One document matched: draft-westerlund-avtext-rtcp-sdes-srcname-00.txt
Network Working Group M. Westerlund
Internet-Draft B. Burman
Intended status: Standards Track P. Sandgren
Expires: April 26, 2012 Ericsson
October 24, 2011
RTCP SDES Item SRCNAME to Label Individual Sources
draft-westerlund-avtext-rtcp-sdes-srcname-00
Abstract
This document defines a new SDES item called SRCNAME which uniquely
identifies a single media source, like a camera or a microphone.
That way anyone receiving the SDES information from a set of
interlinked RTP sessions can determine which SSRCs are related to the
same source. It can equally be used to label SSRC multiplexed
related streams, such as FEC or Retransmission streams related to the
original source stream in the same session. In addition the new SDES
item is also defined for usage with the SDP source specific media
attribute ("a=ssrc") enabling an end-point to declare and learn the
source bindings ahead of receiving RTP/RTCP packets through
signalling.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on April 26, 2012.
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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
3. SDES Item SRCNAME . . . . . . . . . . . . . . . . . . . . . . 5
4. SRCNAME in SDP . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Simulcast . . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. SVC with multi-session transmission . . . . . . . . . . . 8
5.3. Retransmission . . . . . . . . . . . . . . . . . . . . . . 9
5.4. Forward Error Correction . . . . . . . . . . . . . . . . . 10
6. Usage with the Offer/Answer Model . . . . . . . . . . . . . . 11
7. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
RTP has always been a protocol that supports multiple participants
each sending their own media streams in RTP sessions. Previously
many implementations have aimed only at point to point voice over IP
with a single source in each end-point. Even client implementations
aimed at video conferences have often been built with the assumption
around central mixers that only deliver a single media stream per
media type. However, more advanced client implementations may
transmit multiple streams in the same RTP session and there may be
tight relations between different streams and their SSRCs. For
example, a client with several cameras that uses simulcast to send
streams with different encodings of the video from each camera have
the need of conveying the relation of the streams to the receiver. A
similar example is a client with several cameras that uses SVC multi-
session transmission [RFC6190] and also here the receiver needs to
know which streams relate to which video source. Other examples of
tight relations are a retransmission stream and its original stream
as well as the case of forward error correction (FEC) where a client
can send source streams and associated repair streams.
CNAME is not sufficient to express this relation although that is
commonly inferred from end-points that have only one media stream per
media type. The primary use of CNAME in multi-source usages is
instead to indicate which end-point and what synchronization context
a particular media stream relates to and that usually means that all
streams sent from a client have the same CNAME. We are neither
relying on using the same SSRC for all streams related to a
particular media source as it is not robust against SSRC collision
and forces potentially cascading SSRC changes between sessions.
Also, using the same SSRC is not possible when SSRC-multiplexing is
used.
A common solution to convey the relation between streams is to use
SDP attributes. Session-multiplexed streams can be associated with
an attribute that groups different RTP sessions and SSRC-multiplexed
streams can be grouped at the media level for each RTP session. For
example, in Forward Error Correction Grouping Semantics in the
Session Description Protocol [RFC5956] an SDP media level attribute
called "ssrc-group:FEC-FR" is used for grouping FEC associations when
the different streams from a source are SSRC-multiplexed in the same
RTP session. Using SDP attributes may work fine in the case when the
receivers of the streams also get an SDP describing the bindings of
all the streams, but that is not always the case. One such example
is a conference session where clients are communicating with each
other via an RTP Translator. The RTP Translator forwards all RTP and
RTCP traffic from a client to all other clients and the clients can
be prepared to receive any number of streams of certain specified
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media. When a new client joins the session the other clients may not
be notified with a SIP Update including a new SDP, instead the
clients will detect the new client's streams via RTP and RTCP. In
this case there is no way for a client to identify if certain streams
are related to each other since that information only was included in
the SDP.
RTP Retransmission Payload Format [RFC4588] describes a solution for
finding the association between original streams and retransmission
streams when SSRC-multiplexing is used. The association can be
resolved when the receiver receives a retransmission packet matching
a retransmission request sent earlier. However, the RFC continues
with describing that this mechanism might fail if there are two
outstanding requests for the same packet sequence number in two
different original streams of a session. Therefore, to avoid
ambiguity in unicast a receiver MUST NOT have two outstanding
requests for the same packet sequence number in two different
original streams before the association is resolved. For multicast,
however, this ambiguity cannot be avoided and SSRC-multiplexing of
original and retransmission streams is therefore prohibited in
multicast. By defining a solution for one to one mapping between an
original stream and any supporting streams this issue can be avoided
in the future. Note: This document does not update RFC 4588 to use
this solution, but it may be done in the future.
