RTP Control Protocol (RTCP) Port for Source-Specific Multicast (SSM) Sessions
RFC 6128
| Document | Type |
RFC - Proposed Standard
(February 2011; No errata)
Updates RFC 5760
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-begen-avt-rtcp-port-for-ssm | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 6128 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Robert Sparks | ||
| Send notices to | (None) | ||
Internet Engineering Task Force (IETF) A. Begen
Request for Comments: 6128 Cisco
Updates: 5760 February 2011
Category: Standards Track
ISSN: 2070-1721
RTP Control Protocol (RTCP) Port for
Source-Specific Multicast (SSM) Sessions
Abstract
The Session Description Protocol (SDP) has an attribute that allows
RTP applications to specify an address and a port associated with the
RTP Control Protocol (RTCP) traffic. In RTP-based source-specific
multicast (SSM) sessions, the same attribute is used to designate the
address and the RTCP port of the Feedback Target in the SDP
description. However, the RTCP port associated with the SSM session
itself cannot be specified by the same attribute to avoid ambiguity,
and thus, is required to be derived from the "m=" line of the media
description. Deriving the RTCP port from the "m=" line imposes an
unnecessary restriction. This document removes this restriction by
introducing a new SDP attribute.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6128.
Begen Standards Track [Page 1]
RFC 6128 RTCP Port for Multicast Sessions February 2011
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................2
2. The 'multicast-rtcp' Attribute ..................................3
3. SDP Example .....................................................3
4. Security Considerations .........................................4
5. IANA Considerations .............................................4
5.1. Registration of SDP Attributes .............................5
6. Acknowledgments .................................................5
7. References ......................................................5
7.1. Normative References .......................................5
7.2. Informative References .....................................5
1. Introduction
The Session Description Protocol (SDP) [RFC4566] has an attribute
that allows RTP applications [RFC3550] to specify an address and a
port associated with the RTP Control Protocol (RTCP) traffic
[RFC3605]. This attribute is called 'rtcp'.
Now consider a network where one or more media senders send RTP
packets to a distribution source, which then multicasts these RTP
packets to multicast receivers using a source-specific multicast
(SSM) arrangement [RFC5760]. The distribution source also multicasts
the forward RTCP traffic (i.e., RTCP sender reports and receiver
reports or their summaries) to the receivers in the same SSM session.
In RTP-based SSM sessions, the 'rtcp' attribute is used to designate
the address and the RTCP port of the Feedback Target in the SDP
description [RFC5760]. However, the RTCP port associated with the
SSM session itself cannot be specified by the same attribute since it
could potentially cause ambiguity. Thus, the multicast RTCP port is
required to be derived from the "m=" line of the media description
Begen Standards Track [Page 2]
RFC 6128 RTCP Port for Multicast Sessions February 2011
(see Section 10.2 of [RFC5760]) by following the +1 rule (see Section
11 of [RFC3550]). However, [RFC3550] lifted the requirement for the
+1 rule since it imposed an unnecessary restriction on RTCP port
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