Subject: RE: [AVT] Moving draft-jones-avt-audio-t38-01.txt forward

From: "Vladimir Ulybin" <[email-masked]>
Date: Mon, 3 Nov 2003 08:23:56 +0200

Hello,

Together with advantages (encryption for security needs, the same
port/address for RTP+audio and RTP+t38) the proposed encapsulation of
T.38 into RTP has some disadvantages.

1. The protection from and recovery of packet lost in T.38 is usually
stronger than that of RTP. So, using the RTP error correction for T.38
seems to be problematic.

2. The bi-directional switching between Voice-Band-Data and T.38 modes
remains problematic as in current implementations because the RTP
payload of VBD has no ID of fax session.

The more attractive approach is given in delayed contribution 303 of
CISCO (May 2003, ITU-T, Study Group 16) to support RTP encapsulated into
T.38. That idea is inversed to the discussed one, and has more
capabilities for implementation of reliable fax transfer.

Regards,
Vladimir Ulybin
AudioCodes, Ltd.

-----Original Message-----
From: Paul E. Jones [mailto:[email-masked]]
Sent: Friday, October 31, 2003 11:01 PM
To: [email-masked]
Subject: [AVT] Moving draft-jones-avt-audio-t38-01.txt forward

Folks,

I would like to seek agreement from the AVT group to move the document
audio/t38 document forward.  As I have mentioned previously, the ITU
would
like to incorporate this in T.38 in an amendment to be approved in
January
2004.

The motivation for transporting T.38 via RTP is probably obvious to
most.
In fact, I recall several saying that that is the way it should have
been
done from the outset.  Most certainly, this will prove to be a good step
in
leveraging SRTP for fax to address security needs.

The document is relatively short, just seeking the MIME registration.
The
technical details will be specified in the ITU-T Recommendation T.38.

Can I get agreement to make this an official working group item?  Can we
try
to get this approved by the January 2004 ITU-T SG16 meeting?

Thanks,
Paul

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

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

---

From: Colin Perkins <[email-masked]>
Date: Tue, 4 Nov 2003 18:20:30 +0000

Vladimir,

> capabilities for implementation of reliable fax transfer.

Since the RTP payload format for T.38 is being developed in ITU-T SG16, 
these comments would be better suited to that forum. The MIME type 
registration we are developing here is dependent on that work, and will 
only be published as an RFC when the ITU completes the revision to T.38 
including the payload format.

-- 
Colin Perkins
http://csperkins.org/