To enable an RTP session participant to determine the close relation
of different streams without the above mentioned problems, a new
method for identifying such sources is needed. RTP [RFC3550] defines
the Source Description RTCP Packet (SDES), which contains one or more
chunks, each of which is composed of SDES items describing the SSRC
identified in that chunk. None of the present SDES items is,
however, suitable for uniquely identifying a media source.
Therefore we propose that one defines a new SDES item called the
SRCNAME which with a unique label identifies a single media source,
like a camera or a microphone. The source may also be a particular
media mix or conceptual stream, such as the "most active speaker"
output by a RTP mixer performing stream switching. That way anyone
receiving the SDES information from a set of interlinked RTP sessions
or multiple SSRCs in the same session can determine which SSRCs are
the same source. Connecting streams with SRCNAME can be done
irrespective of which multiplexing type is used and it solves the
problems with the current solutions described above.
It is, however, possible that a receiver will receive the RTP streams
before receiving SDES packets with all SRCNAME items and that would
mean that the receiver cannot make the connections between SSRCs and
SRCNAMEs when starting to receive the media. "Source-Specific Media
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Attributes in the Session Description Protocol (SDP)" [RFC5576]
defines a way of declaring different attributes for SSRCs in each
session in SDP and if a new source attribute is added to this
framework it would be suitable for conveying the connections between
SSRCs and SRCNAMEs before the media communication starts. Thus, in
addition to the new SDES item we also define a new SDP source-
specific media attribute called srcname, which enables an end-point
to declare and learn the source bindings ahead of receiving RTP/RTCP
packets. Of course, this new SDP source attribute will not be useful
for the case described above when clients did not get updates with
new client's stream bindings, but it will be useful in most other
cases.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. SDES Item SRCNAME
Source Descriptions are a method that should work with all RTP
topologies (assuming that any intermediary node is supporting this
item) and existing RTP extensions. Thus we propose that one defines
a new SDES item called the SRCNAME which with a unique identifier
identifies a single media source, like a camera, a microphone, a
particular media mix, or conceptual stream. That way anyone
receiving the SDES information from a set of interlinked RTP sessions
or SSRCs in a single session can determine which SSRCs are related to
the same source.
The SRCNAME is RECOMMENDED to be per communication session unique
random identifiers generated according to "Guidelines for Choosing
RTP Control Protocol (RTCP) Canonical Names (CNAMEs)" [RFC6222] with
the addition that a local counter enumerating the sources on the host
also is concatenated to the key in step 4 prior to calculating the
hash. The SRCNAME included in an RTCP packet MUST fulfill the
requirements Section 6.5 in RTP [RFC3550] puts on SDES item values in
general. These requirements is that it is a UTF-8 [RFC3629] string
that have a maximum length of 255 bytes.
This SRCNAME's relation to CNAME is the following. CNAME represents
an end-point and a synchronization context. If the different sources
identified by SRCNAMEs should be played out synchronized when
receiving them in a multi-stream context, then the sources need to be
in the same synchronization context. Thus in all cases, all SSRCs
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with the same SRCNAME will have the same CNAME. A given CNAME may
contain multiple sets of sources using different SRCNAMEs.
The SDES SRCNAME item follows the same format as the other SDES items
defined in RTP [RFC3550]:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRCNAME=TBA1 | length | source name ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When using the SRCNAME SDES item it is equally important to CNAME,
thus it is RECOMMENDED to be included in all full compound RTCP
packets being sent. It MAY also be included in non-compound packets
in cases where the implementation believes that there might be new
receivers needing the information.
4. SRCNAME in SDP
"Source-Specific Media Attributes in the Session Description Protocol
(SDP)" [RFC5576] defines a way of declaring attributes for SSRC in
each session in SDP. With a new SDES item, one can use this
framework to define how also the SRCNAME can be provided in the SDP
for each SSRC in each RTP session, thus enabling an end-point to
declare and learn the source bindings ahead of receiving RTP/RTCP
packets.
Hence, we propose a new SDP source attribute called srcname with the
following structure:
a=ssrc:<ssrc-id> srcname:<srcname>
The srcname value MUST be identical to the SRCNAME value the media
sender will send in the SDES SRCNAME item in the SDES RTCP packets.
