RFC 3581 (rfc3581) - Page 1 of 13

An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing

Alternative Format: Original Text Document
Next >
Network Working Group                                       J. Rosenberg
Request for Comments: 3581                                   dynamicsoft
Category: Standards Track                                 H. Schulzrinne
                                                     Columbia University
                                                             August 2003


       An Extension to the Session Initiation Protocol (SIP) for
                       Symmetric Response Routing

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   The Session Initiation Protocol (SIP) operates over UDP and TCP,
   among others.  When used with UDP, responses to requests are returned
   to the source address the request came from, and to the port written
   into the topmost Via header field value of the request.  This
   behavior is not desirable in many cases, most notably, when the
   client is behind a Network Address Translator (NAT).  This extension
   defines a new parameter for the Via header field, called "rport",
   that allows a client to request that the server send the response
   back to the source IP address and port from which the request
   originated.

















Rosenberg & Schulzrinne     Standards Track
Next >