[SR-Users] TM clarifications Re: CANCEL before INVITE + loose_route()

Iñaki Baz Castillo ibc at aliax.net
Mon Jun 21 10:07:21 CEST 2010


2010/6/21 Alex Balashov <abalashov at evaristesys.com>:
> Thank you for the clarification.
>
> This is what I thought, but I wondered because philosophically it seems to
> slightly conflict with the requirement that the proxy - even a stateful
> proxy - forward what it receives more or less straightforwardly

Well, the proxy did already forward the INVITE request, but such
action implies an outgoing transaction generated by the proxy, with
same rules as any client transaction, including the CANCEL processing
(no CANCEL can be sent if no 1xx has been received for the outgoing
transaction).

Also note that CANCEL is hop-by-hop (in stateful mode), this is: a
CANCEL is not relayed/forwarded by a proxy, but consumed/accepted by
the proxy (so it immediately replies 200) and then the proxy must
terminate *its* pending outgoing transactions (which would involve
*generating* CANCEL requests for those transactions which already
replied a 1xx).




-- 
Iñaki Baz Castillo
<ibc at aliax.net>



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