FormalABNF syntax [RFC5234] for the "srcname" attribute:
srcname-attr = "srcname:" srcname
ssrcname = byte-string
; The definition of "byte-string" is in RFC 4566.
attribute =/ srcname-attr
; The definition of "attribute" is in RFC 4566.
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5. Examples
This section shows SDP examples of declaring the SRCNAME in SDP.
Only the relevant parts of the SDP are shown to improve readability.
Please note that the below examples are all hypothetical as no
decision has yet been to use the SRCNAME mechanism with the
respective example.
5.1. Simulcast
In this use case the end-point is a client with a single audio source
and two video sources and it uses simulcast for sending different
encodings of the same video source. This example is based on Using
Simulcast in RTP sessions [I-D.westerlund-avtcore-rtp-simulcast].
The following SDP describes this.
s=Simulcast enabled client
m=audio 49200 RTP/AVP 96
a=rtpmap:96 G719/48000/2
a=ssrc:521923924 cname:alice@foo.example.com
a=ssrc:521923924 srcname:2b:45:c7:12:83:e6
a=mid:1
m=video 49300 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 profile-level-id=42c01e
a=imageattr:* send [x=640,y=360] recv [x=640,y=360] [x=320,y=180]
a=ssrc:192392452 cname:alice@foo.example.com
a=ssrc:192392452 srcname:a3:d3:4b:f1:22:12
a=ssrc:834753488 cname:alice@foo.example.com
a=ssrc:834753488 srcname:7a:39:a9:3e:28:f7
a=mid:2
a=content:main
m=video 49400 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 profile-level-id=42c00d
a=imageattr:96 send [x=320,y=180]
a=ssrc:239245219 cname:alice@foo.example.com
a=ssrc:239245219 srcname:a3:d3:4b:f1:22:12
a=ssrc:734623563 cname:alice@foo.example.com
a=ssrc:734623563 srcname:7a:39:a9:3e:28:f7
a=mid:3
a=sendonly
The audio session is proposing to use one stereo stream of G.719 and
the video sessions are proposing to send two different encodings of
each video source, one with the resolution 640x360 and one with
320x180. The end-point also declares the SSRCs it intends to use
with bindings to CNAME and SRCNAME, enabling the receiver of the SDP
to bind together the video streams that originates from the same
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video camera.
The use of the srcname attribute in the SDP is optional and the
information can be retrieved from RTCP reporting, but it will then
not be possible to correctly relate the video sources until the first
RTCP report is received.
5.2. SVC with multi-session transmission
Here an example is shown of a client that uses SVC with multi-session
transmission as described in RTP Payload Format for Scalable Video
Coding [RFC6190]. RTP Payload Format for Scalable Video Coding
[RFC6190] only describes examples for a client with one video source
and the decoder dependencies of the different sessions are grouped
using the Session grouping DDP attribute as defined in Signaling
Media Decoding Dependency in the Session Description Protocol (SDP)
[RFC5583] and implicitly CNAME.
However, if a client has two video sources and wishes to use multi-
session transmission and send streams from both sources in each
session an additional grouping mechanism is needed to group the
different streams in the different sessions. SRCNAME is suitable for
this and here we show an example where the DDP attribute groups the
different sessions and the SRCNAME is used to relate the different
SSRCs in each RTP session to one of the two video sources.
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s=SVC MST client
a=group:DDP L1 L2 L3
m=video 20000 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 profile-level-id=4de00a; packetization-mode=1;
mst-mode=NI-TC; sprop-parameter-sets={sps0},{pps0};
a=ssrc:743947584 cname:bob@foo.example.com
a=ssrc:743947584 srcname:7e:83:c1:82:e8:a6
a=ssrc:283894947 cname:bob@foo.example.com
a=ssrc:283894947 srcname:b3:8d:f1:18:c5:84
a=mid:L1
m=video 20002 RTP/AVP 97
a=rtpmap:97 H264-SVC/90000
a=fmtp:97 profile-level-id=53000c; packetization-mode=1;
mst-mode=NI-T; sprop-parameter-sets={sps1},{pps1};
a=ssrc:492784823 cname:bob@foo.example.com
a=ssrc:492784823 srcname:7e:83:c1:82:e8:a6
a=ssrc:892362397 cname:bob@foo.example.com
a=ssrc:892362397 srcname:b3:8d:f1:18:c5:84
a=mid:L2
a=depend:97 lay L1:96
m=video 20004 RTP/AVP 98
a=rtpmap:98 H264-SVC/90000
a=fmtp:98 profile-level-id=53001F; packetization-mode=1;
mst-mode=NI-T; sprop-parameter-sets={sps2},{pps2};
a=ssrc:184562894 cname:bob@foo.example.com
a=ssrc:184562894 srcname:7e:83:c1:82:e8:a6
a=ssrc:305605682 cname:bob@foo.example.com
a=ssrc:305605682 srcname:b3:8d:f1:18:c5:84
a=mid:L3
a=depend:98 lay L1:96 L2:97
Thus, the client declares that it will send two video streams in each
RTP session and the receiver is then able to relate the streams in
the different sessions by using the SRCNAME binding. Without the
SRCNAME binding it would not be possible for the receiver to know
which streams belong to the same source.
