1
[GRAY CARY WARE & FREIDENRICH LETTERHEAD]
                                                                       EXHIBIT 5


ATTORNEYS AT LAW                                                    OUR FILE NO.
400 HAMILTON AVENUE                                               1020821-907700
PALO ALTO, CA 94301-1825
TEL (415) 328-6561
FAX (415) 327-3699

                                 July 7, 1997

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C.  20549

Ladies and Gentlemen:

      As legal counsel for Bay Networks, Inc., a Delaware corporation (the
"Company"), we are rendering this opinion in connection with the registration
under the Securities Act of 1933, as amended, of up to 137,866 shares of the
Common Stock, $0.01 par value, of the Company which may be issued pursuant to
the exercise of options granted under the Rapid City Communications 1996 Stock
Plan and Rapid City Communications 1997 Stock Plan assumed by the Company (the
"Options"). We have examined all instruments, documents and records which we
deemed relevant and necessary for the basis of our opinion hereinafter
expressed. In such examination, we have assumed the genuineness of all
signatures and the authenticity of all documents submitted to us as originals
and the conformity to the originals of all documents submitted to us as copies.

      We are admitted to practice only in the State of California and we express
no opinion concerning any law other than the law of the State of California, the
corporation laws of the State of Delaware and the federal law of the United
States. As to matters of Delaware corporation law, we have based our opinion
solely upon our examination of such laws and the rules and regulations of the
authorities administering such laws, all as reported in standard, unofficial
compilations. We have not obtained opinions of counsel licensed to practice in
jurisdictions other than the State of California. Based on such examination, we
are of the opinion that the 137,866 shares of Common Stock which may be issued
upon exercise of the Options are duly authorized shares of the Company's Common
Stock, and, when issued against receipt of the consideration therefor in
accordance with the provisions of the Options, will be validly issued, fully
paid and nonassessable.

      We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement referred to above and the use of our name wherever it
appears therein.

                                               Respectfully submitted,

                                               /s/ Gray Cary Ware & Freidenrich
                                               
                                               GRAY CARY WARE & FREIDENRICH
                                               A Professional Corporation