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 Quarterly Report of Cosine Communications, Inc.
(the "Company") on Form 10-Q for the quarterly period ended June 30, 2002 as
filed with the Securities and Exchange Commission on the date hereof (the
"Report"), I, Stephen Michael 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 Michael Goggiano
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Stephen Michael Goggiano
Director, President and Chief Executive Officer
August 14, 2002