[SIPForum-discussion] CANCEL with reliable response ...
abhishek chattopadhyay
abchatto at cisco.com
Fri Jun 4 09:51:03 UTC 2010
Hi,
I have the following thought regarding this.
The generation of the PRACK Request can't be estimated by any implementation
as the generation of this is an automated one (depending on availability of
100rel support) where as the CANCEL request is generally generated due to
manual intervention. So probably there might not be a concrete way to have a
procedure for that handling. Moreover there might be implementations that
are capable of forming the event based request (using multiple threads) and
using the transaction state machine to forward it to the network. So even
the prevention from formation of the PRACK message is not always achievable.
Overall the flow that is provided in the question, seems fine to me, and
according to me also complies to the 3261 standards.
(There are few points to observe.)
Cancel transaction terminates the INVITE gracefully. But Cancel transaction
would complete only after the reception of a 200 OK message is received or
the entire transaction is deleted forcefully(which-ever is earlier). Since
the INVITE transaction would be complete with the sending of the final ACK
(final ACK --> which stops re-transmission of the final response), so within
the transaction timeline even if the 180 ringing is received, it is up-to
the design to continue with the rest of the messaging(with the knowledge
that the session has already been requested for Cancellation). So here the
implementation decides to continue with the rest of the messaging till the
INVITE transaction is complete.
But I must say that is a wastage of the processing power of the UA as we
already know the fate of the transaction.
Thanks
Abhishek Chattopadhyay.
Message: 1
Date: Thu, 3 Jun 2010 09:21:43 +0530
From: <sunilkumar.verma at wipro.com>
Subject: Re: [SIPForum-discussion] CANCEL with reliable response ...
To: <mvuppand at cisco.com>, <discussion at sipforum.org>
Message-ID:
<B967EC1195898E499CC20A68744650070B3FA416 at BLR-EC-MBX02.wipro.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
I don't think there is any direct indication in RFC for this sequence.
As per the below notes from RFC 3261 i think terminating Invite transaction
immediately will be the best way out.
I think the side sending the PRACK also must not have sent PRACK, else
waited for PRACK transaction to complete, before sending cancel.
" If the UAS has not issued a final response
for the original request, its behavior depends on the method of the
original request. If the original request was an INVITE, the UAS
SHOULD immediately respond to the INVITE with a 487 (Request
Terminated). A CANCEL request has no impact on the processing of
transactions with any other method defined in this specification."
Regards
Sunil Verma
ESN: 877-5050
Ph: +919731245000
________________________________
From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Murali Vuppandla
Sent: Wednesday, June 02, 2010 6:33 PM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] CANCEL with reliable response ...
There are two SIP nodes A and B. A sends an INVITE with 100rel tag in
Supported header. B sends 180 reliably with 100rel in Require header. A
would like to CANCEL the call at this particular point of time.
What should be the actual behavior of B now ... Should it go-ahead and
terminate the call immediately by responding to CANCEL or should it wait for
PRACK and then terminate the call ??
Here is the call flow observed in my lab.
A B
INVITE
----------------------------------->
180 Ringing(reliable)
<------------------------------------
CANCEL
-------------------------------------->
200OK
<----------------------------------------
PRACK
------------------------------------------>
200OK
<------------------------------------------
487
?---------------------------------------
ACK
---------------------------------------?
Please clarify me the behaviour of B in this scenario.
Regards,
Murali.
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Message: 2
Date: Fri, 4 Jun 2010 06:31:48 +0530
From: AMIT ANAND <amiit.anand at gmail.com>
Subject: Re: [SIPForum-discussion] CANCEL with reliable response ...
To: Sumeetkumar Bhardwaj <sumeet_bhardwaj at persistent.co.in>
Cc: "discussion at sipforum.org" <discussion at sipforum.org>
Message-ID:
<AANLkTimy5gV8RCYvSNyG87Yzc2IyeyybELy6kgNSxWXU at mail.gmail.com>
Content-Type: text/plain; charset="windows-1252"
Hi,
For B it is fine to respond with 200OK for PRACK , as it seems to be a race
condition between PRACK and 487. But this Behavior of A is wrong it should
not send PRACK after sending CANCEL. It does not make any sense to send
PRACK after sending a request to cancel.
Although RFC does not mandates it but it says that UAC should wait for
provisional response to send Cancel. So ideally A should have sent PRACK
first then should Initiate CANCEL.
