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An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing (RFC3581)

IP.com Disclosure Number: IPCOM000019005D
Original Publication Date: 2003-Aug-01
Included in the Prior Art Database: 2003-Aug-26
Document File: 14 page(s) / 29K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. Rosenberg: AUTHOR [+2]

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.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 12% of the total text.

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 [Page 1]

RFC 3581 Symmetric Response Routing August 2003

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 3

4. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 4

5. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

7. Security Considerations . . . . . . . . . . . . . . . . . . . 6

8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6

9. IAB Considerations . . . . . . . . . . . . . . . . . . . . . . 6

9.1. Problem Definition . . . . . . . . . . . . . . . . . . . 8

9.2. Exit Strategy . . . . . . . . . . . . . . . . . . . . . 8

9.3. Brittleness Introduced by this Specification . . . . . . 9

9.4. Requirements for a Long Term Solution . . . . . . . . . 10

9.5. Issues with Existing NAPT Boxes . . . . . . . . . . . . 10

10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10

11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11.1. Normative References . . . . . . . . . . . . . . . . . . 11

11.2. Informative References . . . . . . . . . . . . . . . . . 11

12. Intellectual Property and Copyright Statements . . . . . . . . 11

13. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12

14. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 13

1. Introduction

The Session Initiation Protocol (SIP) [1] operates over UDP and TCP.

When used with UDP, responses to requests are returned to the source

address the request came from, and to th...