5.3. Retransmission
This use case shows how SRCNAME can be used to connect retransmission
streams to the original streams in the case of SSRC multiplexed RTP
retransmission [RFC4588]. This is included to exemplify how RTP
retransmission could be updated to provide explicit bindings between
the source and the repair stream, but just an example and not a
specification.
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s=SSRC-multiplexed retransmission client
m=audio 49200 RTP/AVP 96
a=rtpmap:96 G719/48000/2
a=ssrc:521923924 cname:carol@foo.example.com
a=ssrc:521923924 srcname:88:3a:93:c1:3f:71
a=mid:1
m=video 49300 RTP/AVP 96 97
a=rtpmap:96 H264/90000
a=rtcp-fb:96 nack
a=fmtp:96 profile-level-id=42c01e
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96;rtx-time=200
a=ssrc:192392452 cname:carol@foo.example.com
a=ssrc:192392452 srcname:7b:6e:23:8b:31:a8
a=ssrc:834753488 cname:carol@foo.example.com
a=ssrc:834753488 srcname:7b:6e:23:8b:31:a8
a=ssrc:682394013 cname:carol@foo.example.com
a=ssrc:682394013 srcname:c4:98:d9:1a:fc:58
a=ssrc:284576129 cname:carol@foo.example.com
a=ssrc:284576129 srcname:c4:98:d9:1a:fc:58
a=mid:2
The client proposes to send two original video streams in the video
session and a retransmission stream for each one of them. The
retransmission streams are associated with the respective original
stream by using the same SRCNAME and a receiver would then know which
original stream a certain retransmission stream is associated with.
This solves the ambiguity problem when SSRC-multiplexing is used for
retransmission and it enables SSRC-multiplexing of original and
retransmission streams to be used also in multicast sessions.
5.4. Forward Error Correction
Forward Error Correction Grouping Semantics in the Session
Description Protocol [RFC5956] defines two SDP attributes for
grouping the associated source and FEC-based repair streams. One can
be used for grouping different RTP sessions and the other can be used
for grouping SSRCs in the same RTP session, i.e. when session-
respective SSRC-multiplexing is used. However, it may be
advantageous to SSRC-multiplex the source streams in one RTP session
and the repair streams in another since that gives a receiver the
possibility to reject the repair session in case it does not support
the proposed FEC. In this case the above mentioned grouping
attributes cannot be used to associate the repair streams with the
respective source stream since grouping of SSRCs cannot be made
across RTP sessions. The following example shows how SRCNAME can be
used for that.
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s=FEC client
a=group:FEC-FR 1 2
m=video 49200 RTP/AVP 100
a=rtpmap:100 MP2T/90000
a=ssrc:847612849 cname:dave@foo.example.com
a=ssrc:847612849 srcname:45:a8:f4:19:b4:c3
a=ssrc:558237845 cname:dave@foo.example.com
a=ssrc:558237845 srcname:b8:58:29:c7:2f:9e
a=mid:1
m=application 49300 RTP/AVP 101
a=rtpmap:101 1d-interleaved-parityfec/90000
a=fmtp:101 L=5; D=10; repair-window=200000
a=ssrc:389572053 cname:dave@foo.example.com
a=ssrc:389572053 srcname:45:a8:f4:19:b4:c3
a=ssrc:185729479 cname:dave@foo.example.com
a=ssrc:185729479 srcname:b8:58:29:c7:2f:9e
a=mid:2
In this example the client proposes to send two video streams in one
session and two repair streams in the other session. The repair
streams are associated with the respective video stream by using the
same SRCNAME. When receiving either this SDP or the SDES SRCNAME
packets a receiver can make the connection between the source streams
and the repair streams. Even a client not receiving the SDP will be
able to do the association if it has established one RTP session for
receiving source streams and another for receiving repair streams.
6. Usage with the Offer/Answer Model
The SDP offer/answer procedures for the a=ssrc is specified in
Source-Specific Media Attributes in the Session Description Protocol
(SDP) [RFC5576].
