EXHIBIT 32.1

   CERTIFICATION OF THE CHIEF EXECUTIVE OFFICER PURSUANT TO SECTION 906 OF THE
                           SARBANES-OXLEY ACT OF 2002

     I, Scott Kriens, certify, pursuant to 18 U.S.C. Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Annual
Report of Juniper Networks, Inc. on Form 10-K for the year ended December 31,
2003 fully complies with the requirements of Section 13(a) or 15(d) of the
Securities Exchange Act of 1934 and that information contained in such Annual
Report on Form 10-K fairly presents in all material respects the financial
condition and results of operations of Juniper Networks, Inc.

By:    /s/ Scott Kriens
      -------------------------------------
Name:  Scott Kriens
Title: Chairman and Chief Executive Officer
Date:  February 20, 2004