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                                                                    EXHIBIT 4.5

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD, PLEDGED OR
OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT
OR PURSUANT TO RULE 144 OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE
CORPORATION AND ITS COUNSEL THAT SUCH REGISTRATION IS NOT REQUIRED.

                            WARRANT TO PURCHASE STOCK

Corporation:                 Multipoint Networks Inc., a California corporation
Number of Shares:            2,500,000
Class of Stock:              Common Stock
Initial Exercise Price:      $0.01 per share
Issue Date:                  May 5, 1997
Expiration Date:             May 5, 2002 (subject to Article 4.1)

     THIS WARRANT CERTIFIES THAT, in consideration of the payment of $1.00 and
for other good and valuable consideration, IMPERIAL BANCORP as of parent
IMPERIAL BANK or IMPERIAL BANK at Holder's election, ("Holder") is entitled to
purchase the number of fully paid and nonassessable shares of the class of
securities (the "Shares") of the corporation (the "Company") at the initial
exercise price per Share (the "Warrant Price") all as set forth above and as
adjusted pursuant to Article 2 of this Warrant subject to the provisions and
upon the terms and conditions set forth of this Warrant.

ARTICLE 1. EXERCISE

     1.1 METHOD OF EXERCISE. Holder may exercise this Warrant by delivering this
Warrant and a duly executed Notice of Exercise in substantially the form
attached as Appendix 1 to the principal office of the Company. Unless Holder is
exercising the conversion right set forth in Section 1.2, Holder shall also
deliver to the Company a check for the aggregate Warrant Price for the Shares
being purchased.

     1.2 CONVERSION RIGHT. In lieu of exercising this Warrant as specified in
Section 1.1, Holder may from time to time convert this Warrant, in whole or in
part, into a number of Shares determined by dividing (a) the aggregate fair
market value of the Shares or other securities otherwise issuable upon exercise
of this Warrant minus the aggregate Warrant Price of such Shares by (b) the fair
market value of one Share. The fair market value of the Shares shall be
determined pursuant to Section 1.4.

     1.3 RIGHT TO PUT WARRANT. At Holder's option, in lieu of exercising its
rights as set forth in Sections 1.1, or 1.2, Holder shall have the right to
require the Company to purchase the Warrant under the circumstances set forth on
Exhibit A.



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     1.4 FAIR MARKET VALUE. If the Shares are traded regularly in a public
market, the fair market value of the Shares shall be the closing price of the
Shares (or the closing price of the Company's stock into which the Shares are
convertible) reported for the business day immediately before Holder delivers
its Notice of Exercise to the Company. If the Shares are not regularly traded in
a public market, the Board of Directors of the Company shall determine fair
market value in its reasonable good faith judgment.

     1.5 DELIVERY OF CERTIFICATE AND NEW WARRANT. Promptly after Holder
exercises or converts this Warrant, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the
Shares not so acquired.

     1.6 REPLACEMENT OF WARRANTS. On receipt of evidence reasonably satisfactory
to the Company of the loss, theft, destruction or mutilation of this Warrant
and, in the case of loss, theft or destruction, on delivery of an indemnity
agreement reasonably satisfactory in form and amount to the Company or, in the
case of mutilation, or surrender and cancellation of this Warrant, the Company
at its expense shall execute and deliver, in lieu of this Warrant, a new warrant
of like tenor.

     1.7 REPURCHASE ON SALE, MERGER, OR CONSOLIDATION OF THE COMPANY.

          1.7.1. "ACQUISITION". For the purpose of this Warrant, "Acquisition"
means any sale, license, or other disposition of all or substantially all of the
assets (including intellectual property) of the Company, or any reorganization,
consolidation, or merger of the Company where the holders of the Company's
securities before the transaction beneficially own less than 50% of the
outstanding voting securities of the surviving entity after the transaction.

          1.7.2. ASSUMPTION OF WARRANT. If upon the closing of any Acquisition
the successor entity assumes the obligations of this Warrant, then this Warrant
shall be exercisable for the same securities, cash, and property as would be
payable for the Shares issuable upon exercise of the unexercised portion of this
Warrant as if such Shares were outstanding on the record date for the
Acquisition and subsequent closing. The Warrant Price shall be adjusted
accordingly. The Company shall use reasonable efforts to cause the surviving
corporation to assume the obligations of this Warrant.

