Now your back to restricting what I can and can't do in an intermediary. It can't be a B2BUA 'cos it doesn't need to honour require headers (the UA at the other end does that, if they were meant for my intermediary then they would be proxy-require?), and it can't be a proxy 'cos of the rules about not changing the body so what is it?
It's not sanctioned by the RFC, yet id does an important and useful job.
-----Original Message-----
From: Adam Roach [mailto:adam@dynamicsoft.com]
Sent: 04 December 2002 00:37
To: 'Padma Suresh'; vkg@lucent.com; pete@tech-know-ware.com
Cc: sip@ietf.org
Subject: RE: [Sip] B2BUA & Max-Forwards
-----Original Message-----
From: Padma Suresh [mailto:padma_suresh@hotmail.com]
> A B2BUA needs to propagate some of the headers received in a
> request/response to the other endpoint. Example: Require...
No. As emphatically as possible: NO. This is completely wrong, and it appears to be a growing -- and dangerous -- misconception.
A B2BUA cannot transparently pass Require through. It must understand and invoke the extension indicated.
"The Require header field contains a list of option tags, described in
Section 19.2. Each option tag defines a SIP extension that MUST be
understood to process the request."
A back to back user agent *is* a UAS, and *is* bound by this provision.
Whether the UAC portion then turns around and imposes the same requirement on the UAS it contacts is a local decision.
/a
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