Subject: Re: [AVT] Comments on draft-ietf-avt-rtp-new-11.txt

From: Stephen Casner <[email-masked]>
Date: Sat, 16 Mar 2002 09:01:53 -0800 (PST)

Paul,

A delayed followup... I'd like to discuss this more at IETF this next
week in the AVT meeting to get wider input.  A comment below.

On Thu, 21 Feb 2002, Paul E. Jones wrote:
...
> What I would prefer to have is something like this:
>
> ---------
> RTP relies on the underlying protocol(s) to provide demultiplexing of RTP
> data and RTCP control streams. For UDP and similar protocols, RTP uses an
> even destination port number and the corresponding RTCP stream uses the next
> higher (odd) destination port number. For applications that take a single
> port number as a parameter and derive the RTP and RTCP port pair from that
> number, if an odd number is supplied then the application MUST replace that
> number with the next lower (even) number to use as the base of the port
> pair. For applications in which the RTP and RTCP destination port numbers
> are specified via explicit, separate parameters (using a signaling protocol
> or other means), the application MAY disregard the restrictions that the
> port numbers be even/odd and consecutive although the use of an even/odd
> port pair is still encouraged. The RTP and RTCP port numbers MUST NOT be the
> same since RTP relies on the port numbers to demultiplex the RTP data and
> RTCP control streams.
> ---------
>
> I have simply removed the SHOULD text, which retains backward compatibility,
> but opens the door for external signaling to use other port numbers.

Removing the SHOULD text makes the text the same as RFC 1889, which
means the requirement level is unstated, not mandatory as you
interpret it to be.  One of the changes required for this new version
was to be more explicit about requirement levels per RFC 2119.  I
don't think the change you suggest will be found acceptable.

							-- Steve

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

---

From: "Paul E. Jones" <[email-masked]>
Date: Sat, 16 Mar 2002 13:35:39 -0500

Stephen,

> don't think the change you suggest will be found acceptable.

That's a fair statement.  So, perhaps we should insert MUST, but then have
the text toward the end of the paragraph remain the same, as it now states
that endpoints MAY "disregard the restrictions that the port numbers be
even/odd" when port numbers are exchanged externally.  We'd need to ensure
that the text makes it clear that both sides must agree to the relaxed
rules.

Paul