Subject: RE: [Sip] B2BUA

From: [email-masked]
Date: Mon, 2 Dec 2002 19:02:57 +0100

Mary,
Debates about what a B2BUA can or cannot do come back regularly. That's why
I suggested that to avoid confusion, the definition needs maybe to be
improved.
See other comments inline in your text.
Best regards
Juan Carlos

"Mary Barnes" <[email-masked]> on 02/12/2002 18:46:48

To:   Juan-Carlos ROJAS/FR/ALCATEL@ALCATEL
cc:   [email-masked]
Subject:  RE: [Sip] B2BUA

Juan-Carlos,

So, I guess you're suggesting that the term "concatenation" is not accurate
or is misleading and I guess that depends upon how loosely one applies the
term concatenation here; my assumption had been that it meant that they
were "linked" (consistent with Webster's definition of concatenate) in some
manner which is unprescribed, so I think your point 2 below isn't a problem
with the current definition.  My understanding of the current definition is
that there isn't anything more for the SIP protocol to prescribe about the
operation of a B2BUA other than what is required from a protocol
perspective to function as a UAC and a UAS. From a protocol perspective, it
is a logical entity and thus whether there's one or multiple doesn't seem
to apply.

JC: you say "...they were "linked" ... in some manner which is
unprescribed". Fully agree with you, and in my feeling, the word
"unprescribed" or any other synonym should be used explicitly in the
definition of a B2BUA (this is not currently the case), because very often
this is the reason of confusion.

I think what you (and perhaps others) are suggesting is that there's a
definition of a B2BUA that more closely parallels the definition of a Proxy
Server since in many cases the physical rendition of the logical B2BUA
functionality would be replacing a Proxy Server in a network. And I think
this is where the problem begins, as many are opposed to this model (as it
increases the complexity, etc.) and this is why the logical definition has
remained.

JC: it is definitely not my case to search for any parallel with the
definition of a Proxy Server (whose behaviour is well defined in RFC3261).
Do mind that this discusion thread started because somebody asked what a
B2BUA can or cannot do. The central problem is once again this
"unprescribed" relation of UAs in a B2BUA.

On your first point, however, I think we need to wait until the
conferencing work in SIPPING is more complete before we can suggest that a
conference server would be a B2BUA.

JC: you can define a conference server as a B2BUA or not, no problem with
that. But this is only one type of application; I'm not suggesting it, I
used only as an example.

Mary.

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip