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

Document Type Expired Internet-Draft (sip WG)
Expired & archived
Authors Jonathan Rosenberg , Joel Weinberger , Henning Schulzrinne
Last updated 2002-07-05
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state Expired
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


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


Jonathan Rosenberg
Joel Weinberger
Henning Schulzrinne

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)