Connection Reuse in the Session Initiation Protocol (SIP)
RFC 5923

Approval announcement
Draft of message to be sent after approval:

From: The IESG <iesg-secretary@ietf.org>
To: IETF-Announce <ietf-announce@ietf.org>
Cc: Internet Architecture Board <iab@iab.org>,
    RFC Editor <rfc-editor@rfc-editor.org>, 
    sip mailing list <sip@ietf.org>, 
    sip chair <sip-chairs@tools.ietf.org>
Subject: Protocol Action: 'Connection Reuse in the Session Initiation Protocol (SIP)' to Proposed Standard

The IESG has approved the following document:

- 'Connection Reuse in the Session Initiation Protocol (SIP) '
   <draft-ietf-sip-connect-reuse-14.txt> as a Proposed Standard


This document is the product of the Session Initiation Protocol Working Group. 

The IESG contact persons are Cullen Jennings and Robert Sparks.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-sip-connect-reuse-14.txt

Technical summary.

This document enables a pair of communicating proxies to reuse a
congestion-controlled connection between themselves for sending requests
in the forward and backwards direction.  Because the connection is
essentially aliased for requests going in the 
backwards direction, reuse should be predicated upon both the
communicating endpoints authenticating themselves using X.509 certificates
through TLS.  For this reason, we only consider connection reuse for TLS
over TCP and TLS over SCTP.  A single connection 
should not be reused for the TCP or SCTP transport between two peers, and
this document provides insight into why this is the case.  As a remedy, it
suggests using two TCP connections (or two SCTP associations), each opened
pro-actively towards the recipient by the sender.  Finally, this document
also provides guidelines on connection reuse and virtual SIP servers and
the interaction of connection reuse and DNS SRV lookups in SIP.

Working group summary.

There is consensus in the working group to publish this document. 

Document Quality

At SIPiT 18 there were recorded 6 implementations of connect-reuse. 
At SIPiT 19 
there were recorded 27 implementations of connect-reuse (30% of 90 
implementations). This was the last SIPiT apparently polled for
numbers of implementations of this extension.

Personnel

The proto document shepherd for this document was Keith Drage. 
The responsible Area Director was Cullen Jennings.