adopted grandchild ("Immediate Family Members") and/or the spouse(s) of
any Immediate Family Members and/or the legal guardian(s) of Immediate Family
Members; (b) the personal representative (such as an executor of a Holder's
will), custodian or conservator of a Holder, in the case of the death,
bankruptcy or adjudication of incompetency of that Holder; (c) Immediate Family
Members of a Holder; (d) partners of a Holder that is a partnership; (e) members
of a Holder that is a limited liability company; or (f) a person or entity that
directly or indirectly controls, is controlled by, or is under common control
with, a Holder.

          1.13  The provisions of this Section 1 shall survive and remain
operative and in full force and effect following the Effective Time.

     2.   GENERAL PROVISIONS.
          ------------------

          2.1   Notices. All notices, requests and other communications
                -------
hereunder must be in writing and will be deemed to have been duly given only if
delivered personally against written receipt or by facsimile transmission
against facsimile confirmation or mailed by internationally recognized overnight
courier prepaid, to the parties at the following addresses or facsimile numbers:

     If to Extreme to:

                                             Extreme Networks, Inc.
                                             3585 Monroe Street
                                             Santa Clara, CA  95051
                                             Facsimile No.: (408) 579-3000

                                       10
<PAGE>

                                             Attn: Vito Palermo

     with a copy (which shall not constitute notice to:

                                             Gray Cary Ware & Freidenrich LLP
                                             139 Townsend Street, Suite 400
                                             San Francisco, CA 94107-1922
                                             Facsimile No.: (415) 836-9220
                                             Attn: J. Howard Clowes

     If to the Company to:

                                             WebStacks, Inc.
                                             444 Oakmead Parkway
                                             Sunnyvale, CA 94085
                                             Facsimile No.: (408) 524-3598
                                             Attn: Ratinder Ahuja and Rick Lowe

     with a copy (which shall not constitute notice) to:

                                             Thoits, Love, Hershberger & McLean
                                             245 Lytton Avenue, Suite 300
                                             Palo Alto, CA  94301
                                             Facsimile No.: (650) 325-5572
                                             Attn: Carolyn M. Bruguera

     All such notices, requests and other communications will (a) if delivered
personally to the address as provided in this Section 2.1, be deemed given upon
delivery, (b) if delivered by facsimile transmission to the facsimile number as
provided for in this Section 2.1, be deemed given upon facsimile confirmation,
and (c) if delivered by overnight courier to the address as provided in this
Section 2.1, be deemed given on the earlier of the first Business Day following
the date sent by such overnight courier or upon receipt (in each case regardless
of whether such notice, request or other communication is received by any other
Person to whom a copy of such notice is to be delivered pursuant to this Section
2.1).  Any party from time to time may change its address, facsimile number or
other information for the purpose of notices to that party by giving notice
specifying such change to the other party hereto.

          2.2  Entire Agreement. This Agreement, together with all the exhibits
               ----------------
hereto, constitutes and contains the entire agreement and understanding of the
parties with respect to the subject matter hereof and supersedes any and all
prior negotiations, correspondence, agreements, understandings, duties or
obligations between the parties respecting the subject matter hereof.

          2.3  Governing Law.  This Agreement shall be governed by and construed
               -------------
exclusively in accordance with the internal laws of the State of Delaware as
applied to agreements among Delaware residents entered into and to be performed
entirely within Delaware, excluding that body of law relating to conflict of
laws and choice of law.

                                       11
<PAGE>

          2.4  Severability. If one or more provisions of this Agreement are
               ------------
held to be unenforceable under applicable law, then such provision(s) shall be
excluded from this Agreement and the balance of this Agreement shall be
interpreted as if such provision(s) were so excluded and shall be enforceable in
accordance with its terms.

          2.5  Third Parties. Nothing in this Agreement, express or implied, is
               -------------
intended to confer upon any person, other than the parties hereto and their
successors and assigns, any rights or remedies under or by reason of this
Agreement.

          2.6  Successors and Assigns. Subject to the provisions of Section
               ----------------------
1.12, the provisions of this Agreement shall inure to the benefit of, and shall
be binding upon, the successors and permitted assigns of the parties hereto.

          2.7  Captions. The captions to sections of this Agreement have been
               --------
inserted for identification and reference purposes only and shall not be used to
construe or interpret this Agreement.

          2.8  Counterparts. This Agreement may be executed in counterparts,
               ------------
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument.

          2.9  Costs and Attorneys' Fees. In the event that any action, suit or
               -------------------------
other proceeding is instituted concerning or arising out of this Agreement or
any transaction contemplated hereunder, the prevailing party shall recover all
of such party's reasonable costs and attorneys' fees incurred in each such
action, suit or other proceeding, including any and all appeals or petitions
therefrom.

                                       12
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed this Registration
Rights Agreement as of February 27, 2001.

WEBSTACKS, INC.                         EXTREME NETWORKS, INC.

By:__________________________________   By:__________________________________
   Name:                                   Name:
   Title:                                  Title:

                                       13

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