[EMAIL PROTECTED] wrote:
>
> Jonathan R. wrote:
> <snip>
> > Of course, the easier thing is not to bother with loop detection.
>
> A related question :
> If a stateful proxy does not bother with loop detection and
> goes the Max-Forwards way, how does it handle a CANCEL request
> to such a loop. When the caller generates a CANCEL, each stateful
> proxy in the loop sends a 200 OK to the CANCEL, and generates
> one of its own. So, when the stateful proxy receives a CANCEL for
> the first loop, it sends a 200OK and generates one. But when
> it receives the CANCEL for the subsequent loops, how does the
> transaction layer differentiate between this CANCEL and the
> retransmissions of the CANCEL for the first loop. My point is
> that the CANCEL for every leg in the loop looks exactly identical
> (since it contains only one Via header, whose branch is the same)...
No, its not the same. The branch ID in the CANCEL mathces that of the
request being cancelled. Therefore, the CANCEL will be different each
pass through the loop as long as each request has a different branch ID
through the loop, and they should be different based on the rules in
bis.
> Similarly, when a proxy detects the loop and sends a 484, each
> proxy in the loop will send an ACK to the 484 and generate a 484 of
> its own. In this case, when a stateful proxy receives an ACK, how does
> the transaction layer distinguish whether it is a remote retransmission
> for the 484 it sent for the outermost loop (and hence it can be quietly
> ignored), or an ACK to a 484 of an inner loop (in which case the
> retransmissions of the 484 should be stopped). Again the ACK for each
> leg of the loop is identical to the previous, and the transaction layer
> will not be able to match it to a unique transaction.
Same answer as for cancel; see 17.1.1.3 of bis-09.
-Jonathan R.
--
Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Avenue
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.jdrosen.net PH: (973) 952-5000
http://www.dynamicsoft.com
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