On Wed, Jun 30, 2010 at 11:22 AM, Nitin Kapoor <[email protected]> wrote: > Dear All, > > > > I have the issue where an INVITE initiated dialog, the 200 OK of the PRACK > is received after at the UAC than the 200 OK of the initial INVITE provided > that the UAS had sent them in proper order..what should be the behavior of > the UAC? > > > > In this scenario, the UAS had sent the 200 ok of the PRACK followed by the > 200 ok of the INVITE..as it should normally. > > > > As far as I know this may be a possibility in large distributed SIP > networks. SIP only provides a way of determining the next SIP serer hops by > Route headers..and a CSeq header to check the proper sequencing of messages. > However, it does not guarantee what network links should be taken by the > packets to reach the next hop. This is in contrast to SS7, where we have > such provisions at MTP3 layer. > > > > How will the sip stack at the UAC behave if such a situation occurs? Will it > silently drop the packet? Or will it establish the dialog ? Or should it > tear down the session by sending a BYE? > It should send ACK for INVITE 200 OK and should establish the dialog. Both INVITE and PRACK are independent transactions here and the offer/answer has been completed. Even if PRACK is carrying the offer, the INVITE 200 OK will be empty and the answer would be arriving in PRACK response which should not cause any problem. > > > Here is what rfc says.. > > > > ************ > > As per RFC3262, > > > > if any of the unacknowledged reliable provisional responses contained a > session description. UAS must not send 200(INVITE) until those provisional > responses are acknowledged. > > ******************* > > > > Thanks, > > Nitin Kapoor > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >
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