Server has to treat it as a re-transmission and re-send the previous response.
-----Original Message----- From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of Chaim Geretz Sent: Thursday, September 04, 2014 7:56 PM To: sip-implementors@lists.cs.columbia.edu Subject: [Sip-implementors] REGISTER re-transmission Greetings, Consider a case where the response to a REGISTER gets lost, UA resends the identical request. This means the callid and cseq remain the same. RFC 3261 10.3 (step 7) states that if callid is identical: ... the registrar compares the CSeq value. If the value is higher than that of the existing binding, it MUST update or remove the binding as above. If not, the update MUST be aborted and the request fails. This algorithm ensures that out-of-order requests from the same UA are ignored. ​Since CSeq is not higher than that of the existing binding, this also results in the retries to get ignored as well. Is the the client expected to increment CSeq if a response is not received, or is the server expected to detect re-transmissions and resend the previously sent response prior to applying the algorithm described in 10.3. Thank You Chaim Geretz _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
