RTP Topologies
RFC 5117
Document | Type |
RFC - Informational
(January 2008; Errata)
Obsoleted by RFC 7667
|
|
---|---|---|---|
Authors | Stephan Wenger , Magnus Westerlund | ||
Last updated | 2015-10-14 | ||
Replaces | draft-wenger-avt-topologies | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5117 (Informational) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Cullen Jennings | ||
Send notices to | (None) |
Network Working Group M. Westerlund Request for Comments: 5117 Ericsson Category: Informational S. Wenger Nokia January 2008 RTP Topologies Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Abstract This document discusses multi-endpoint topologies used in Real-time Transport Protocol (RTP)-based environments. In particular, centralized topologies commonly employed in the video conferencing industry are mapped to the RTP terminology. Westerlund & Wenger Informational [Page 1] RFC 5117 RTP Topologies January 2008 Table of Contents 1. Introduction ....................................................2 2. Definitions .....................................................3 2.1. Glossary ...................................................3 2.2. Indicating Requirement Levels ..............................3 3. Topologies ......................................................3 3.1. Point to Point .............................................4 3.2. Point to Multipoint Using Multicast ........................5 3.3. Point to Multipoint Using the RFC 3550 Translator ..........6 3.4. Point to Multipoint Using the RFC 3550 Mixer Model .........9 3.5. Point to Multipoint Using Video Switching MCUs ............11 3.6. Point to Multipoint Using RTCP-Terminating MCU ............12 3.7. Non-Symmetric Mixer/Translators ...........................13 3.8. Combining Topologies ......................................14 4. Comparing Topologies ...........................................15 4.1. Topology Properties .......................................15 4.1.1. All to All Media Transmission ......................15 4.1.2. Transport or Media Interoperability ................16 4.1.3. Per Domain Bit-Rate Adaptation .....................16 4.1.4. Aggregation of Media ...............................16 4.1.5. View of All Session Participants ...................16 4.1.6. Loop Detection .....................................17 4.2. Comparison of Topologies ..................................17 5. Security Considerations ........................................17 6. Acknowledgements ...............................................19 7. References .....................................................19 7.1. Normative References ......................................19 7.2. Informative References ....................................20 1. Introduction When working on the Codec Control Messages [CCM], considerable confusion was noticed in the community with respect to terms such as Multipoint Control Unit (MCU), Mixer, and Translator, and their usage in various topologies. This document tries to address this confusion by providing a common information basis for future discussion and specification work. It attempts to clarify and explain sections of the Real-time Transport Protocol (RTP) spec [RFC3550] in an informal way. It is not intended to update or change what is normatively specified within RFC 3550. When the Audio-Visual Profile with Feedback (AVPF) [RFC4585] was developed the main emphasis lay in the efficient support of point to point and small multipoint scenarios without centralized multipoint control. However, in practice, many small multipoint conferences operate utilizing devices known as Multipoint Control Units (MCUs). MCUs may implement Mixer or Translator (in RTP [RFC3550] terminology) Westerlund & Wenger Informational [Page 2] RFC 5117 RTP Topologies January 2008 functionality and signalling support. They may also contain additional application functionality. This document focuses on the media transport aspects of the MCU that can be realized using RTP, as discussed below. Further considered are the properties of Mixers and Translators, and how some types of deployed MCUs deviate from these properties. 2. Definitions 2.1. Glossary ASM - Any Source Multicast AVPF - The Extended RTP Profile for RTCP-based Feedback CSRC - Contributing Source Link - The data transport to the next IP hop MCU - Multipoint Control Unit Path - The concatenation of multiple links, resulting in an end-to-end data transfer. PtM - Point to Multipoint PtP - Point to PointShow full document text