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A Solution to the Heterogeneous Error Response Forking Problem (HERFP) in the Session Initiation Protocol (SIP)

Document Type Expired Internet-Draft (individual)
Expired & archived
Author Rohan Mahy
Last updated 2006-03-07 (Latest revision 2005-07-11)
RFC stream (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
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This Internet-Draft is no longer active.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 SIP protocol defines a role for proxy servers which can forward requests to multiple contacts associated with a specific resource or person. While each of these contacts is expected to send a response of some kind, responses for each branch are not necessarily sent back to the original requester. The proxy server forwards only the "best" final response back to the original request. This behavior causes a situation known as the Herterogeneous Error Response Forking Problem (HERFP) in which the original requester has no opportunity to see or fix a variety of potentially repairable errors. This document describes a backwards compatible solution to the HERFP problem for INVITE transactions.


Rohan Mahy

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