Extended Secure RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/SAVPF)
RFC 5124
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RFC - Proposed Standard
(February 2008; No errata)
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Last updated |
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2015-10-14
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IETF
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plain text
pdf
html
bibtex
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WG state
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(None)
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Document shepherd |
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No shepherd assigned
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IESG state |
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RFC 5124 (Proposed Standard)
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Consensus Boilerplate |
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Unknown
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Telechat date |
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Responsible AD |
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Cullen Jennings
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Send notices to |
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magnus.westerlund@ericsson.com, jf.mule@cablelabs.com, dwing@cisco.com, taylor@nortel.com, csp@csperkins.org
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Network Working Group J. Ott
Request for Comments: 5124 Helsinki University of Technology
Category: Standards Track E. Carrara
KTH
February 2008
Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/SAVPF)
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.
Abstract
An RTP profile (SAVP) for secure real-time communications and another
profile (AVPF) to provide timely feedback from the receivers to a
sender are defined in RFC 3711 and RFC 4585, respectively. This memo
specifies the combination of both profiles to enable secure RTP
communications with feedback.
Ott & Carrara Standards Track [Page 1]
RFC 5124 February 2008
Table of Contents
1. Introduction ....................................................3
1.1. Definitions ................................................4
1.2. Terminology ................................................4
2. SAVPF Rules .....................................................4
2.1. Packet Formats .............................................5
2.2. Extensions .................................................5
2.3. Implications from Combining AVPF and SAVP ..................6
3. SDP Definitions .................................................6
3.1. Profile Definition .........................................6
3.2. Attribute Definitions ......................................6
3.3. Profile Negotiation ........................................6
3.3.1. Offer/Answer-Based Negotiation of Session
Descriptions ........................................7
3.3.2. RTSP-Based Negotiation of Session Descriptions ......8
3.3.3. Announcing Session Descriptions .....................9
3.3.4. Describing Alternative Session Profiles .............9
3.4. Examples ..................................................10
4. Interworking of AVP, SAVP, AVPF, and SAVPF Entities ............13
5. Security Considerations ........................................14
6. IANA Considerations ............................................15
7. Acknowledgements ...............................................15
8. References .....................................................15
8.1. Normative References ......................................15
8.2. Informative References ....................................16
Ott & Carrara Standards Track [Page 2]
RFC 5124 February 2008
1. Introduction
The Real-time Transport Protocol, the associated RTP Control Protocol
(RTP/RTCP, RFC 3550) [1], and the profile for audiovisual
communications with minimal control (RFC 3551) [2] define mechanisms
for transmitting time-based media across an IP network. RTP provides
means to preserve timing and detect packet losses, among other
things, and RTP payload formats provide for proper framing of
(continuous) media in a packet-based environment. RTCP enables
receivers to provide feedback on reception quality and allows all
members of an RTP session to learn about each other.
The RTP specification provides only rudimentary support for
encrypting RTP and RTCP packets. Secure RTP (RFC 3711) [4] defines
an RTP profile ("SAVP") for secure RTP media sessions, defining
methods for proper RTP and RTCP packet encryption, integrity, and
replay protection. The initial negotiation of SRTP and its security
parameters needs to be done out-of-band, e.g., using the Session
Description Protocol (SDP, RFC 4566) [6] together with extensions for
conveying keying material (RFC 4567 [7], RFC 4568 [8]).
The RTP specification also provides limited support for timely
feedback from receivers to senders, typically by means of reception
statistics reporting in somewhat regular intervals depending on the
group size, the average RTCP packet size, and the available RTCP
bandwidth. The extended RTP profile for RTCP-based feedback ("AVPF")
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