james jack wrote:
>
> Dear All:
> I have one question to ask, the situation is listed
> as the following:
> User A call User B via Proxy P, User B has three
> contact address in the registrar whose domain is the
> same as that of the proxy P. So when User A send
> INVITE request to User B, this INVITE request will be
> forked into three branches,the INVITE request will
> reached User B(1),B(2),B(3). the demonstration diagram
> is listed as the following:
>
>
> B(1)
> A---- P -------B(2)
> B(3)
> When B(1) receives INVITE request, without sending
> 100 response, B(1) sends BYE request to this INVITE
> requst, when this request arrives P, according to the
> CallLeg, it can match, then what would Proxy P do?
> Wait for other B(2),B(3)'s response? Or delete the
> corresponding State machine in P? or throw this BYE
> request?
James:
I have a hard time figuring out why a UAS would respond to an
INVITE with a BYE without sending any provisional and/or final
responses to the INVITE first. The RFC makes it pretty clear
that (a) an INVITE elicits a provisional and/or a final response,
and (b) a BYE tears down a session previously established; in
this case, a session has not been established between B(1) and A.
However, if B(1) sends a BYE to P, the BYE will match the
"default call leg" i.e. From (maybe with tags), Call-ID, and To
(definitely no tags since B(1) never send out a final response
to the INVITE). Since proxy P knows that it has responses to
two other INVITE pending, it must wait until it gets a "better"
response from one of the other UASes.
- vijay
--
Vijay K. Gurbani vkg@{lucent.com,research.bell-labs.com,acm.org}
Internet Software/IN Architecture Group
Lucent Technologies/Bell Labs Innovations 263 Shuman Blvd., Rm 1A-413
Naperville, Illinois 60566 Voice: +1 630 224 0216 Fax: +1 630 713
0184
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