Connection Reuse in the Session Initiation Protocol (SIP)

Document Type Expired Internet-Draft (individual)
Last updated 2003-06-25
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


When SIP entities use a connection oriented protocol to send a request, they typically originate their connections from an ephemeral port. The SIP protocol includes mechanisms which insure that responses to a request, and new requests sent in the original direction reuse an existing connection. However, new requests sent in the opposite direction are unlikely to reuse the existing connection. This frequently causes a pair of SIP entities to use one connection for requests sent in each direction, and can result in potential scaling and performance problems. This document proposes requirements and a mechanism which address this deficiency.


Rohan Mahy (

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