Comments inline...
Regards,
Nataraju A B
Sonus Networks Ind Pvt Ltd
> -----Original Message-----
> From: [EMAIL PROTECTED]
[mailto:sip-implementors-
> [EMAIL PROTECTED] On Behalf Of Gardell, Steven
> Sent: Friday, September 01, 2006 1:19 AM
> To: [EMAIL PROTECTED]
> Cc: sip-implementors@cs.columbia.edu
> Subject: Re: [Sip-implementors] Implied "supported:"
>
> The language of 3261 20.37 says "supported:" "Enumerates all
extensions"
> and goes on to say that "supported:" with an empty list means
> "no extensions." This seems pretty explicit to me.
> Hence there is in some sense a logical contradiction between
> having a "supported:" header present without "session-expires" and
> also seeing the "session-expires" header.
>
> All the same the notion of implying UAC support for
> session-expires via is presense as a header (as you infer)
> is clearly the intuitive and almost certainly the
> preferable approach. The alternative of returning an error
> seems rather unfriendly and uncessesary unless it is
> demanded by the protocol. I certainly don't see that specified...
>
[ABN] I agree, responding with error response is not a good idea. But I
feel we should have not considered session-timer for this session. If
start doing so, then the need for Supported header would be under-used.
Also if we do this, the implementations would need to lot more
checks against all the new extensions, which does not look good (at
least to me and many more also)
The best option would be to don't consider any extensions which are not
mentioned in Supported/Require header, this makes your implementation
pretty simple and cleaner also...
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of
> [EMAIL PROTECTED]
> Sent: Thursday, August 31, 2006 2:37 PM
> To: sip-implementors@cs.columbia.edu
> Subject: Re: [Sip-implementors] Implied "supported:"
>
> From: "Gardell, Steven" <[EMAIL PROTECTED]>
>
> What is the correct procedure for a UAS to evaluate client
> support for an extension that is explicitly present as a header
> in a request. For example if an INVITE contains a
> "session-expires:" header, should it/must it also provide
> the corresponding "supported:" field.
>
> The Supported header is an explicit declaration that the UA supports
the
> extensions it lists. But absense of Supported is not positive
evidence
> that the UA does not support the extension.
>
> But if a UAS needs to consider whether the UAC supports a particular
> extension in order to formulate a response, the designers of the
> extension have usually thought through what the UAS should do.
>
> What is the case you're worrying about?
>
> Dale
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