7. Backward Compatibility
Clients not supporting SRCNAME will not have the possibility to bind
different streams to a specific media source, since they will not
understand the SRCNAME SDES item. However, sending SRCNAME SDES
items to a client not supporting it should not impose any problems
since all clients should be prepared that new SDES items may be
specified according to RTP [RFC3550].
According to the definition of SDP attributes in SDP: Session
Description Protocol [RFC4566], if an attribute is received that is
not understood, it MUST be ignored by the receiver. So a receiver
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not supporting the ssrc attribute will simply ignore it.
Source-Specific Media Attributes in the Session Description Protocol
(SDP) [RFC5576] defines rules of how new source attributes should be
registered, which means that a receiver supporting RFC5576 should be
prepared that new source attributes may be defined. This means that
a user supporting some of the source attributes should not have any
problems when the user receives an SDP with unknown source
attributes.
8. IANA Considerations
Following the guidelines in SDP [RFC4566], in The Session Description
Protocol (SDP) Grouping Framework [RFC5888], and in RTP [RFC3550],
the IANA is requested to register:
1. A new SDES item named SRCNAME, as defined in Section 3. This
item needs to be assigned an identifier TBA1.
2. A new SDP source attribute named srcname, as defined in
Section 4.
9. Security Considerations
The SDES SRCNAMEs being opaque identifiers could potentially carry
additional meanings or function as overt channel. If the SRCNAME
would be permanent between sessions, they have the potential for
compromising the users' privacy as they can be tracked between
sessions. See Guidelines for Choosing RTP Control Protocol (RTCP)
Canonical Names (CNAMEs) [RFC6222] for more discussion.
A third party modification of the srcname labels either in the RTCP
SDES items or in the SDP a=ssrc attribute can cause service
disruption. By modifying labels the wrong streams could be
associated, with potentially serious effects including media
disruptions. If streams that are to be associated aren't associated,
then another type of failures occur. To prevent modification,
insertion or deletion of the srcname labels the carrying channel
needs to be protected by integrity protection and source
authentication. For RTCP various solutions exist, such as SRTP
[RFC3711], DTLS [RFC4347], IPsec [RFC4301]. For protecting the SDP
the signalling channel needs to provide protection. For SIP S/MIME
[RFC3261] are the ideal, and hop by hopTLS [RFC5246] provides at
least some protection, although not perfect. For SDP's retrieved
using RTSP DESCRIBE [RFC2326] TLS would be the RECOMMENDED solution.
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific
Media Attributes in the Session Description Protocol
(SDP)", RFC 5576, June 2009.
[RFC6222] Begen, A., Perkins, C., and D. Wing, "Guidelines for
Choosing RTP Control Protocol (RTCP) Canonical Names
(CNAMEs)", RFC 6222, April 2011.
10.2. Informative References
[I-D.westerlund-avtcore-rtp-simulcast]
Westerlund, M., Burman, B., Lindqvist, M., and F. Jansson,
"Using Simulcast in RTP sessions",
draft-westerlund-avtcore-rtp-simulcast (work in progress),
October 2011.
[RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
Streaming Protocol (RTSP)", RFC 2326, April 1998.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
Westerlund, et al. Expires April 26, 2012 [Page 13]
Internet-Draft RTCP SDES SRCNAME October 2011
[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security", RFC 4347, April 2006.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
July 2006.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding
Dependency in the Session Description Protocol (SDP)",
RFC 5583, July 2009.
[RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
Protocol (SDP) Grouping Framework", RFC 5888, June 2010.
[RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in
the Session Description Protocol", RFC 5956,
September 2010.
[RFC6190] Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis,
"RTP Payload Format for Scalable Video Coding", RFC 6190,
May 2011.
Authors' Addresses
Magnus Westerlund
Ericsson
Farogatan 6
SE-164 80 Kista
Sweden
Phone: +46 10 714 82 87
Email: magnus.westerlund@ericsson.com
Westerlund, et al. Expires April 26, 2012 [Page 14]
Internet-Draft RTCP SDES SRCNAME October 2011
Bo Burman
Ericsson
Farogatan 6
SE-164 80 Kista
Sweden
Phone: +46 10 714 13 11
Email: bo.burman@ericsson.com
Patrik Sandgren
Ericsson
Farogatan 6
SE-164 80 Kista
Sweden
Phone: +46 10 717 97 41
Email: patrik.sandgren@ericsson.com
Westerlund, et al. Expires April 26, 2012 [Page 15]
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