Hi,
> Thanks much for your reply.
> Following are some more queries about this.
> 1. Since user A maintains 2 dialogs before it sends CANCEL msg.
> When should it remove these 2 dialog informations?
> If proxy P just forward one 487 msg to user A, will user A just remove
> one dialog?
User A maintains two dialogs only if the provisional responses arrived
with a To tag. Otherwise an early dialog does not get established.
In either case, all early dialogs are considered terminated on receiving
the 487 response (Ref line 2156 bis-09).
> 2. If proxy P sends 200 immediately, what To tag should it choose?
This is upto the proxy. If the proxy decides to generate and insert a To
tag of its own in the 200-CANCEL, it should ensure that the same is
inserted
in the 487 that it forwards upstream. Else it could send a 200 to the
CANCEL without a To tag (To tag insertion in 200-CANCEL is a SHOULD). Ref
line 2917-2922 of bis-09 for more on this.
> 3. If it doesn't not send 200 immediately, when should it send the 200
msg,
> after receiving both 200 msgs from b1 and b2?
> And what To tag should it choose?
It should send the 200 immediately as the CANCEL is hop by hop and should
be
acknowledged immediately in order to prevent its time out due to late
responses
from b1 and b2.
Regards,
Subhash Nayak
Hughes Software Systems
http://www.hssworld.com
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