Re: [Sip] B2BUA & Max-Forwards

Vijay,

You are right -

A B2BUA needs to propagate some of the headers received in a request/response to the other endpoint.

Example: Require, Expires to name a few. This is because these headers actually are relevant end to end.

However, some of the other headers like Contact should be set by the B2BUA as itself.

Padma

>From: "Vijay K. Gurbani"

>To: Pete Cordell

>CC: sip@ietf.org

>Subject: Re: [Sip] B2BUA & Max-Forwards

>Date: Tue, 03 Dec 2002 15:11:37 -0600

>Pete Cordell wrote:

>>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.

>I have a feeling that specialized handling of headers for B2BUAs is

>yet

>another nightmare in the making.

>A B2BUA is a UA, period. So long as the request made it to one half

>of the B2BUA before Max-Forwards reached 0, the protocol constraints

>on that request have been satisfied. What the other half of the

>B2BUA wants to do with the Max-Forwards header is entirely up to it.

>Regards,

>- vijay

>--

>Vijay K. Gurbani vkg@{lucent.com,research.bell-labs.com,acm.org}

>Wireless Networks Group/Internet Software and Services

>Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm

>6G-440

>Naperville, Illinois 60566 Voice: +1 630 224 0216

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