A Transport Independent Bandwidth Modifier for the Session Description Protocol (SDP)
RFC 3890
Document | Type | RFC - Proposed Standard (September 2004; No errata) | |
---|---|---|---|
Author | Magnus Westerlund | ||
Last updated | 2018-12-20 | ||
Replaces | draft-westerlund-mmusic-sdp-bwparam | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3890 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Jon Peterson | ||
Send notices to | (None) |
Network Working Group M. Westerlund Request for Comments: 3890 Ericsson Category: Standards Track September 2004 A Transport Independent Bandwidth Modifier for 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 (2004). Abstract This document defines a Session Description Protocol (SDP) Transport Independent Application Specific Maximum (TIAS) bandwidth modifier that does not include transport overhead; instead an additional packet rate attribute is defined. The transport independent bit-rate value together with the maximum packet rate can then be used to calculate the real bit-rate over the transport actually used. The existing SDP bandwidth modifiers and their values include the bandwidth needed for the transport and IP layers. When using SDP with protocols like the Session Announcement Protocol (SAP), the Session Initiation Protocol (SIP), and the Real-Time Streaming Protocol (RTSP), and when the involved hosts has different transport overhead, for example due to different IP versions, the interpretation of what lower layer bandwidths are included is not clear. Westerlund Standards Track [Page 1] RFC 3890 Bandwidth Modifier for SDP September 2004 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. The Bandwidth Attribute. . . . . . . . . . . . . . . . . 3 1.1.1. Conference Total . . . . . . . . . . . . . . . . 3 1.1.2. Application Specific Maximum . . . . . . . . . . 3 1.1.3. RTCP Report Bandwidth. . . . . . . . . . . . . . 4 1.2. IPv6 and IPv4. . . . . . . . . . . . . . . . . . . . . . 4 1.3. Further Mechanisms that Change the Bandwidth Utilization. . . . . . . . . . . . . . . . . . . . . . . 5 1.3.1. IPsec. . . . . . . . . . . . . . . . . . . . . . 5 1.3.2. Header Compression . . . . . . . . . . . . . . . 5 2. Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2. Terminology. . . . . . . . . . . . . . . . . . . . . . . 6 3. The Bandwidth Signaling Problems . . . . . . . . . . . . . . . 6 3.1. What IP Version is Used. . . . . . . . . . . . . . . . . 6 3.2. Taking Other Mechanisms into Account . . . . . . . . . . 7 3.3. Converting Bandwidth Values. . . . . . . . . . . . . . . 8 3.4. RTCP Problems. . . . . . . . . . . . . . . . . . . . . . 8 3.5. Future Development . . . . . . . . . . . . . . . . . . . 9 3.6. Problem Conclusion . . . . . . . . . . . . . . . . . . . 9 4. Problem Scope. . . . . . . . . . . . . . . . . . . . . . . . . 10 5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 10 6. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 11 6.2. The TIAS Bandwidth Modifier. . . . . . . . . . . . . . . 11 6.2.1. Usage. . . . . . . . . . . . . . . . . . . . . . 11 6.2.2. Definition . . . . . . . . . . . . . . . . . . . 12 6.2.3. Usage Rules. . . . . . . . . . . . . . . . . . . 13 6.3. Packet Rate Parameter. . . . . . . . . . . . . . . . . . 13 6.4. Converting to Transport-Dependent Values . . . . . . . . 14 6.5. Deriving RTCP bandwidth. . . . . . . . . . . . . . . . . 15 6.5.1. Motivation for this Solution. . . . . . . . . . . 15 6.6. ABNF Definitions . . . . . . . . . . . . . . . . . . . . 16 6.7. Example. . . . . . . . . . . . . . . . . . . . . . . . . 16 7. Protocol Interaction . . . . . . . . . . . . . . . . . . . . . 17 7.1. RTSP . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7.2. SIP. . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7.3. SAP. . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. Security Considerations. . . . . . . . . . . . . . . . . . . . 18 9. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 18 10. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 19 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 11.1. Normative References . . . . . . . . . . . . . . . . . . 19 11.2. Informative References . . . . . . . . . . . . . . . . . 19Show full document text