Hi,
it is clear what to do when initiating a session using an INVITE with Expires
header... but some questions remain (at the end of this mail).
[from RFC 3261]
13.2 UAC Processing
13.2.1 Creating the Initial INVITE
[...]
The UAC MAY add an Expires header field (Section 20.19) to limit the
validity of the invitation. If the time indicated in the Expires
header field is reached and no final answer for the INVITE has been
received, the UAC core SHOULD generate a CANCEL request for the
INVITE, as per Section 9.
13.3 UAS Processing
13.3.1 Processing of the INVITE
[...]
1. If the request is an INVITE that contains an Expires header
field, the UAS core sets a timer for the number of seconds
indicated in the header field value. When the timer fires, the
invitation is considered to be expired. If the invitation
expires before the UAS has generated a final response, a 487
(Request Terminated) response SHOULD be generated.
This means:
UAC-------------->UAS
INVITE B
Expires: 30
UAC<--------------UAS
100
after 30 seconds
UAC-------------->UAS
CANCEL
[200 CANCEL, 487 INVITE, ACK]
so probably at UAS side, the timer never fires because UAC sets his timer when
sending and UAS when receiving.
Why both UAC and UAS have to set the timer to take future actions?
Wouldn't be better if only B set the timer so that no CANCEL is needed?
Thanks.
--
Marco Ambu
R&D Software Engineering
Abbeynet S.p.A. - www.abbeynet.com <http://www.abbeynet.com>
Phone: +390702339331
Call me for free: <http://www.marco-ambu.sitofono.it>
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