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                                 April 9, 2001


Cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134-1706

        Re:     Cisco Systems, Inc. -- Registration Statement for Offering of
                7,579 Shares of Common Stock

Dear Ladies and Gentlemen:

        We have acted as counsel to Cisco Systems, Inc., a California
corporation (the "Company"), in connection with the registration on Form S-8
(the "Registration Statement") under the Securities Act of 1933, as amended, of
7,579 shares of the Company's common stock under the Exio Communications, Inc.
1999 Stock Option Plan as assumed by the Company (the "Exio Plan").

        This opinion is being furnished in accordance with the requirements of
Item 8 of Form S-8 and Item 601(b)(5)(i) of Regulation S-K.

        We have reviewed the Company's charter documents and the corporate
proceedings taken by the Company with respect to the assumption of the Exio Plan
and the options outstanding thereunder in connection with the Company's
acquisition of Exio Communications, Inc. Based on such review, we are of the
opinion that, if, as and when the shares of the Company's common stock are
issued and sold (and the consideration therefor received) pursuant to the
provisions of option agreements for the outstanding options assumed under the
Exio Plan and in accordance with the Registration Statement, such shares will be
duly authorized, legally issued, fully paid and nonassessable.

        We consent to the filing of this opinion letter as Exhibit 5 to the
Registration Statement.

        This opinion letter is rendered as of the date first written above and
we disclaim any obligation to advise you of facts, circumstances, events or
developments which hereafter may be brought to our attention and which may
alter, affect or modify the opinion expressed herein. Our opinion is expressly
limited to the matters set forth above and we render no opinion, whether by
implication or otherwise, as to any other matters relating to the Company, the
Exio Plan or the shares of the Company's common stock issuable under such plan.


                                      Very truly yours,



                                      /S/ BROBECK, PHLEGER & HARRISON LLP

