Comments inline…
Thanks & Regards,
Nataraju A.B.
-----Original Message-----
From:
[EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Sushil Kumar Verma
Sent: Friday, March 05, 2004 10:16
PM
To:
[EMAIL PROTECTED]
Subject: [Sip-implementors] race
condition
Please help me for the following race condition
scenario...
|---------------------------->|------------------------->|
|<----------------------------|<-------------------------|
| CANCEL 200
|<-------------------------|
|---------> <---------| (race
condition) |
| <------------
|
|
|
CANCEL |
|
| ------------>|
|
|
|
|
|
|
|
|
|
|
When a UA1 sends INVITE to a B2BUA (or statefull Proxy)
which than forwards it to UA2.
UA2 answers by sending 200 OK which B2BUA forwards to UA1
, but before receiving 200 OK UA1 sends CANCEL. In that case
Q1.What will UA1 do when he receives 200 OK after
sending CANCEL?
[ABN] accept it
as a valid incoming message… but respond back with failure response.
Will UA1 ignore 200 OK or will he send
some 4xx (say 403) response for CANCEL?
[ABN] Yes, forwards
2xx-INV and send failure response to CANCEL
Q2.What should B2BUA do ? Should he send CANCEL to
UA2 or he should send ACK (for INVITE) and than BYE to UA2?
[ABN] NO, It
would not send the CANCEL to UA2. but sends failure response to CANCEL…
Q3. WHat will a terminating UA2 do if he sends 200 OK
and immidiatly after that receives CANCEL (rather than getting ACK)?
[ABN] reject
the CANCEL with failure response..
Will B2BUA (or statefull proxy ) accept CANCLE after
sending 200 OK(answer) and forwards it to termitaing UA?
or it will send 200 OK (for CANCEL) and 487
Response(for INVITE) to UA1 and on the other side It will send ACK(for
INVITE) and then send BYE to UA2?
[ABN] it will
reject CANCEL with a failure response…
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