RE: [Sip] Open Issue #7: CANCEL for non-INVITE

> -----Original Message-----
> From: sip-admin@ietf.org [mailto:sip-admin@ietf.org]On
> Behalf Of Gonzalo
> Camarillo
> Hello,
>
> > If that is indeed the choice, then we should remove 1xx
> responses for
> > non-INVITE requests. As long as there are 1xx responses,
> non-INVITE
> > requests can sometimes not complete immediately.
>
> I agree with this. Let's define CANCEL for non-INVITEs as a
> "do nothing"
> on the server side and let's remove 1xx responses for non-INVITEs.

The problem I see here is the difference between complete immidately,
and the ability to cancel before completion. For example this all
started because of REGISTER, sending 100 then attempting to do the
database magic (possibly over a network) makes sense to restrict
retransmission, yet providing full rollback semantics to allow the
REGISTER to cancel is trickier.

>
> Then, for backwards compatibility, my understanding is that
> a "200 OK"
> for a CANCEL just means "I have received the CANCEL. You can stop
> retransmitting it". It does not imply that we are trying to cancel
> anything. In fact, if a UAS responds with a 2xx an INVITE
> request and
> later it receives a CANCEL, it still answers the CANCEL
> with a 200 OK.
>
> Therefore, if an old UAC still sends a CANCEL for a
> non-INVITE request,
> a "200 OK" response for the CANCEL seems appropriate to me.

I'd agree with this just not getting rid of 100s for non-INVITEs

James Undery

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