Both the Options are Wrong....
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Matthew
Gardiner
Sent: Wednesday, February 15, 2006 1:02 PM
To: 'Neeraj Chowdhury'; '[EMAIL PROTECTED]'
Cc: Sip-Implementors
Subject: Re: [Sip-implementors] Local CSeq number after PRACK
Thanks people,
Matthew Gardiner
-----Original Message-----
From: Neeraj Chowdhury [mailto:[EMAIL PROTECTED]
Sent: 15 February 2006 07:06
To: [EMAIL PROTECTED]
Cc: Sip-Implementors
Subject: Re: [Sip-implementors] Local CSeq number after PRACK
Hi
Obviously Option 2 is appropriate //
The Reason : Every UA must increment the numeric part of the CSeq for
each new request send by it except for ACK and CANCEL // As all the
requests as shown are in a single direction the CSeq must be incremented
by the UA //
With thanks
Neeraj Chowdhury
On 2/15/06, Parveen Jain < [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> > wrote:
Hi Matthew,
The CSeq counter should increase for each successive transaction in a
particular direction. The PRACK transaction(s) are separate
transactions. they just happen to take place smack in the middle of the
INVITE transaction.
So the option2 should be correct.
For more clarification follow these links:
http://lists.cs.columbia.edu/pipermail/sip-implementors/2001-February/00
<http://lists.cs.columbia.edu/pipermail/sip-implementors/2001-February/0
0>
0440.html
http://lists.cs.columbia.edu/pipermail/sip-implementors/2005-September/0
<http://lists.cs.columbia.edu/pipermail/sip-implementors/2005-September/
0>
10195.html
Hope this helps.
Regards,
Parveen
-----Original Message-----
From: [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
[mailto: [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> ] On Behalf Of Matthew
Gardiner
Sent: Tuesday, February 14, 2006 4:32 PM
To: Sip-Implementors
Subject: [Sip-implementors] Local CSeq number after PRACK
Hi all,
I apologise if this question has already been asked in the
sip-implementors group. If so, I have either lost or missed the relevant
mails and I would be happy if someone could point out the relevant links
to me.
However, the question is as follows: When a PRACK is sent to acknowledge
a provisional response should the caller's local CSeq assume the value
of the "outer" INVITE transaction or that of the PRACK transaction,
regarding the CSeq to be referred to in future requests by the caller.
For example consider a simple call, with 100rel, which is setup and then
torn down by the caller.
Option 1) Local CSeq retains value of CSeq in INVITE after dialog
establishment
--> INVITE CSeq 1
<-- 180 CSeq 1
--> PRACK CSeq 2
<-- 200 CSeq 2 PRACK
<-- 200 CSeq 1 INVITE
--> ACK CSeq 1
... media ... (no intervening SIP messages) ...
--> BYE CSeq 2
<-- 200 CSeq 2 BYE
Option 2) Local CSeq uses value of CSeq in the PRACK after dialog
establishment
--> INVITE CSeq 1
<-- 180 CSeq 1
--> PRACK CSeq 2
<-- 200 CSeq 2 PRACK
<-- 200 CSeq 1 INVITE
--> ACK CSeq 1
... media ... (no intervening SIP messages) ...
--> BYE CSeq 3
<-- 200 CSeq 3 BYE
Hence the CSeq published in the BYE in Option 2) is 1 more than that
used in
Option 1) as it comes from the PRACK's CSeq, which was itself
incremented
after the INVITE.
My interpretation of RFC 3261 and 3262, suggest that Option 2), i.e. the
local CSeq is updated with the CSeq used in the PRACK is correct.
However my
experience of other vendor's equipment suggests that opinions vary.
RFC 3262 states that the "PRACK is like any other non-INVITE request
within
a dialog" and hence the local CSeq should be incremented by 1.
All feedback welcome,
Matthew Gardiner
Software Enginneer
Aculab
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--
With thanks
Neeraj Chowdhury
"To err is human, to find a bug, Devine."
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