RE: [Sip] B2BUA & Max-Forwards

["Roy, Radhika R, ALASO" <rrroy@att.com>]

inline [RRR]

-----Original Message-----
From: Pete Cordell [mailto:pete@tech-know-ware.com]
Sent: Tuesday, December 03, 2002 12:44 PM
To: sip@ietf.org
Subject: [Sip] B2BUA & Max-Forwards


One issue that the recent B2BUA discussion has raised in my mind is what a
B2BUA (whatever its decided that should be) should do with Max-Forwards.

This may have been discussed before, but while RFC 3261 says a B2BUA is a
back to back UAS / UAC, and the coupling is not specified in the RFC,
perhaps it ought to say that the max-forwards parameter MUST be propagated
from the incoming request to the outgoing request using the same rules as a
regular proxy.  This would seem helpful for the avoidance of loops.

[RRR] It depends. Proxy MUST abide by its own rules as specified in RFC 3261. Similarly, UAs also MUST need to obey all SIP rules. These two (i.e., Proxy and B2BUA) act independently as per their SIP rules. The question then comes: How do people build services/applications that have the dependency between B2BUA and proxy function? SIP does not define these rules. That is why, people are coming to the conclusion let there should an informational RFC in defining B2BUA functionalities along with call flows (as Brain and others pointed out).

Any comments?

Pete.

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