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                                                                     EXHIBIT 4.3

THIS WARRANT AND THE SECURITIES SUBJECT TO THIS WARRANT HAVE NOT BEEN REGISTERED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"). THESE SECURITIES HAVE
BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE
DISTRIBUTION THEREOF. THESE SECURITIES MAY NOT BE OFFERED, SOLD, PLEDGED, OR
TRANSFERRED UNLESS (I) A REGISTRATION STATEMENT UNDER THE ACT IS IN EFFECT AS TO
THESE SECURITIES OR (II) THERE IS AN OPINION OF COUNSEL, SATISFACTORY TO THE
COMPANY, THAT AN EXEMPTION THEREFROM IS AVAILABLE. THIS WARRANT MUST BE
SURRENDERED TO THE COMPANY PRIOR TO ANY TRANSFER OF ANY INTEREST IN SUCH
WARRANT.



                 WARRANT TO PURCHASE SERIES B PREFERRED STOCK OF

                             JUNIPER NETWORKS, INC.

                          ISSUANCE DATE: June 23, 1997

                         EXPIRATION DATE: June 23, 2002

        This certifies that @Home Network or its permitted assigns (the
"Warrantholder"), is entitled, subject to the terms set forth below, to purchase
from Juniper Networks, Inc., a California corporation, (the "Company") up to
10,000 shares (which number is subject to adjustment as provided herein) of
fully paid and nonassessable Series B Preferred Stock of the Company at the
purchase price of $2.40 per share, subject to adjustment as provided herein,
(the "Purchase Price") at any time or from time to time through the earlier of
June 23, 2002 or the effective date of the Company's initial underwritten public
offering of the Company's equity securities pursuant to a registration statement
under the Act. Such price and number of shares are subject to adjustment as
provided in Section 2 of this Warrant. This Warrant is issued pursuant to the
Warrantholder's sublease of certain office space to the Company.

        1. Definitions.

               As used in this Warrant, the following terms, unless the context
otherwise requires, have the following meanings:

               a. "Company" includes any entity which shall succeed to or assume
obligations of the Company under this Warrant.

               b. "Stock," when used with reference to shares of stock of the
Company, means shares of Series B Preferred Stock of the Company, as presently
defined in the Company's Amended 

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and Restated Articles of Incorporation, and stock of any other class into which
those shares may hereafter be changed.

               c. "Shares" shall mean the shares of Stock purchasable hereunder
and shall include all shares of securities into which the Shares purchasable
hereunder may be converted or changed.

               d. "Warrantholder," "holder of Warrant," "holder," or similar
terms when the context refers to a holder of this Warrant, mean any person who
shall at the time be the registered holder of this Warrant.

        2. Adjustment of Purchase Price and Number of Shares.

               The number and kind of securities purchasable upon the exercise
of this Warrant and the Purchase Price shall be subject to adjustment from time
to time upon the occurrence of certain events, as follows:

               a. Reclassification. In case of any reclassification or change of
outstanding securities of the class issuable upon exercise of this Warrant
(other than upon any consolidation or merger of the Company with or into another
corporation unless the Company is the surviving corporation, or upon the sale of
all or substantially all of the assets of the Company) then, and in any such
case, the holder of this Warrant, upon the exercise hereof at any time after the
consummation of such reclassification or change shall be entitled to receive in
lieu of each share of Stock theretofore issuable upon exercise of this Warrant,
the kind and amount of shares of stock, other securities, money and property
received upon such reclassification or change by a holder of one share of Stock.
The provisions of this subsection (a) shall similarly apply to successive
reclassifications or changes.

               b. Subdivision or Combination of Stock. If the Company at any
time while this Warrant remains outstanding and unexpired shall subdivide or
combine its Stock, the Purchase Price shall be proportionately decreased in the
case of a subdivision or increased in the case of a combination or the
conversion ratio adjusted.

               c. Stock Dividends. If the Company at any time while this Warrant
is outstanding shall pay a dividend with respect to Stock payable in Stock, or
make any other distribution of Stock with respect to Stock (except any
distribution specifically provided for in the foregoing subsections (a) or (b)),
then the Purchase Price shall be adjusted, effective from and after the date of
determination of shareholders entitled to receive such dividend or distribution,
to that price determined by multiplying the Purchase Price in effect immediately
prior to such date of determination by a fraction, (a) the numerator of which
shall be the total number of shares of Stock outstanding immediately prior to
such dividend or distribution, and (b) the denominator of which shall be the
total number of shares of Stock outstanding immediately after such dividend or
distribution.

               d. Non-Cash Dividends. If the Company at any time while this
Warrant is outstanding shall pay a dividend with respect to Stock payable in
securities other than Stock or other 

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non-cash property, or make any other distribution of such securities or property
with respect to Stock (except any distribution specifically provided for in the
foregoing subsections (a) or (b)), then this Warrant shall represent the right
to acquire upon exercise of this Warrant such securities or property which a
holder of Stock would have been entitled to receive upon such dividend or
distribution, without the payment by the holder of this Warrant of any
additional consideration for such securities or property.

               e. Adjustment of Number of Shares. Upon each adjustment in the
Purchase Price, the number of Shares shall be adjusted, to the nearest whole
share, to the product obtained by multiplying the number of Shares purchasable
immediately prior to such adjustment in the Purchase Price by a fraction, the
numerator of which shall be the Purchase Price immediately prior to such
adjustment and the denominator of which shall be the Purchase Price immediately
thereafter.

               f. Series B Preferred Stock. In the event shares of Series B
Preferred Stock are no longer outstanding, whether by repurchase of such shares
by the Company, conversion of such shares into the Company's common stock
("Common Stock"), or otherwise (each a "Terminal Event"), this Warrant shall be
exercisable into that number of shares of Common Stock into which the Stock
would have been convertible immediately prior to the Terminal Event.

               (g) Notice of Adjustments. Whenever the Purchase Price shall be
adjusted pursuant to Section 2 hereof, the Company shall issue a certificate
signed by its chief financial officer setting forth, in reasonable detail, the
event requiring the adjustment, the amount of the adjustment, the method by
which such adjustment was calculated and the Purchase Price or Prices after
giving effect to such adjustment, and the securities or other property for which
this Warrant may then be exercised, and shall cause a copy of such certificate
to be mailed (by first class mail, postage prepaid) to the holder of this
Warrant.

        3. Exercise Provisions.

               a. Manner of Exercise. This Warrant may be exercised in part or
in whole only by the holder of this Warrant surrendering to the Company at its
principal office in California, this Warrant, together with the exercise form
attached to this Warrant duly executed by the holder together with payment to
the Company in the amount obtained by multiplying the Purchase Price by the
number of shares of Stock designated in the exercise form. Payment may be in
cash or by cashier's or certified bank check payable to the order of the
Company.

               b. Partial Exercise. On any partial exercise, the Company shall
promptly issue and deliver to the holder of this Warrant a new Warrant or
Warrants of like tenor in the name of that holder providing for the right to
purchase that number of shares of Stock as to which this Warrant has not been
exercised.

               c. Net Exercise Rights. Notwithstanding the payment provisions
set forth in this Section 3, the holder may elect to receive shares of Warrant
Stock equal to the value (as determined below) of this Warrant by surrender of
this Warrant at the principal office of the Company together

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with notice of such election, in which event the Company shall issue to the
holder the number of shares of Series B Preferred Stock determined by use of the
following formula:

        X = Y(A-B)
            ------
               A

Where:  X = the number of shares of Series B Preferred Stock to be issued to the
            holder.

        Y = the number of shares of Series B Preferred Stock subject to this
            Warrant.

        A = the Fair Market Value (as defined below) of one (1) share of Series
            B Preferred Stock.

        B = the per share Purchase Price pursuant to this Warrant.

        For purposes of this Section 3, fair market value of a share as of a
particular date shall mean:

                        1) If the Company's registration statement under the
Act, covering its initial underwritten public offering of stock, has been
declared effective by the Securities and Exchange Commission, then the fair
market value of a share shall be the closing price (the last reported sales
price, if not so reported, the average of the last reported bid and asked
prices) of the Company's stock as of the last business day immediately prior to
the exercise of this Warrant.

                        2) If such a registration statement has not been
declared effective, or if it has been declared effective but the offering is not
consummated in accordance with the terms of the underwriting agreement between
the Company and its underwriters relating to such registration statement, then
as determined in good faith by the Company's Board of Directors upon a review of
relevant factors.

        4. Delivery of Stock Certificates.

               Within a reasonable time after full or partial exercise of this
Warrant, the Company at its expense will cause to be issued in the name of and
delivered to the holder of this Warrant, a certificate or certificates for the
number of fully paid and nonassessable shares of Stock to which that holder
shall be entitled upon such exercise, together with any other securities and
property to which that holder is entitled upon such exercise under the terms of
this Warrant. No fractional shares will be issued upon exercise of rights to
purchase under this Warrant. If upon any exercise of this Warrant a fraction of
a share results, the Company will pay the cash value of that fractional
share, calculated on the basis of the closing market price (last trade regular
way if the Stock is traded on the New York or American Stock Exchange, and if
not so traded, the last sale price or mean of the bid and asked prices as
reported by NASDAQ) as of the date of exercise, or, if the Stock is not publicly
traded, then on the basis of the Company's good faith determination of the fair
market value of the Stock.

        5. Compliance with Securities Act; Disposition of Shares of Common
Stock.

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               a. Compliance with Securities Act. The holder of this Warrant, by
acceptance hereof, agrees that this Warrant and the Shares to be issued upon
exercise hereof are being acquired for investment and that he will not offer,
sell or otherwise dispose of this Warrant or any Shares to be issued upon
exercise hereof except under circumstances which will not result in a violation
of the Act. Upon exercise of this Warrant, the holder hereof shall confirm in
writing, in a form satisfactory to the Company, that the Shares are being
acquired for investment and not with a view toward distribution or resale
(unless sale of the Shares has been registered under the Act). Any proposed
transferee of this Warrant or the Shares (except a transferee of the Shares in a
registered public offering) will be required to agree to the provisions of this
Section 5. Certifi cates representing all Shares (unless registered under the
Act) shall be stamped or imprinted with a legend in substantially the following
form:

        THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
        UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"). THESE
        SECURITIES HAVE BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR
        IN CONNECTION WITH, THE DISTRIBUTION THEREOF. THESE SECURITIES MAY NOT
        BE OFFERED, SOLD, PLEDGED, OR TRANSFERRED UNLESS (I) A REGISTRATION
        STATEMENT UNDER THE ACT IS IN EFFECT AS TO THESE SECURITIES OR (II)
        THERE IS AN OPINION OF COUNSEL, SATISFACTORY TO THE COMPANY, THAT AN
        EXEMPTION THEREFROM IS AVAILABLE. THIS CERTIFICATE MUST BE SURRENDERED
        TO THE COMPANY PRIOR TO ANY TRANSFER OF ANY INTEREST IN THE SECURITIES
        REPRESENTED BY THIS CERTIFICATE.

