Quality of Service (QoS) Mechanism Selection in the Session Description Protocol (SDP)
RFC 5432
Network Working Group J. Polk
Request for Comments: 5432 S. Dhesikan
Category: Standards Track Cisco Systems
G. Camarillo
Ericsson
March 2009
Quality of Service (QoS) Mechanism Selection
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.
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Polk, et al. Standards Track [Page 1]
RFC 5432 QoS Mechanism Selection in SDP March 2009
Abstract
The offer/answer model for the Session Description Protocol (SDP)
assumes that endpoints somehow establish the Quality of Service (QoS)
required for the media streams they establish. Endpoints in closed
environments typically agree out-of-band (e.g., using configuration
information) regarding which QoS mechanism to use. However, on the
Internet, there is more than one QoS service available.
Consequently, there is a need for a mechanism to negotiate which QoS
mechanism to use for a particular media stream. This document
defines such a mechanism.
Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................3
3. SDP Attributes Definition .......................................3
4. Offer/Answer Behavior ...........................................4
4.1. Offerer Behavior ...........................................4
4.2. Answerer Behavior ..........................................4
4.3. Resource Reservation .......................................5
4.4. Subsequent Offer/Answer Exchanges ..........................5
5. Example .........................................................5
6. IANA Considerations .............................................6
6.1. Registration of the SDP 'qos-mech-send' Attribute ..........6
6.2. Registration of the SDP 'qos-mech-recv' Attribute ..........6
6.3. Registry for QoS Mechanism Tokens ..........................7
7. Security Considerations .........................................7
8. Acknowledgements ................................................7
9. References ......................................................8
9.1. Normative References .......................................8
9.2. Informative References .....................................8
Polk, et al. Standards Track [Page 2]
RFC 5432 QoS Mechanism Selection in SDP March 2009
1. Introduction
The offer/answer model [RFC3264] for SDP [RFC4566] does not provide
any mechanism for endpoints to negotiate the QoS mechanism to be used
for a particular media stream. Even when QoS preconditions [RFC3312]
are used, the choice of the QoS mechanism is left unspecified and is
up to the endpoints.
Endpoints that support more than one QoS mechanism need a way to
negotiate which one to use for a particular media stream. Examples
of QoS mechanisms are RSVP (Resource Reservation Protocol) [RFC2205]
and NSIS (Next Steps in Signaling) [QoS-NSLP].
This document defines a mechanism that allows endpoints to negotiate
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