RFC 3581 (rfc3581) - Page 1 of 13
An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing
Alternative Format: Original Text Document
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