Jade Chen Yan wrote:
Hi, List,
in RFC 3261,17.1.1
about the INVITE client transaction,if the tranaction comes to the
proceeding state, there is no timer for it. If it cannot receive the
final response, it will be suspended at this state. .I think timerB will
be stop when receivng the 1XX response.
Can any one tell me whether I am right or not?
Right. However, chances are that it will not be suspended forever. The
(human or automaton) user associated with that UAC will eventually tire
of waiting (in case of a human) or time out (in case of an automaton)
and "hang up", thus issuing a CANCEL request and eliciting a 487 final
response. Note that rfc2543 endpoints will not issue a 487 (in fact,
487 response code was not even defined in rfc2543), so your transaction
state machine should be capable of terminating the pending INVITE
transaction after having send CANCEL and getting a 200 OK for it (and
waiting a sufficient amount of time to allow late responses for the
INVITE to come in), or in the worst case, not even getting a 200 OK
for the CANCEL. Take a look at rfc3261 section 9.1 for more details.
Also, proxy processing is a little different for the Proceeding state.
In proxies, a timer C is started and is updated every time a 1xx
response flows through them. Section 16 of rfc3261 outlines this in
detail.
Regards,
- vijay
--
Vijay K. Gurbani vkg@{lucent.com,research.bell-labs.com,acm.org}
Wireless Networks Group/Internet Software and Services
Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm 6G-440
Naperville, Illinois 60566 Voice: +1 630 224 0216
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