Sudipta Ghosh wrote:
Hi, I have one doubt regarding Transaction Layer. According to SIP RFC 3261.Transaction Layer retransmits sip request if it doesnt get the response for that method. The rule of re-transmission is given in RFC. After certain time Transaction Layer will inform the Transaction User(TU) about timeout. Now my question are. 1.A UAC will retransmit a request to proxy if it didnt get the response. Proxy will retransmit the request to UAS. (If the UAS is in the same domian)
It has nothing to do with being in the same domain.
Right. In the case of INVITE the proxy and UAS would both generate a 1xx which would terminate retransmissions though.In proxy retransmission of request will be made form its Transaction Layer but proxy will receive the same request from UAC.
If the proxy is transaction stateful, it does nothing. THe receipt of a retransmitted request does not trigger it to send another request.What Proxy will do when it gets same request from UAC?
Transactions are defined between stateful elements, which includes proxies. Forking is impossible without it, many features are impossible without it. Its also better in terms of retransmits since it reduces the effective RTT seen by the UAC.Why retransmission of request is also included in PROXY?(UAC retransmits a request if it doesnt get the response)
-Jonathan R.
--
Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Ave.
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dynamicsoft East Hanover, NJ 07936
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