El Thursday 25 October 2007 11:15:41 Klaus Darilion
escribió:
> Iñaki Baz Castillo schrieb:
> > El Tuesday 23 October 2007 14:31:23 Klaus Darilion
escribió:
> >> And what says the RFC about a proxy which does
parallel forking? Then
> >> there may be multiple 180 ringing with
multiple to tags. Which one
> >> should be used?
> >
> > Hi again.
> >
> > Note that RFC 3261 assumes parallel forking in a
different way as OpenSer
> > does. OpenSer just replies **one** final response
to UAC but notes what
> > RFC 3261 says:
>
> I think it does not assume a different way then Openser
- this is just a
> race condition: proxy forwards to A and B. A sends 200.
proxy sends 200
> to caller and CANCEL to B. If B picks up the phone and
sends the 200 OK
> before the CANCEL arrives then the proxy should forward
the 200 OK from
> B to the caller too and the caller has to deal to send
a BYE to one of
> the calls.
>
> Further this race condition is not related to you
CANCEL problem as if
> there is already a 200 OK there will not be a CANCEL
anymore, but a BYE.
Yes, it's different case.
In fact, I'm thinking about this CANCEL problem I can't find
a solution
compliant with that RFC expects, it's just impossible:
RFC says that when UAC sends a CANCEL (with no to_tag) it
must receive a "200
cancelled" with the to_tag of previous 180 or 183
(where there is a to_tag).
But in the other hand, CANCEL is hop by hop related, so the
SIP device that
must reply to that CANCEL is the proxy and not the UAS. If
the proxy
generates various branchs because parallel forking there
could be various 180
with different to_tag, so in case of CANCEL how could
OpenSer reply a 200
with every to_tags the UAC knows? that's why OpenSer replies
with a new
to_tag.
If I'm right in the above explanation (could you confirm
please?) then, what
should we do? open a bug for RFC? XDD
It's clear that Asterisk in pedantic mode (this is: matching
tags) it doesn't
recognize the "200 cancelled" with new tag from
OpenSer. Is it because
being "too much" RFC compliant?
Best regards.
--
Iñaki Baz Castillo
ibc in.ilimit.es
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