Subject: RE: [Sip] B2BUA

From: [email-masked]
Date: Mon, 2 Dec 2002 18:19:43 +0100

Hello,
Well, if from times to times there are questions and debates on a given
subject, it is surely because the definition needs to be improved, or at
least clarified.

"Since it is a concatenation of a UAC and UAS"
1.- A B2BUA is not a "concatenation of a UAC and UAS", but a collection of
several UAs (two, three or more), which behave individually as UAS or UAC
according to SIP rules (and are seen as such from the outside of the
B2BUA). For example, a conference server where all the participants send
INVITE messages to the server could be made with UAS only (do note that
this is strictly a matter of application definition, and cannot be subject
to standardisation).
2.- UAs are not "concateneted" in the B2BUA, but they are linked by some
application logic which is by definition, a non-standard element. This is
the key element that should be precised in the RFC3261 to avoid confusion.
You cannot define the behaviour of a B2BUA, you can define only the
behaviour of each UA (and this is actually done by the SIP specification).

Hoping this answers your questions
Best regards
Juan Carlos

"Mary Barnes" <[email-masked]>@ietf.org on 02/12/2002 17:53:50

Sent by:  [email-masked]

To:   "'Phil Reynolds'" <[email-masked]>, [email-masked]
cc:
Subject:  RE: [Sip] B2BUA

Hi all,

I guess I have to ask, what's the problem with the definition in RFC 3261?

Back-to-Back user agent: A back-to-back user agent (B2BUA) is a
             logical entity that receives a request, and processes it as
             a UAS. In order to determine how the request should be
             answered, it acts as a UAC and generates requests. Unlike a
             proxy server, it maintains dialog state, and must
             participate in all requests sent on the dialogs it has
             established. Since it is a concatenation of a UAC and UAS,
             no explicit definitions are needed for its behavior.

Regards,
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