Subject: Re: [Sip] Why do we need 3-way handshake for INVITE transaction....

From: "Vishal Phirke" <[email-masked]>
Date: Fri, 30 May 2003 16:07:28 -0400

Well...As per my understanding, the dialogs will be established as soon as
UA receives 200 OK. The application will generally accept first 200 OK,
sending ACK and will reject others by sending BYE. What I was trying to get
to is sending an ACK will make sure that both parties know that the other
party is ready for session. However, for other requests, which are within
dialog, the end points already know that the other end point is ready to
accept its requests.
-Vishal

                      "Nataraju A.B."                                                                      
                      <natarajuab@huawe        To:       Vishal Phirke <[email-masked]>            
                      i.com>                   cc:       [email-masked], [email-masked]                  
                      Sent by:                 Subject:  Re: [Sip] Why do we need 3-way handshake for      
                      [email-masked]         INVITE transaction....                                     
                      g                                                                                    

                      05/30/2003 03:15                                                                     
                      PM                                                                                   

vishal,

does ur 2nd point mean that the SIP application  might select one of the
'n'
replies to the INVITE request (if it was not intenede for multi-party
call).
even in this case it is logical to derive that application will selecet the
first response and reject the later 2xx responses OR will the application
wait for some time before sending the ACK back to callee.

Regards,
-Nataraju A.B.
----- Original Message -----
From: "Vishal Phirke" <[email-masked]>
To: "Nataraju A.B." <[email-masked]>
Cc: <[email-masked]>; <[email-masked]>
Sent: Saturday, May 31, 2003 12:33 AM
Subject: Re: [Sip] Why do we need 3-way handshake for INVITE
transaction....

>
> Apart from offer-answer mechanism, INVITE transactions differ from other
> transactions in following ways:
> 1. They take more time and often an user intervention is required.
> 2. Invites can be forked. And if multiple destinations send 200 OK, you
> don't want to end up with multiple connections. Instead, 3-way handshake
> allows the decision of accepting one of them delayed till Ack is sent by
> the originator of the request.
> Hence, it is very important to do reliable handshake at the time of
session
> establishment.
> -Vishal
>
>
>
>                       "Nataraju A.B."
>                       <natarajuab@huawe        To:       [email-masked]
>                       i.com>                   cc:
>                       Sent by:                 Subject:  [Sip] Why do we
need 3-way handshake for INVITE
>                       [email-masked]         transaction....
>                       g
>
>
>                       05/30/2003 02:04
>                       PM
>
>
>
>
>
>
> Hello All,
>
> I have a doubt why do we really need 3-way handshaking for INVITE
> transacation.
> whereas most of the others employ 2-way handshaking (BYE/200,
> UPDATE/200...).
>
> According to my knowledge one of the reason could be offer-answer
mechanism
> involved in INVITE transactions.
>
> Thanx in advance,
>
> Regards,
> -Nataraju A.B.
>  Huawei Technologies Ind Pvt Ltd,
>  Bangalore-560008,
>  +98455.95744
>
> _______________________________________________
> Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
> This list is for NEW development of the core SIP Protocol
> Use [email-masked] for questions on current sip
> Use [email-masked] for new developments on the application of sip
>
>
>
>
>

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
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_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip