Subject: [AVT] Agenda for Vienna

From: Colin Perkins <[email-masked]>
Date: Fri, 4 Jul 2003 10:48:00 +0200

Folks,

Enclosed is the agenda for the AVT meeting in Vienna. Please send any
comments or corrections to the chairs. 

Those who have agenda time scheduled are requested to prepare a summary
of the issues they wish to discuss, and to send this to the mailing list
ahead of the meeting. This gives those who won't be attending the
opportunity to post their comments and concerns, and potentially even
reach some consensus, before the meeting time is consumed. It also gives
other participants the opportunity to consider the issue in more depth.
Summary messages SHOULD be sent to the mailing list by Monday 7th July.

We also request that all presenters send us their slides ahead of time,
preferably in PDF format. This has multiple purposes:

  - It streamlines the presentation process by having the presentations 
    on a single laptop.

  - It avoids the delay that sometimes occurs in getting the presentations
    sent to us after the meeting, for inclusion in the minutes.

  - It allows us to preview the presentations to see if they are following
    the guidelines for what should be covered during the meeting.

Presentations SHOULD be submitted to the chairs by Friday 11th July.

Agenda time is conditional on sending both a summary of open issues and
a copy of your slides ahead of the meeting, and 5 minutes ahead doesn't
count!

Those presenting new drafts: briefly describe the basic problem and your
proposed solution, discuss known issues, limitations and problems,
outline where you want input from the working group, and how you wish us
to proceed.  When presenting work which has been previously discussed:
describe only the changes from the previous draft, highlight unresolved
problems, and propose future directions. Presenters are reminded of the
requirements for disclosure of intellectual property relating to
contributions, in section 10 of RFC 2026.

We strongly encourage all participants to read all relevent drafts before
the meeting, and to comment on the open issues raised on the mailing list.

Thanks for your assistance to try to conduct an effective meeting.

Colin, Steve and Magnus

===============================================================================

Audio/Video Transport Working Group

CHAIRS: Steve Casner <[email-masked]>
        Colin Perkins <[email-masked]>
	Magnus Westerlund <[email-masked]>

Monday, 14th July 2003 at 09:00-11:30
=====================================

Introduction, Status and Charter Update			(Chairs)	20
	draft-ietf-avt-rtp-retransmission-08.txt	[Last call]
	draft-ietf-avt-rtcp-feedback-07.txt		[Last call]
	draft-burmeister-avt-rtcp-feedback-sim-02.txt	[Last call]
	draft-ietf-avt-crtp-enhance-07.txt		[RFC Editor]
	draft-ietf-avt-rtp-new-12.txt			[RFC Editor]
	draft-ietf-avt-profile-new-13.txt		[RFC Editor]
	draft-ietf-avt-rtp-mime-06.txt			[RFC Editor]
	draft-ietf-avt-rtcp-bw-05.txt			[RFC Editor]
	draft-ietf-avt-dsr-05.txt			[RFC Editor]
	draft-ietf-avt-evrc-smv-03.txt			[RFC Editor]
	draft-ietf-srtp-08.txt 				[IESG review]
	draft-ietf-avt-mpeg4-simple-07.txt		[IESG review]
	draft-ietf-avt-rtp-clearmode-00.txt
	draft-ietf-avt-mwpp-midi-rtp-07.txt
	draft-lazzaro-avt-mwpp-coding-guidelines-03.txt
	draft-ietf-avt-rtp-jpeg2000-03.txt
	draft-hatanaka-avt-rtp-atracx-02.txt 
	draft-flaks-avt-rtp-ac3-03.txt
	draft-ramalho-rgl-desc-01.txt
	draft-ramalho-rgl-rtpformat-01.txt
	draft-chen-rtp-bv-00.txt
	draft-lazzaro-avt-rtp-framing-contrans-01.txt
	FAX over RTP in ITU-T SG16 Q.14
	New charter

RTCP Extended Reports					(Friedman)	 5
	draft-ietf-avt-rtcp-report-extns-06.txt

RTP Payload Format for DTMF Digits, Tones, etc		(Schulzrinne)	 5
	draft-ietf-avt-rfc2833bis-03.txt

RTP Payload Format for Speex				(Kerr)		15
	draft-herlein-speex-rtp-profile-01.txt

