Scott is correct. The next CSeq is 4.
-Jonathan R.
> -----Original Message-----
> From: Scott Happell [mailto:[EMAIL PROTECTED]]
> Sent: Monday, February 12, 2001 6:45 PM
> To: 'Venkatesh Venkataramanan'; Scott Happell
> Cc: [EMAIL PROTECTED]
> Subject: RE: [Sip-implementors] RE: [SIP] Question regarding CSEQ
> processi ng with PRACK...
>
>
> The CSeq counter should increase for each successive transaction in a
> particular direction. In this case the Client sending to the
> Server. The
> CSeq of the BYE should be 4. The PRACK transaction(s) are separate
> transactions. they just happen to take place smack in the
> middle of the
> INVITE transaction.
>
> Note that you can still send the final response to the INVITE
> before the
> PRACK receives a final response. If the CSeq of the BYE was 2
> instead of 4,
> you could potentially have transactions within the same call
> leg, with the
> same CSeq(PRACK and BYE). This would cause a
> "transaction-clash" according
> to the rules of matching requests to transactions in Section
> 11.5 of the
> bis2 draft. More specifically, the BYE would be treated as a
> retransmission.
>
>
> -----Original Message-----
> From: Venkatesh Venkataramanan
> [mailto:[EMAIL PROTECTED]]
> Sent: Monday, February 12, 2001 5:00 PM
> To: Scott Happell
> Cc: [EMAIL PROTECTED]
> Subject: RE: [Sip-implementors] RE: [SIP] Question regarding CSEQ
> processi ng with PRACK...
>
>
> I guess I didn't state my question correctly. Following call scenario:
>
> 1. UAC sends an INVITE with CSEQ 1.
> 2. UAS responds with 183 SESSION PROGRESS (CSEQ=1).
> 3. UAC creates a PRACK with CSEQ=2.
> 4. UAS responds with a 200 OK (for PRACK, CSEQ 2).
> 5. UAS sends another provisional response 180 RINGING (CSEQ = 1).
> 6. UAC creates another PRACK with CSEQ=3.
> 7. UAS acks the PRACK.
> 8. UAS sends a 200 OK (for INVITE, CSEQ=1).
> 9. UAC sends a ACK (for INVITE) completing the 3 way handshake.
>
> At some point one of them decide to hangup. A BYE is issued.
> What shd the
> CSEQ be ? Should be 4 (basically greater than the CSEQ of the
> last PRACK)?
> or can it be 2(basically greater than the CSEQ in the last INVITE)?
>
> The doc says that the CSEQ MUST be greater than the last completed
> transaction. In the above call flow, the INVITE is the last completed
> transaction and the CSEQ for the same was 1.....
>
> Thanks,
> Venkatesh
>
---
Jonathan D. Rosenberg 72 Eagle Rock Ave.
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.cs.columbia.edu/~jdrosen PHONE: (973) 952-5000
http://www.dynamicsoft.com
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