TCP-Based Media Transport in the Session Description Protocol (SDP)
RFC 4145
Document | Type |
RFC - Proposed Standard
(September 2005; No errata)
Updated by RFC 4572
|
|
---|---|---|---|
Authors | Gonzalo Camarillo , David Yon | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4145 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Jon Peterson | ||
Send notices to | <jo@acm.org>, <csp@csperkins.org> |
Network Working Group D. Yon Request for Comments: 4145 Tactical Software, LLC Category: Standards Track G. Camarillo Ericsson September 2005 TCP-Based Media Transport in the Session Description Protocol (SDP) Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document describes how to express media transport over TCP using the Session Description Protocol (SDP). It defines the SDP 'TCP' protocol identifier, the SDP 'setup' attribute, which describes the connection setup procedure, and the SDP 'connection' attribute, which handles connection reestablishment. Yon & Camarillo Standards Track [Page 1] RFC 4145 Connection-Oriented Media September 2005 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Protocol Identifier . . . . . . . . . . . . . . . . . . . . . 3 4. Setup Attribute . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. The Setup Attribute in the Offer/Answer Model. . . . . . 4 5. The Connection Attribute . . . . . . . . . . . . . . . . . . . 5 5.1. Offerer Behaviour. . . . . . . . . . . . . . . . . . . . 6 5.2. Answerer Behaviour . . . . . . . . . . . . . . . . . . . 7 6. Connection Management . . . . . . . . . . . . . . . . . . . . 8 6.1. Connection Establishment . . . . . . . . . . . . . . . . 8 6.2. Connection Reestablishment . . . . . . . . . . . . . . . 8 6.3. Connection Termination . . . . . . . . . . . . . . . . . 8 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Passive/Active . . . . . . . . . . . . . . . . . . . . . 9 7.2. Actpass/Passive. . . . . . . . . . . . . . . . . . . . . 9 7.3. Existing Connection Reuse. . . . . . . . . . . . . . . . 10 7.4. Existing Connection Refusal. . . . . . . . . . . . . . . 10 8. Other Connection-Oriented Transport Protocols. . . . . . . . . 11 9. Security Considerations . . . . . . . . . . . . . . . . . . . 12 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 12.1. Normative References . . . . . . . . . . . . . . . . . . 13 12.2. Informative References . . . . . . . . . . . . . . . . . 13 Yon & Camarillo Standards Track [Page 2] RFC 4145 Connection-Oriented Media September 2005 1. Introduction The Session Description Protocol [4] provides a general-purpose format for describing multimedia sessions in announcements or invitations. SDP uses an entirely textual data format (the US-ASCII subset of UTF-8 [11]) to maximize portability among transports. SDP does not define a protocol; it defines the syntax to describe a multimedia session with sufficient information to participate in that session. Session descriptions may be sent using arbitrary existing application protocols for transport (e.g., SAP [9], SIP [10], RTSP [6], email, HTTP [8], etc.). SDP [4] defines two protocol identifiers: RTP/AVP and UDP, both of which represent unreliable, connectionless protocols. While these transports are appropriate choices for multimedia streams, there are applications for which TCP is more appropriate. This document defines a new protocol identifier, 'TCP', to describe TCP connections in SDP. TCP introduces two new factors when describing a session: how and when should endpoints perform the TCP connection setup procedure. This document defines two new attributes to describe TCP connection setups: 'setup' and 'connection'. 2. Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 [3], and they indicate requirement levels for compliant implementations. 3. Protocol Identifier The following is the ABNF for an 'm' line, as specified by RFC 2327 [4]. media-field = "m=" media space port ["/" integer]Show full document text