On Mon, 2009-02-23 at 09:30 -0800, cool goose wrote: > Can someone explain me the importance of CSeq in REGISTER request? RFC 3261 > specifies that UA must increment the CSeq value by one for each REGISTER > request with the same Call-ID. What is the expected response from a > registrar if a UA keeps retransmitting the REGISTER request with same CSeq > value and the same Call-ID?
The registrar will keep a record for several minutes of the REGISTER that it received and the response that it gave to the REGISTER. When it receives a duplicate of the REGISTER, it will send a duplicate of the response, without further processing. (This is necessary because the Internet can duplicate UDP messages, and also to all the sender to re-send if the response gets lost.) After the registrar has purged memory of the REGISTER (with that CSeq), it will most likely respond to further REGISTERs with that CSeq will a 500 "Out of order" response. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
