1 Exhibit 23.3 INDEPENDENT ACCOUNTANTS' CONSENT The Board of Directors Unisphere Solutions, Inc.: We consent to the inclusion of our reports dated October 15, 1999, with respect to the consolidated balance sheet of Unisphere Solutions, Inc. and Subsidiaries (an indirect wholly-owned subsidiary of Siemens AG) as of September 30, 1999, and the related consolidated statements of operations, stockholders' equity and cash flows for the period from January 12, 1999 (date of inception) to September 30, 1999, and the related schedule, which reports appear in this Registration Statement, and to the reference to our firm under the heading "Experts" in this Registration Statement on Form S-1. /s/ KPMG LLP Boston, Massachusetts August 1, 2000