Session Timers in the Session Initiation Protocol (SIP)
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From: The IESG <firstname.lastname@example.org> To: IETF-Announce <email@example.com> Cc: Internet Architecture Board <firstname.lastname@example.org>, RFC Editor <email@example.com>, sip mailing list <firstname.lastname@example.org>, sip chair <email@example.com> Subject: Protocol Action: 'Session Timers in the Session Initiation Protocol (SIP)' to Proposed Standard The IESG has approved the following document: - 'Session Timers in the Session Initiation Protocol (SIP) ' <draft-ietf-sip-session-timer-16.txt> as a Proposed Standard This document is the product of the Session Initiation Protocol Working Group. The IESG contact persons are Allison Mankin and Jon Peterson. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-sip-session-timer-16.txt
Technical Summary This document defines an extension to the Session Initiation Protocol (SIP). This extension allows for a periodic refresh of SIP sessions through a re-INVITE or UPDATE request. The refresh allows both user agents and proxies to determine if the SIP session is still active (primarily to decide whether to clean up state associated with it). The extension defines two new header fields, Session-Expires, which conveys the lifetime of the session, and Min-SE, which conveys the minimum allowed value for the session timer. It advises for a usage of thirty minutes for the minimum at this time, and it recommends use of the session timer extension the sips URI (TLS is used for each hop) so that a hacker cannot lower the timer and minimum. Working Group Summary There was strong support for this document by the working group. The function is important to SIP because of stateful proxies and forking, it had been handled ad hoc. The draft was one of the earliest ones of the WG. It was delayed waiting for an extensive revision to comply with RFC 3261. Protocol Quality The draft had a thorough review on the working group mailing list. Some implementations are in development. It was reviewed for the IESG by Allison Mankin.