Subject: [SIP] UDP support changed from SHOULD to MUST

From: Lawrence Conroy <[email-masked]>
Date: Sun, 4 Jun 2000 14:47:20 +0100

*	UDP support changed from SHOULD to MUST in SIP 2453 bis draft.
It looks like support for UDP is gradually moving from a SHOULD to a 
MUST in SIP.

In PINT we may not have that assumption. We can have a good reason 
for using TCP only (inline content, security using TLS, ...), so *for 
PINT* I'd prefer to leave this as a SHOULD.

I wonder if the move to a MUST in the core spec will cause grief for 
any other extension or application.

The key point here is ->in the core spec<-

I had the same feeling at the Interim meeting in D.C. when the 
subject of "Busy Line Verification" was raised - there's a lot of 
focus on VoIP, when I can easily imagine SIP being used for a much 
wider set of applications even for "straight" conferences; for 
example, Quake, as Dean suggests.
Let's imagine an Operator listening in on the sampled Quake audio 
track that I'm conferencing. How long before the Police arrive? An 
over-emphasis on VoIP can lead to bad assumptions, IMHO - SIP is much 
wider than that.
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From: Jonathan Rosenberg <[email-masked]>
Date: Sun, 04 Jun 2000 22:57:36 -0400

> It looks like support for UDP is gradually moving from a SHOULD to a

It was to solve the sticky situation that without at least a common
transport, UA to UA communication would not be possible. It would
require proxies that do conversions to record-route, and all kinds of
other stuff. Simply stating that everyone needs to use UDP made things
much easier, and in any case, I suspect nearly everyone does UDP anyway.
However, please shout if this change is not a happy one for you....

In the case of pint, I would simply suggest that all pint
implementations MUST support TCP as well, in which case you won't have a
problem. Yes, you'll have to do UDP also to be compliant to the baseline
spec, but it turns out that supporting both is really not that hard if
done properly.

> example, Quake, as Dean suggests.

This change has exactly zero to do with telephony. Its as simple as UA
to UA communication not being always possible without a common baseline
transport.

-Jonathan R.
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From: Alec Brusilovsky <[email-masked]>
Date: Fri, 09 Jun 2000 14:28:53 -0500

Please see my comments inline.

Regards,
Alec

> PINT* I'd prefer to leave this as a SHOULD.

I would like to add to what Lawrence is saying that some SIP applications
might need a more flexible and rapid session set up than others. PINT is a
good example, SPIRITS might as well be another one, assuming that the WG
will decide to use SIP.

> The key point here is ->in the core spec<-

Looks like the core spec. needs to be more accommodating to the needs of
extensions (PINT). SHOULD is just fine. Why break something that actually
works?

> PINT mailing list
> [email-masked]
> http://lists.bell-labs.com/mailman/listinfo/pint

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From: Jonathan Rosenberg <[email-masked]>
Date: Sat, 10 Jun 2000 00:29:09 -0400

> good example, SPIRITS might as well be another one, assuming that the WG

Right; both UDP and TCP are still there. You can still do TCP if you
want, or just UDP, but just not ONLY TCP.

> extensions (PINT). SHOULD is just fine. Why break something that actually

Because it doesn't - thats the problem. UA to UA interoperability is not
possible in all cases unless there is a baseline transport. The "core
spec" must be a workable protocol in its own right, without
clarifications and specifics being defined only in extensions, as pint
is.

-Jonathan R.