EXHIBIT 99.1

                           CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350
                             AS ADOPTED PURSUANT TO
                 SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report of Cosine Communications, Inc. (the
"Company") on Form 10-K for the fiscal year ended December 31, 2002 as filed
with the Securities and Exchange Commission on the date hereof (the "Report"),
I, Stephen Goggiano, Director, President and Chief Executive Officer of the
Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:

     (1) The Report fully complies with the requirements of section 13(a) of the
Securities Exchange Act of 1934; and

     (2) The information contained in the Report fairly presents, in all
material respects, the financial condition and results of operations of the
Company.


/s/  Stephen Goggiano
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Stephen Goggiano
Director, President and Chief Executive Officer
March 25, 2003