To: IETF-Announce: ; Subject: Protocol Action: SIP: Session Initiation Protocol to Proposed Standard From: The IESG Date: Tue, 02 Feb 1999 14:30:17 -0500 Cc: RFC Editor Cc: Internet Architecture Board Cc: confctrl@isi.edu Sender: scoya@ns.cnri.reston.va.us The IESG has approved the Internet-Draft 'SIP: Session Initiation Protocol' as a Proposed Standard. This document is the product of the Multiparty Multimedia Session Control Working Group. The IESG contact persons are Scott Bradner and Vern Paxson. Technical Summary SIP is a control protocol for creating, modifying and terminating sessions with one or more participants. These sessions include Internet multimedia conferences, Internet telephone calls and multimedia distribution. Members in a session can communicate via multicast or via a mesh of unicast relations, or a combination of these. SIP supports session descriptions that allow participants to agree on a set of compatible media types. It also supports user mobility by proxying and redirecting requests to the user's current location. SIP is not tied to any particular conference control protocol. There is widespread interest in the protocol, especially for telephony-related applications. Working Group Summary The current SIP protocol spec was the result of a merger of two alternative proposals presented to the WG in early 1996. Since then, the protocol specification has undergone many refinements, including the addition of comprehensive security considerations. Many small problems were found with the specification during this process and corrected, but nothing major was found. In general working group consensus was good. Feature creep has been a problem during SIP development. To reduce this problem somewhat, SIP call control functionality (which is not a core SIP functionality) was removed from the SIP spec and moved to a separate specification. The relationship between SIP and H.323 was a point of discussion during the development of SIP. There is some overlap, but the two protocols come from different problem domains, and do not attempt to tackle precisely the same set of problems. The final specification is the result of much WG discussion, and represents near-unanimous consensus on the details and rough consensus on the proposal as a whole. All of the issues raised during last call have been addressed in the revised specification. The only significant last call change was making the SIP UDP retransmission timers back off exponentially to address congestion concerns. Protocol Quality Vern Paxson reviewed the spec for the IESG. There are a number of implementations. Note to RFC Editor: The IESG requests the following be added as an IESG Note: The IESG intends to charter, in the near future, one or more working groups to produce standards for "name lookup", where such names would include electronic mail addresses and telephone numbers, and the result of such a lookup would be a list of attributes and characteristics of the user or terminal associated with the name. Groups which are in need of a "name lookup" protocol should follow the development of these new working groups rather than using SIP for this function. In addition it is anticipated that SIP will migrate towards using such protocols, and SIP implementors are advised to monitor these efforts.