Subject: RFC 3581 on An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing

From: [email-masked]
Date: Tue, 26 Aug 2003 15:47:11 -0700

A new Request for Comments is now available in online RFC libraries.

        RFC 3581

        Title:      An Extension to the Session Initiation Protocol
                    (SIP) for Symmetric Response Routing
        Author(s):  J. Rosenberg, H. Schulzrinne
        Status:     Standards Track
        Date:       August 2003
        Mailbox:    [email-masked],
                    [email-masked]
        Pages:      13
        Characters: 66133
        Updates/Obsoletes/SeeAlso:    None

        I-D Tag:    draft-ietf-sip-symmetric-response-01.txt

        URL:        ftp://ftp.rfc-editor.org/in-notes/rfc3581.txt

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.

This document is a product of the Session Initiation Protocol Working
Group of the IETF.

This is now a Proposed Standard Protocol.

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
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USC/Information Sciences Institute

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