> From: Anil Bollineni [EMAIL PROTECTED] > I want to talk about NAT firewall. If two UA's behind NAT firewall generate same > branch, and NAT ALG will change the VIA sent-by field to same value. In this > case it could result matching same transaction.
True. Which is why UAs should generate branch parameters that are unique over all space and time, that is, include some identifier of the UA itself to ensure that no other UA will generate the same branch parameter. > I understand for retransmitted non-INVITE requests it MUST result sending same > response by UAS > What is the purpose behind that. It is to ensure that the retransmission of the request provokes a "pure retransmission" of the response. In particular (1) the UAC does not attempt to re-execute the request if it receives it twice (which might cause erroneous operation), and (2) if the response to the first request is only delayed, and the UAC receives both the first response and the second response, both responses are identical (otherwise, how would you process them both?). Dale
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