Re: [Sip] B2BUA & Max-Forwards

[Juan-Carlos.Rojas@alcatel.fr]

Hello,

The following text comes from RFC 3261, page 39
"A UAC MUST insert a Max-Forwards header field into each request it
originates with a value that SHOULD be 70"

Now, a B2BUA handles several UAs.
For a given UA, when behaving as UAC, the Max-Forwards header has to be
*initialised* by the UA. The RFC3261 recommends to use the value 70, but
this is not mandatory (to fixe the initial value of Max-Forwards, RFC3261
uses a SHOULD and not a MUST).

Therefore, a B2BUA acting as an application can freely choose for a UAC
which it is handling:
- Initialise Max-Forwards to 70, as recommended by RFC3261 for a UAC
- Initialise Max-Forwards with the value possibly received in a UA acting
as UAS.
- Initialise Max-Forwards to any other value, according to the application
definition

Once again, this is a question of application defintion.

Best regards
Juan Carlos





"Pete Cordell" <pete@tech-know-ware.com>@ietf.org on 03/12/2002 18:44:21

Sent by:  sip-admin@ietf.org


To:   <sip@ietf.org>
cc:
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.

Any comments?

Pete.



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_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors@cs.columbia.edu for questions on current sip
Use sipping@ietf.org for new developments on the application of sip