         1.7.3. NONASSUMPTION. If upon the closing of any Acquisition the
successor entity does not assume the obligations of his Warrant and Holder has
not otherwise exercised his Warrant in full, then the unexercised portion of
this Warrant shall be deemed to have been automatically converted pursuant to
Section 1.2 and thereafter Holder shall participate in the acquisition on the
same terms as other holders of the same class of securities of the Company.

          1.7.4. PURCHASE RIGHT. Notwithstanding the foregoing, at the election
of Holder, the Company shall purchase the unexercised portion of this Warrant
for cash upon the closing of any Acquisition for an amount equal to (a) the fair
market value of any consideration that would have been received by Holder in
consideration of the Shares had Holder exercised the unexercised portion of this
Warrant immediately before the record date for determining the shareholders
entitled to participate in the

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proceeds of the Acquisition, less (b) the aggregate Warrant Price of the Shares,
but in no event less than zero.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

         2.1 STOCK DIVIDENDS, SPLITS, ETC. If the Company declares or pays a
dividend on its common stock payable in common stock, or other securities,
subdivides the outstanding common stock into a greater amount of common stock,
then upon exercise of this Warrant, for each Share acquired, Holder shall
receive, without cost to Holder, the total number and kind of securities to
which Holder would have been entitled had Holder owned the Shares of record as
of the date the dividend or subdivision occurred.

     2.2 RECLASSIFICATION, EXCHANGE OR SUBSTITUTION. Upon any reclassification,
exchange, substitution, or other event that results in a change of the number
and/or class of the securities issuable upon exercise or conversion of this
Warrant, Holder shall be entitled to receive, upon exercise or conversion of
this Warrant, the number and kind of securities and property that Holder would
have received for the Shares if this Warrant had been exercised immediately
before such reclassification, exchange, substitution, or other event. Such an
event shall include any automatic conversion of the outstanding or issuable
securities of the Company of the same class or series as the Shares to common
stock pursuant to the terms of the Company's Articles of Incorporation upon the
closing of a registered public offering of the Company's common stock. The
Company or its successor shall promptly issue to Holder a new Warrant for such
new securities or other property. The new Warrant shall provide for adjustments
which shall be as nearly equivalent as may be practicable to the adjustments
provided for in this Article 2 including, without limitation, adjustments to the
Warrant Price and to the number of securities or property issuable upon exercise
of the new Warrant. The provisions of this Section 2.2 shall similarly apply to
successive reclassifications, exchanges, substitutions, or other events.

     2.3 ADJUSTMENTS FOR COMBINATIONS, ETC. If the outstanding Shares are
combined or consolidated, by reclassification or otherwise, into a lesser number
of shares, the Warrant Price shall be proportionately increased.

     2.4 NO IMPAIRMENT. The Company shall not, by amendment of its Articles of
Incorporation or through a reorganization, transfer of assets, consolidation,
merger, dissolution, issue, or sale of securities or any other voluntary action,
avoid or seek to avoid the observance or performance of any of the terms to be
observed or performed under this Warrant by the Company, but shall at all times
in good faith assist in carrying out all the provisions of this Article 2 and in
taking all such action as may be necessary or appropriate to protect Holder's
rights under this Article against impairment. If the Company takes any action
affecting the Shares or its common stock other than as described above that
adversely affects Holder's rights under this Warrant, the Warrant Price shall be
adjusted downward and the number of Shares issuable upon exercise of this
Warrant shall be adjusted upward in such a manner that the aggregate Warrant
Price of this Warrant is unchanged.

     2.5 CERTIFICATE AS TO ADJUSTMENTS. Upon each adjustment of the Warrant
Price, the Company at its expense shall promptly compute such adjustment, and
furnish Holder with a certificate of its Chief

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Financial Officer setting forth such adjustment and the facts upon which such
adjustment is based. The Company shall, upon written request, furnish Holder a
certificate setting forth the Warrant Price in effect upon the date thereof and
the series of adjustments leading to such Warrant Price.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

     3.1 REPRESENTATIONS AND WARRANTIES. The Company hereby represents and
warrants to the Holder as follows:

          (a) The initial Warrant Price referenced on the first page of this
Warrant is not greater than the fair market value of the Shares as of the date
of this Warrant.

     (b) All Shares which may be issued upon the exercise of the purchase right
represented by this Warrant, and all securities, if any, issuable upon
conversion of the Shares, shall, upon issuance, be duly authorized, validly
issued, fully paid and nonassessable, and free of any liens and encumbrances
except for restrictions on transfer provided for herein or under applicable
federal and state securities laws.

     3.2 NOTICE OF CERTAIN EVENTS. If the Company proposes at any time (a) to
declare any dividend or distribution upon its common stock, whether in cash,
property, stock, or other securities and whether or not a regular cash dividend;
(b) to offer for subscription pro rata to the holders of any class or series of
its stock any additional shares of stock of any class or series or other rights;
(c) to effect any reclassification or recapitalization of common stock; (d) to
merge or consolidate with or into any other corporation, or sell, lease,
license, or convey all or substantially all of its assets, or to liquidate,
dissolve or wind up; or (e) offer holders of registration rights the opportunity
to participate in an underwritten public offering of the company's securities
for cash, then, in connection with each such event, the Company shall give
Holder (1) at least 10 days prior written notice of the date on which a record
will be taken for such dividend, distribution, or subscription rights (and
specifying the date on which the holders of common stock will be entitled
thereto) or for determining rights to vote, if any, in respect of the
matters referred to in (c) and (d) above; (2) in the case of the matters
referred to in (c) and (d) above at least 10 days prior written notice of the
date when the same will take place (and specifying the date on which the holders
of common stock will be entitled to exchange their common stock for securities
or other property deliverable upon the occurrence of such event); and (3) in the
case of the material referred to in (e) above, the same notice as is given to
the holders of such registration rights.

     3.3 INFORMATION RIGHTS. So long as the Holder holds this Warrant and/or any
of the Shares, the Company shall deliver to the Holder (a) promptly after
mailing, copies of all communiques to the shareholders of the Company, (b)
within one hundred twenty (120) days after the end of each fiscal year of the
Company, the annual audited financial statements of the Company certified by
independent public accountants of recognized standing and (c) within forty-five
(45) days after the end of each of the first three quarters of each fiscal year,
the Company's quarterly, unaudited financial statements.

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     3.4 REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED. The Company
agrees that the Shares shall be subject to the registration rights set forth on
Exhibit B.

ARTICLE 4. MISCELLANEOUS.

     4.1 TERM; NOTICE OF EXPIRATION. This Warrant is exercisable, in whole or in
part, at any time and from time to time on or before the Expiration Date set
forth above. The Company shall give Holder written notice of Holder's right to
exercise this Warrant in the form attached as Appendix 2 not more than 90 days
and not less than 30 days before the Expiration Date. If the notice is not so
given, the Expiration Date shall automatically be extended until 30 days after
the date the Company delivers the notice to Holder.

     4.2 LEGENDS. This Warrant and the Shares (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) shall be
imprinted with a legend in substantially the following form:

THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, AND MAY NOT BE SOLD, PLEDGED OR OTHERWISE TRANSFERRED WITHOUT AN
EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT OR PURSUANT TO RULE 144 OR AN
OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE CORPORATION AND ITS COUNSEL
THAT SUCH REGISTRATION IS NOT REQUIRED.

     4.3 COMPLIANCE WITH SECURITIES LAWS ON TRANSFER. This Warrant and the
Shares issuable upon exercise this Warrant (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) may not be
transferred or assigned in whole or in part without compliance with applicable
federal and state securities laws by the transferor and the transferee
(including, without limitation, the delivery of investment representation
letters and legal opinions reasonably satisfactory to the Company). The Company
shall not require Holder to provide an opinion of counsel if the transfer is to
an affiliate of Holder or if there is no material question as to the
availability of current information as referenced in Rule 144(c), Holder
represents that it has complied with Rule 144(d) and (e) in reasonable detail,
the selling broker represents that it has complied with Rule 144(f), and the
Company is provided with a copy of Holder's notice of proposed sale.

     4.4 TRANSFER PROCEDURE. Subject to the provisions of Section 4.2, Holder
may transfer all or part of this Warrant or the Shares issuable upon exercise of
this Warrant (or the securities issuable, directly or indirectly, upon
conversion of the Shares, if any) by giving the Company notice of the portion of
the Warrant being transferred setting forth the name, address and taxpayer
identification number of the transferee and surrendering this Warrant to the
Company for reissuance to the transferee(s) (and Holder, if applicable). Unless
the Company is filing financial information with the SEC pursuant to the
Securities Exchange Act of 1934, the Company shall have the right to refuse to
transfer any portion of this Warrant to any person who directly competes with
the Company.

