Re: [rtcweb] How to multiplex between peers

[Stephan Wenger <[e-mail]>]

Hi Colin,

On 7.21.2011 01:25 , "Colin Perkins" <[e-mail]> wrote:

>[...]
>
>> Now to my key point: you argue these things need to be "carefully
>>evaluated" in AVTCORE. IMO, while it may be desirable for AVTCORE
>>experts to chip in (as they do on this very thread already:-), it is by
>>no means necessary.  Neither formally, not practically.  And certainly
>>AVTCORE should not assume a "blocking" position.  This puts IETF system
>>level specification at a disadvantage to system level specification work
>>elsewhere (where it happens on a daily basis, see ITU, see 3GPP), and
>>where no one asks for AVTCORE's permission to re-use RTP data structures
>>without re-using all of RTP.  Tinkering with the multicast functionally
>>of RTP is not new, there is a lot of implementation experience in the
>>field, and for once we can indeed rely on "running code" answers.
>> 
>> I advocate pragmatism. (And, heretic as I am, in the long term we
>>should think about RTPv3, dumping multicast.  Have I said this before?
>>:-)
>
>You have, of course. Many people have. What's not clear to be is how you
>would remove multicast support from RTP without also removing multiparty
>support? I see lots of RTP features that are there to support group
>communication, very few that are specific to multicast.

Remove multiparty support, then.  Terminology glitch on my side.

>
>And, besides, I can certainly envisage scenarios where one might want a
>browser-based RTP implementation to watch the multicast IPTV flows that
>ISPs are now offering.

There is no reason why RTPv2 and RTPv3 couldn't co-exist, in a browser or
elsewhere.  They do, today, if you have a videoconferencing software and
an IPTV software on the same box.

It would be stupid to deprecate RTPv2 including multiparty support; no one
I know is arguing in favor of that.

Problem is, AVT (and, admittedly, the industry at large) did not act on
the RTPv3 idea.  Instead, application spec profiling continued with many
(dozens?  I lost count a long time ago) of non-interoperabile solutions
for the optimized-for-point-to-point RTP space.  (To a certain extent that
even happens in the multiparty case with different IPTV standards.) We are
about to create one more P2P RTP flavor here.  That's sad, but (I fear)
now unavoidable.  From what I gather, people don't think we can wait half
a decade for an RTPv3 proposal to make it through an AVT-to-be-named WG.

Stephan

> 
>
>Colin