[Sip] RFC 3261 - 16.10 (CANCEL processing in a Proxy)

[Iñaki Baz Castillo <[e-mail]>]

Hi, according to RFC 3261 - 16.10 CANCEL Processing (Proxy)

  If a response context is not found, the element does not have any
  knowledge of the request to apply the CANCEL to.  It MUST statelessly
  forward the CANCEL request (it may have statelessly forwarded the
  associated request previously).


In my case I do know that my proxy doesn't behave as a stateless proxy
so I see no reason to forward a CANCEL if it doesn't match a server
transaction. And I do know that such forwarded CANCEL will not success.

I've also told that such requeriment (statelessly forwarding a CANCEL
if not transaction is matched) would never work in some scenarios as
IMS.

Basically, if I do know that my proxy always behaves statefully there
is no use case in forwarding a CANCEL not matching a server
transaction. IMHO such "MUST" in 16.10 should be relaxed and local
policies allowed.

BTW, could an always-stateful proxy reply 481 upon receipt of a CANCEL
not matching a server transaction? or should it ignore it? (this is
not contemplated in RFC 3261 as it mandates statelessly forwarding of
the CANCEL, but I hope such requeriment should be removed/relaxed in a
future revision of SIP protocol).

Thanks a lot.



-- 
Iñaki Baz Castillo
<[e-mail]>