               b. Notice of Proposed Transfers. Prior to any proposed transfer
of this Warrant or any of the Shares, unless there is in effect a registration
statement under the Act covering the proposed transfer, the holder thereof shall
give written notice (the "Notice") to the Company of such holder's intention to
make such transfer. The Notice shall describe the manner and circumstances of
the proposed transfer in sufficient detail. If requested by the Company prior to
the transfer being effected, the holder shall provide to the Company a written
opinion of legal counsel who shall be reasonably satisfactory to the Company,
addressed to the Company and reasonably satisfactory in form and substance to
the Company's counsel, to the effect that the proposed transfer of the Warrant
or the Shares may be effected without registration under the Act. The holder of
such securities shall be entitled to transfer such securities in accordance with
the terms of the Notice only after the Company has consented in writing to such
transfer. Each warrant or stock certificate evidencing the securities so
transferred shall bear the appropriate restrictive legend set forth above,
except that such certificate shall not bear such restrictive legend if in the
opinion of counsel for the Company such legend is not required in order to
establish compliance with any provisions of the securities laws. Transfer of the
Warrant is further restricted by Section 6(e) hereof.

        6. Miscellaneous Provisions.

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               a. Reservation of Stock. The Company covenants that it will at
all times reserve and keep available, solely for issuance upon exercise of this
Warrant, all shares of Stock or other securities from time to time issuable upon
exercise of this Warrant.

               b. Modification. This Warrant and any of its terms may be
changed, waived, or terminated by a written instrument signed by the Company and
the holders of the Warrants representing the right to acquire a majority of the
shares of Stock then subject to issuance upon the exercise of the Warrants.

               c. Replacement. 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 any indemnity
agreement or bond reasonably satisfactory in form and amount to the Company or,
in the case of mutilation, on surrender and cancellation of this Warrant, the
Company at its expense will execute and deliver, in lieu of this Warrant, a new
Warrant of like tenor.

               d. Warrant Agent. The Company may, on written notice to the
holder of this Warrant, appoint an agent having an office in California for the
purposes of issuing Stock or other securities upon the exercise of this Warrant
and of replacing or exchanging this Warrant, and after that appointment any such
issuance, replacement, or exchange shall be made at that office by that agent.

               e. Nontransferability. This Warrant may not be transferred or
assigned without the prior written consent of the Company except, subject to
Section 5(a) and (b), in its entirety to one or more purchasers who agrees to be
bound by all the terms hereof including this paragraph.

               f. Notices. Notices hereunder to the holder of this Warrant shall
be sent by facsimile, certified or registered mail to the address and facsimile
number given to the Company by such holder and shall be deemed given when so
mailed or so transmitted.

               g. Governing Law. This Warrant shall be governed by the laws of
the State of California as applied to contracts entered into in California
between California residents.

Dated:  June 23, 1997              JUNIPER NETWORKS, INC.



                                    By: /s/ Scott Kriens
                                        ----------------------
                                        Scott Kriens, President and Chief
                                        Executive Officer


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                                FORM OF EXERCISE

                  (To be signed only upon exercise of Warrant)


To:     Juniper Networks, Inc.

        The undersigned Holder of the attached Warrant, hereby irrevocably
elects to exercise the purchase right represented by this Warrant as follows:

[ ]     The undersigned elects to purchase for cash or check _______ full
        shares of Common Stock of SpectraNet International Corporation and
        herewith makes payment of $_____ for those shares;

[ ]     The undersigned elects to effect a net exercise of this Warrant,
        exercising this Warrant [ ] in full or [ ] as to the following gross
        number of shares: _________. The undersigned understands that the actual
        number of shares issuable will be determined in accordance with Sections
        1.1 and 2 of this Warrant.

        The undersigned requests that the certificates for the shares be issued
in the name of, and delivered to,
____________________________________________________*, whose address is
______________________________________________________________________________.

Dated: ___________________
                                    (Signature must conform in all respects to 
                                    name of holder as specified on the face of 
                                    the attached Warrant).


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                                    Signature


                                    ------------------------------------
                                    Address


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        * If the stock is to be issued to anyone other than the registered
Holder of this Warrant, this Notice of Exercise must be accompanied by an
opinion of counsel to the effect that such transfer may be effected without
compliance with the registration and prospectus delivery requirements of the
Securities Act of 1933, as amended.