March 10, 2004

Juniper Networks, Inc.
1194 North Mathilda Avenue
Sunnyvale, California 94089

Ladies and Gentlemen:

      We have acted as counsel to Juniper Networks, Inc., a Delaware corporation
("Parent"), in connection with the preparation and execution of the Agreement
and Plan of Reorganization (the "Agreement"), dated as of February 9, 2004, by
and among Parent, NetScreen Technologies, Inc., a Delaware corporation
("Company"), and Nerus Acquisition Corp., a Delaware corporation and a wholly
owned subsidiary of Parent ("Merger Sub"), pursuant to which Merger Sub shall be
merged with and into the Company, the separate corporate existence of Merger Sub
shall cease and the Company shall continue as the surviving corporation (the
"Merger"). The Merger and certain proposed transactions incident thereto are
described in the Registration Statement on Form S-4 (the "Registration
Statement") of Parent, which includes the Prospectus relating to the Merger (the
"Prospectus"). This opinion is being rendered pursuant to the requirements of
Item 21(a) of Form S-4 under the Securities Act of 1933, as amended. Unless
otherwise indicated, any capitalized terms used herein and not otherwise defined
have the meaning ascribed to them in the Agreement or the Registration
Statement.

      In connection with this opinion, we have examined and are familiar with
the Agreement, the Registration Statement, and such other presently existing
documents, records and matters of law as we have deemed necessary or appropriate
for purposes of our opinion. In addition, we have assumed, without any
independent investigation or examination thereof (i) that the Merger will be
consummated in accordance with the provisions of the Agreement and in the manner
contemplated by the Prospectus and will be effective under applicable state law,
and that the parties have complied with and, if applicable, will continue to
comply with, the covenants, conditions and other provisions contained in the
Agreement without any waiver, breach or amendment thereof, and (ii) the
continuing truth and accuracy at all relevant times of the statements,
representations and warranties made by Parent and Company in the Agreement or
the Prospectus.

      Based upon and subject to the foregoing, the discussion contained in the
Registration Statement under the caption "United States Federal Income Tax
Consequences of the Merger," subject to the limitations and qualifications
described therein, represents our opinion. Because this opinion is being
delivered prior to the consummation of the proposed transactions described in
the Registration Statement, it must be considered prospective and dependent on
future events. There can be no assurance that changes in the law will not take
place that could affect the material United States federal income tax
consequences of the Merger or that contrary positions may not be taken by the
Internal Revenue Service.

      We undertake no responsibility to advise you of any new developments in
the facts or in the application or interpretation of the federal income tax
laws. Furthermore, in the event any one of the statements, representations,
warranties or assumptions upon which we have relied to issue this opinion is
incorrect, our opinion might be adversely affected and may not be relied upon.

      This opinion is furnished to you solely for use in connection with the
Registration Statement. We hereby consent to the filing of this opinion as an
exhibit to the Registration Statement and to the reference to our firm name in
the Registration Statement under the caption "United States Federal Income Tax
Consequences of the Merger." In giving this consent, we do not thereby admit
that we are in the category

Juniper Networks, Inc.
March 10, 2004
Page 2


of persons whose consent is required under Section 7 of the Securities Act of
1933, as amended, or the rules and regulations of the Securities and Exchange
Commission thereunder, nor do we thereby admit that we are experts with respect
to any part of such Registration Statement within the meaning of the term
"experts" as used in the Securities Act of 1933, as amended, or the rules and
regulations of the Securities and Exchange Commission thereunder.

                                 Very truly yours,


                                 /s/ Wilson Sonsini Goodrich & Rosati


                                 WILSON SONSINI GOODRICH & ROSATI
                                 Professional Corporation