--- 1/draft-ietf-sipping-early-disposition-00.txt 2006-02-05 01:48:39.000000000 +0100 +++ 2/draft-ietf-sipping-early-disposition-01.txt 2006-02-05 01:48:39.000000000 +0100 @@ -1,18 +1,18 @@ SIPPING Working Group G. Camarillo Internet-Draft Ericsson -Expires: May 18, 2004 November 18, 2003 +Expires: July 13, 2004 January 13, 2004 The Early Session Disposition Type for the Session Initiation Protocol (SIP) - draft-ietf-sipping-early-disposition-00.txt + draft-ietf-sipping-early-disposition-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. @@ -20,25 +20,25 @@ and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on May 18, 2004. + This Internet-Draft will expire on July 13, 2004. Copyright Notice - Copyright (C) The Internet Society (2003). All Rights Reserved. + Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document defines a new disposition type (early-session) for the Content-Disposition header field in SIP. The treatment of "early-session" bodies is similar to the treatment of "session" bodies. That is, they follow the offer/answer model. Their only difference is that session descriptions whose disposition type is "early-session" are used to establish early media sessions within early dialogs, as opposed to regular sessions within regular dialogs. @@ -46,21 +46,21 @@ Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Issues Related to Early Media Session Establishment . . . . . . 3 4. The Early Session Disposition Type . . . . . . . . . . . . . . . 4 5. Preconditions . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Option tag . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 - 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7 + 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8 Normative References . . . . . . . . . . . . . . . . . . . . . . 8 Informational References . . . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . 9 1. Introduction A SIP [2] user agent establishing an INVITE dialog may need to exchange media with the destination user agent (or user agents if the INVITE forks) or with application servers in the path before the @@ -134,21 +134,25 @@ We define a new disposition type for the Content-Disposition header field: early-session. User agents MUST use early-session bodies to establish early media sessions in the same way as they use session bodies to establish regular sessions, as described in RFC 3261 [2] and in RFC 3264 [3]. Particularly, early-session bodies MUST follow the offer/answer model and MAY appear in the same messages as session bodies do with the exceptions of 2xx responses for an INVITE and ACKs. Nevertheless, it is NOT RECOMMENDED to include early offers in INVITEs because they can fork, and the UAC could receive multiple early answers establishing early media streams at roughly the same - time. + time. It is also NOT RECOMMENDED to use the same transport address + (IP address plus port) in a session body and in an early-session + body. Using different transport addresses (e.g., different ports) to + receive early and regular media makes it easy to detect the start of + the regular media. If a UA needs to refuse an early-session offer, it MUST to so by refusing all the media streams in it. When SDP [5] is used, this is done by setting the port number of all the media streams to zero. This is the same mechanism that UACs use to refuse regular offers that arrive in a response to an empty INVITE. An early media session established using early-session bodies MUST be terminated when its corresponding early dialog is terminated or it @@ -344,21 +348,21 @@ be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Statement - Copyright (C) The Internet Society (2003). All Rights Reserved. + Copyright (C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of