Supported and Require are not formally linked.
For some options you can infer a logical connection.
When in doubt, be explicit.
Also note that Require:xyz means "I require you to *support* xyz". It
does not mean "I require you to *use* xyz" or "I intend to use xyz".
Thanks,
Paul
On 6/24/2011 1:34 AM, Harbhanu wrote:
> Hi,
> As per 3261, the text for Supported and Require is as below-
>
> Supported:
> If the UAC supports extensions to SIP that can be applied by the
> server to the response, the UAC SHOULD include a Supported header
> field in the request listing the option tags (Section 19.2) for those
> extensions.
>
> Require:
> If the UAC wishes to insist that a UAS understand an extension that
> the UAC will apply to the request in order to process the request, it
> MUST insert a Require header field into the request listing the
> option tag for that extension.
>
> Is it valid to interpret that an extension present in 'Require' is also
> 'Supported' by
> the UAC?
> In other words, is it mandatory to put an extension in both headers, incase
> 'Require' is used for any extension?
> This becomes bit confusing, since any Proxy 'MAY' put 'Require' in the
> message.
>
> As per my opinion these two should be explicitly carry the extension,
> because of the proxy case.
>
> Please share your opinion. Thanks!
>
> Regards,
> Harbhanu
>
>
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