Managing Client-Initiated Connections in the Session Initiation Protocol (SIP)
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From: The IESG <email@example.com> To: IETF-Announce <firstname.lastname@example.org> Cc: Internet Architecture Board <email@example.com>, RFC Editor <firstname.lastname@example.org>, dispatch mailing list <email@example.com>, dispatch chair <firstname.lastname@example.org> Subject: Protocol Action: 'Managing Client Initiated Connections in the Session Initiation Protocol (SIP)' to Proposed Standard The IESG has approved the following document: - 'Managing Client Initiated Connections in the Session Initiation Protocol (SIP) ' <draft-ietf-sip-outbound-20.txt> as a Proposed Standard This document is the product of the Dispatch Working Group. The IESG contact persons are Robert Sparks and Cullen Jennings. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-sip-outbound-20.txt
Technical Summary This document defines an extension to the Session Initiation Protocol (SIP) that provides for persistent and reusable connections between SIP User Agents and SIP Proxy Servers. In particular, this allows proxy servers to initiate TCP connections or to send asynchronous UDP datagrams to User Agents in order to deliver requests. However, in a large number of real deployments, many practical considerations, such as the existence of firewalls and Network Address Translators (NATs) or the use of TLS with server-provided certificates, prevent servers from connecting to User Agents in this way. This specification defines behaviors for User Agents, registrars and proxy servers that allow requests to be delivered on existing connections established by the User Agent. It also defines keep alive behaviors needed to keep NAT bindings open and specifies the usage of multiple connections from the User Agent to its Registrar. Working Group Summary The working group process on this document was exceptionally long. The first WG version of the draft appeared in the summer of 2005. Working group last call initiated in the summer of 2006 and extended until the summer of 2008, requiring several iterations of the draft and the assignment of Francois Audet as a "process champion" for the draft within the working group. Most delays seem to have been related to slow cycle time on the part of the authors, but the process was also delayed by a number of changes occurring during the review cycle. Particular sticking points included the keepalive mechanism and a requirement for binding to multiple outbound proxies if so configured. Both were eventually resolved by a widely-accepted compromises. Additional work is being pursued in SIPCORE to allow the use of the keepalive mechanism independently of the outbound mechanism. Document Quality There have been implementations of previous versions of this draft testing at SIPit events since 2005. Personnel Dean Willis is the document shepherd with significant assistance from Francois Audet. Robert Sparks is the responsible area director.