RTP Payload Format for iLBC Speech/iLBC codec		(Duric)		15
	draft-ietf-avt-rtp-ilbc-02.txt
	draft-ietf-avt-ilbc-codec-02.txt

RTP Payload Format for Uncompressed Video		(Gharai)	15
	draft-ietf-avt-uncomp-video-03.txt

RTP Payload Format for H.264 video			(Wenger)	15
	draft-ietf-avt-rtp-h264-02.txt 

RTP Payload Format for 3GPP Timed Text			(Rey)		15
	draft-rey-avt-3gpp-timed-text-00.txt 

RTCP Extensions for SSM with Unicast Feedback		(Ott)		15
	draft-ietf-avt-rtcpssm-04.txt

CRTP over MPLS 						(Ash)		20
	draft-ash-e2e-crtp-hdr-compress-01.txt
	draft-ash-e2e-vompls-hdr-compress-01.txt
	draft-ash-e2e-voip-hdr-comp-rqmts-00.txt

				 - * -

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

---

From: "Ash, Gerald R (Jerry), ALABS" <[email-masked]>
Date: Mon, 7 Jul 2003 12:56:38 -0500

All,

>	draft-ash-e2e-voip-hdr-comp-rqmts-00.txt

Background:

Some service providers (such as AT&T) have plans to migrate large amounts of legacy voice traffic to VoIP, as well as to provide VPN services enabling VoIP.  VoIP over MPLS ('VoMPLS') typically uses the encapsulation voice/RTP/UDP/IP/MPLS.  For an MPLS VPN, the packet header is at least 48 bytes, while the voice payload is typically no more than 30 bytes.  VoIP over MPLS header compression can significantly reduce the VoIP overhead through various compression mechanisms.  This is important on access links where bandwidth is scarce, and can be important on backbone facilities, especially where costs are high (e.g., some global cross-sections).
  
VoIP over MPLS header compression methods have been proposed earlier (March, 2000) in the MPLS working group, however the relevant drafts have expired.  In particular, George Swallow and Lou Berger proposed a 'simple' end-to-end compression scheme in which all first-order differences in the RTP/UDP/IP headers were transmitted, and in which the header compression context was established through RSVP signaling.  The work was accepted into the MPLS WG pending an addition to the MPLS WG charter.

In the I-D's we propose 3 approaches to VoMPLS header compression: a) re-use the methods in cRTP to determine the context and MPLS to route packets, b) re-use the methods in Swallow's and Berger's 'simple' approach to determine the context and MPLS to route packets, and c) re-use the methods in cRTP to determine the context and the SCID (session context ID) to route packets.

The work was presented at the IETF-56 MPLS WG meeting (slides and an excellent set of meetings notes are available at http://ietf.org/proceedings/03mar/index.html.

Issues to discuss:

1. WG charter -- The VoMPLS header compression work is not within the current charter of the AVT WG, so a charter extension is needed.  A discussion among the Transport Area Directors and Sub-IP Area Directors suggested that the work fits most closely within the Transport Area/AVT WG.

2. Protocol extensions -- As detailed in the I-Ds, extensions are proposed to [cRTP] and [cRTP-ENHANCE], which involve a new packet type field to identify FULL_HEADER, CONTEXT_STATE, etc. packets.  New objects are defined for [RSVP-TE].  Extensions are also proposed to RFC2547 VPNs, which create 'SCID routing tables' to allow routing based on the session context ID (SCID).  These extensions need coordination with other WGs (e.g., MPLS).

3. Resynchronization -- E2E VoMPLS using cRTP header compression might not perform well with frequent resynchronizations.  [cRTP-ENHANCE] seems appropriate in this context.  The 'simple' header compression approach would avoid the need for resynchronization, but achieves less efficiency than cRTP.

4. Scalability -- E2E VoMPLS applied between CE-CE would perhaps require a large number of LSPs to be created.  There is concern for CE ability to do the necessary processing and the scalability of the architecture.

4. LDP application -- It would be desirable to signal the VoMPLS tunnels with LDP, since many RFC2547 VPN implementations use LDP as the underlying LSP signaling mechanism.
Please review the documents and raise any issues/comments to the list.

Please review the documents and raise any issues/comments to the list.

Thanks,
Jerry Ash