Cheers
Amit
On Thu, Jun 3, 2010 at 10:55 AM, Sumeetkumar Bhardwaj <
sumeet_bhardwaj at persistent.co.in> wrote:
> Hello Murali,
>
>
>
> I think, If it gets the PRACK before terminating the call, it should
> respond to the 200 OK for that PRACK, but if it gets the PRACK after
> terminating the call, it should respond with the error ?481 call leg
> /transaction does not exists?. So, it just a matter of arrival of PRACK
> before and after terminating the call. So, I think, PRACK means
provisional
> response reliability, and if B got request to CANCEL the call, it has to
> CANCEL that INVITE transaction irrespective of reliability.
>
>
>
>
>
> Thanks,
>
> Sumeet
>
> * *
>
>
>
> *From:* discussion-bounces at sipforum.org [mailto:
> discussion-bounces at sipforum.org] *On Behalf Of *Murali Vuppandla
> *Sent:* Wednesday, June 02, 2010 6:33 PM
> *To:* discussion at sipforum.org
> *Subject:* [SIPForum-discussion] CANCEL with reliable response ...
>
>
>
> There are two SIP nodes A and B. A sends an INVITE with 100rel tag in
> Supported header. B sends 180 reliably with 100rel in Require header. A
> would like to CANCEL the call at this particular point of time.
>
>
>
> What should be the actual behavior of B now ? Should it go-ahead and
> terminate the call immediately by responding to CANCEL or should it wait
for
> PRACK and then terminate the call ??
>
>
>
> Here is the call flow observed in my lab.
>
>
>
> A B
>
> INVITE
>
> ----------------------------------->
>
> 180 Ringing(reliable)
>
> <------------------------------------
>
> CANCEL
>
> -------------------------------------->
>
> 200OK
>
> <----------------------------------------
>
> PRACK
>
> ------------------------------------------>
>
> 200OK
>
> <------------------------------------------
>
> 487
>
> ?---------------------------------------
>
> ACK
>
> ---------------------------------------?
>
>
>
> Please clarify me the behaviour of B in this scenario.
>
>
>
> Regards,
>
> Murali.
>
>
>
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--
Thanks
Amit Anand
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Message: 3
Date: Fri, 4 Jun 2010 01:02:38 +0530
From: Sam <u2nsam at gmail.com>
Subject: Re: [SIPForum-discussion] models Telephone wifi SIP
To: JMZ <jm_zacarias at yahoo.com.mx>
Cc: foro SIP <discussion at sipforum.org>
Message-ID:
<AANLkTinfnbs1j8BhwuXEMJY0nbGbXawuMKXdvBKzRQFF at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hello JMZ,
Use Nokia E - series Mobile phones , they are sip enabled and can make call
through WiFi.
Regards
Sam
On Thu, Jun 3, 2010 at 11:52 AM, JMZ <jm_zacarias at yahoo.com.mx> wrote:
> Hi to all.
>
> i tray to found telephone sip wifi, but In mexico its no common use these
> device, can you help to know what its the best option about
them....models,
> companys, contacts sales maybe...
>
> Regards..
>
>
>
> JMZ
> _______________________
>
>
>
> _______________________________________________
> This is the SIP Forum discussion mailing list
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Message: 4
Date: Fri, 4 Jun 2010 01:14:01 +0530
From: Sam <u2nsam at gmail.com>
Subject: Re: [SIPForum-discussion] When to bill a SIP Call ?
To: Ahmed Faisal Hassan <bappi22 at yahoo.com>
Cc: discussion at sipforum.org
Message-ID:
<AANLkTik05hpi6VdDnfvsVmCjZXAau-xXfzR0niQt5GAc at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hello,
Some start billing after 04 and some start billing after 05 depends on the
mechanism they are following.
Regards
Sam
On Thu, Jun 3, 2010 at 8:54 AM, Ahmed Faisal Hassan
<bappi22 at yahoo.com>wrote:
> Hi,
>
> Consider a very common scenario of a SIP call from A to B.
>
>
> A B
>
> 01 INVITE
>
> ----------------------------------->
>
> 02 100 TRYING
>
> <------------------------------------
>
> 03 180 Ringing
>
> <------------------------------------
> 04 200OK With SDP
>
> <----------------------------------------
>
> 05 ACK
>
> ------------------------------------------>
>
> 06 BYE
>
> <------------------------------------------
>
> 07 ACK
>
> ------------------------------------------->
>
>
> I need to know
>
> 1. where exactly 'A' party will start billing. After 04 or 05?
>
> 2. where exactly 'B party will start billing. After 04 or 05?
>
>
> Thanks
>
>
>
>
>
>
> _______________________________________________
> This is the SIP Forum discussion mailing list
> TO UNSUBSCRIBE, or edit your delivery options, please visit
> http://sipforum.org/mailman/listinfo/discussion
> Post to the list at discussion at sipforum.org
>
>
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