Subject: [MMUSIC] SDPCapNeg: Should REQ-50 be core or enhancement ?

From: Flemming Andreasen <[email-masked]>
Date: Sun, 17 Dec 2006 17:42:14 -0500

REQ-50 in draft-andreasen-mmusic-sdp-capability-negotiation-reqts-00.txt 
currently reads as follows:

<quote>
        REQ-50: It MUST be possible to indicate and negotiate alternative
        transport protocol and media type combinations on a per media 
stream
        basis.

           For example, an entity may support a fax call using either T.38
           fax relay ("m=image <port> udptl t38") or PCMU ("m=audio <port>
           RTP/AVP 0"). 
</quote>

REQ-310 suggest that this functionality not be included in the core part 
of the SDP Capability Negotation, but rather as an extension that may or 
may not be supported. If you have an opinion on this issue, please let 
us know.

Thanks

-- Flemming

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From: "Dan Wing" <[email-masked]>
Date: Tue, 19 Dec 2006 10:21:51 -0800

Flemming,

I believe ICE is another example for REQ-5.  For example, ICE allows
specifying TCP in an a=candidate line when the m= line indicates UDP.  That
said, perhaps ICE does this all by itself, outside the scope of SDPCapNeg.

You may want to expand your example for REQ-50 to include T.38 over RTP.
T.38 over RTP was added primarily so that if you had esablished an SRTP call
and needed to use T.38 for fax, the fax communications would also be
encrypted and integrity protected by SRTP.

(www.itu.int is currently unavailable to me, so I can't cite the exact
section of T.38 where T.38-over-RTP was added.)

-d

> -----Original Message-----
> From: Flemming Andreasen [mailto:[email-masked]] 
> Sent: Sunday, December 17, 2006 2:42 PM
> To: mmusic
> Subject: [MMUSIC] SDPCapNeg: Should REQ-50 be core or enhancement ? 
> 
> REQ-50 in 
> draft-andreasen-mmusic-sdp-capability-negotiation-reqts-00.txt

---

From: "Robert R. Gilman" <[email-masked]>
Date: Tue, 19 Dec 2006 12:25:11 -0700

RTP transport for FAX is in section 9.2 of T.38, I believe.
----------------------------------------------------
Bob Gilman       [email-masked]      +1 303 538 3868