Subject: [Sip] bis draft: Minor NIT on Supported header

From: "Drage, Keith (Keith)" <[email-masked]>
Date: Fri, 28 Sep 2001 14:10:30 +0100

The current text in bis-04 10.41 for the Supported header says:

   The Supported general-header field enumerates all the capabilities of
   the client or server. This header field SHOULD be included in all
   requests (except ACK) and in all responses.

There would seem to be little point in including this header in a 100 Trying
response, and as I am coming to the conclusion that this is the only header
required to appear apart from the normal mandatory ones, perhaps we should
modify this text slightly to exclude the 100 Trying response.

Does anybody see any purpose for any headers other than From; To; Call-ID;
CSeq; Via; and Content-Length within a 100 Trying response.

Keith
Keith Drage
Lucent Technologies
Tel: +44 1793 776249
Email: [email-masked]

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From: Vijay Gurbani <[email-masked]>
Date: Fri, 28 Sep 2001 08:41:26 -0500

"Drage, Keith (Keith)" wrote:
[...]
> CSeq; Via; and Content-Length within a 100 Trying response.

Yeah. Two headers: Server and Timestamp.

Server identifies the UAS (or proxy) and if the UAC included a Timestamp,
the UAS should probably echo it (I think the bis has a MUST on this).

Regards,

- vijay
-- 
Vijay K. Gurbani  vkg@{lucent.com,research.bell-labs.com,acm.org}
Internet Software and eServices Group 
Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm 6G-440
Naperville, Illinois 60566     Voice: +1 630 224 0216   Fax: +1 630 713 0184

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From: Jonathan Lennox <[email-masked]>
Date: Fri, 28 Sep 2001 14:47:58 -0400 (EDT)

> CSeq; Via; and Content-Length within a 100 Trying response.

In addition to the two Vijay mentioned (Server and Timestamp), I don't see
anything wrong with including Date.  Some servers, including ours, insert it
in every message generated.  (In a 100 it's probably roughly as useful as
Server, i.e. it's good for debugging and for diagnosing various abnormal
situations.)

Bis says that Record-Route headers MAY be present in a provisional response,
and doesn't separate out 100 Trying from other 1xx responses.  I can
imagine scenarios where Record-Route in a 100 could be useful, but I'm not
sure how plausible they are.  

-- 
Jonathan Lennox
[email-masked]