On 7/15/14 7:07 AM, Brett Tate wrote:
Can there be any case when CANCEL reached to UA2
before INVITE in case od UDP? because the 100 trying
can be sent by proxies as well.
Yes, 100 is sent hop by hop. But CANCEL is itself also hop by hop. So at
each hop the cancel is only sent if a 1xx has been received from downstream.
Yes (although no longer as common); as mentioned within RFC 3261 section
28.1, RFC 2543 did not have the same mandate as RFC 3261.
"o A UA or proxy cannot send CANCEL for a transaction until it gets a
provisional response for the request. This was allowed in RFC
2543 but leads to potential race conditions."
I guess Brett is saying that it can only happen if there is a device on
the path that supports 2543 and not 3261. I hope there are no longer any
of those deployed.
Thanks,
Paul
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