An Extension to the Session Initiation protocol to Assure Congestion Safety

Document Type Expired Internet-Draft (individual)
Last updated 2002-07-24
Stream (None)
Intended RFC status (None)
Expired & archived
plain text pdf html bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The Session Initiation Protocol allows the use of UDP for transport of SIP messages. The use of UDP inherently risks network congestion problems, as UDP itself does not define congestion prevention, avoidance, detection, or correction mechanisms. This problem is aggravated by large SIP messages which fragment at the UDP level. Transport protocols in SIP are also negotiated on a per-hop basis, at the SIP level, so SIP proxies may convert from TCP to UDP and so forth. This document defines what it means for SIP nodes to be congestion safe and specifies an extension by which a SIP User Agent may require that its requests are treated in a congestion safe manner.


Dean Willis (
Ben Campbell (

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