Session Initiation Protocol Extension to Assure Congestion Safety

Document Type Expired Internet-Draft (sip WG)
Authors Ben Campbell  , Dean Willis 
Last updated 2015-10-14 (latest revision 2003-10-14)
Stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Expired & archived
plain text pdf htmlized bibtex
Stream WG state WG Document
Document shepherd No shepherd assigned
IESG IESG state Expired (IESG: Dead)
Action Holders
Consensus Boilerplate Unknown
Telechat date
Responsible AD Allison Mankin
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This Internet-Draft is no longer active.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 by which a SIP User Agent may require that its requests are not sent over UDP or other transports having congestion-related characteristics similar to those of UDP.


Ben Campbell (
Dean Willis (

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