     4.5 NOTICES. All notices and other communications from the Company to the
Holder, or vice versa, shall be deemed delivered and effective when given
personally or mailed by first-class registered

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or certified mail, postage prepaid, at such address as may have been furnished
to the Company or the Holder, as the case may be, in writing by the Company or
such Holder from time to time.

     4.6 WAIVER. This Warrant and any term hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of such change, waiver, discharge or termination is
sought.

     4.7 ATTORNEY'S FEES. In the event of any dispute between the parties
concerning the terms and provisions of this Warrant, the party
prevailing in such dispute shall be entitled to collect from the other party
all costs incurred in such dispute, including reasonable attorneys' fees.

     4.8 GOVERNING LAW. This Warrant shall be governed by and construed in
accordance with the laws of the State of California, without giving effect to
its principles regarding conflicts of law.

                                      Multipoint Networks, Inc.


                                      By       /s/ DAVID J. MCCLURE
                                        ----------------------------------------
                                               David J. McClure

                                      Its: President and Chief Executive Officer


                                      By       /s/ ARTHUR WILDER
                                        ----------------------------------------
                                               Arthur Wilder

                                      Its: Acting Chief Financial Officer







                                  Page 6 of 10
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                                   APPENDIX 1

                               NOTICE OF EXERCISE

     1. The undersigned hereby elects to purchase _________ shares of Common
Stock of Multipoint Networks, Inc. pursuant to the terms of the attached
Warrant, and tenders herewith payment of the purchase price of such shares in
full.

     1. The undersigned hereby elects to convert the attached Warrant into
Shares/cash [strike one] in the manner specified in the Warrant. This conversion
is exercised with respect to ___________ of the Shares covered by the Warrant.

     [Strike paragraph that does not apply.]

     2. Please issue a certificate or certificates representing said shares in
the name of the undersigned or in such other name as is specified below:

            Chief Financial Officer
            Controllers Department
            Imperial Bancorp
            P.O. Box 92991
            Los Angeles, CA 90009

     3. The undersigned represents it is acquiring the shares solely for its own
account and not as a nominee for any other party and not with a view toward the
resale or distribution thereof except in compliance with applicable securities
laws.

IMPERIAL BANCORP or IMPERIAL BANK



----------------------------------------
(Signature)

-------------------------
(Date)

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                                   APPENDIX 2

                     NOTICE THAT WARRANT IS ABOUT TO EXPIRE

                           _______________, ____

Chief Financial Officer
Controllers Department
Imperial Bancorp
P.O. Box 92991
Los Angeles, CA 90009

Gentlepersons:

     This is to advise you that the Warrant issued to you described below will
expire on _____________________.

Issuer:

Issue Date:

Class of Security Issuable:

Exercise Price Per Share:

Number of Shares Issuable:

Procedure for Exercise:

     Please contact [name of contact person at (phone number)] with any
questions you may have concerning exercise of the Warrant. This is your only
notice of pending expiration.

Multipoint Networks, Inc.

By:
   ------------------------------------
Its:
    -----------------------------------

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                                    EXHIBIT A

                                    PUT RIGHT

     Subject to the succeeding sentence, upon written notice to the Company,
Holder shall have the right (the "Put Right") to require that the Company
purchase the Warrant from Holder in consideration of the Company's payment to
Holder (due seven days after receipt of Holder's written notice) of $25,000. The
foregoing notwithstanding, Holder may only exercise the Put Right during the
first to occur of the following periods:

     1.   October 31, 1998; or

     2.   The 20 day period ending on the closing of the merger, consolidation
          or sale of assets of the Company; or

     3,   The 20 day period ending on the liquidation, dissolution or winding up
          of the Company.

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                                    EXHIBIT B

                               REGISTRATION RIGHTS

     The Company shall make its best efforts to amend the Investors Rights
Agreement dated _________________________ (the "Agreement") so that the Shares
shall be entitled to "piggy back" registration rights in accordance with the
terms of the Agreement between the Company and its investor(s), if no Agreement
exists then "piggy back" registration rights in accordance with the terms of any
future Agreement.

     The Company agrees that no amendments will be made to the Agreement which
would have an adverse impact on Holder's registration thereunder without the
consent of Holder. By acceptance of the Warrant to which this Exhibit B is
attached, Holder shall not be deemed to be a party to the Agreement, but solely
entitled to the registration rights created thereby.

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