Kumar, Hemanth wrote:
> Hi,
>
> I would appreciate if you could answer this.
>
> Regards
> Hemanth
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Kumar,
> Hemanth
> Sent: Friday, April 27, 2007 11:10
> To: [email protected]
> Subject: [Sip-implementors] Regarding Require Header in Session
> Refreshrequests
>
> Hi,
>
> RFC 4028 states that, for the subsequent session refresh requests
> "The values of Supported, Require, and Proxy-Require used in the
> initial Session refresh request MUST be used."
>
> If the subsequent refresh requests does not add any of these headers,
> Would it still use the values in the initial request (initial INVITE)?
If the same entities are still in the call then I would expect that they
would still support the same features. But in general you can't
guarantee that the same entities are in the call. This is especially the
case if there is a B2BUA in the middle of the call.
So it is certainly safer to include these things. The exact results if
they are not included cannot be assured.
> Is the below scenario a valid scenario
>
> ---The initial INVITE carries all these headers and the subsequent
> refresh INVITEs has none of these headers
Its arguable whether this is "valid".
> Why does RFC mandate that these headers must be used in the subsequent
> requests?
In this set of questions you didn't mention Session-Expires or Min-SE.
If you send a reINVITE or UPDATE and don't include Session-Expires, then
what you have done is cancel the session timer.
Paul
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