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

["Vishal Phirke" <vishal_phirke@nmss.com>]

I think the problem with the forking is, when an INVITE is forked and you
actually want to setup multiple calls.
In such a case application will send INVITE without SDP body and each 200
OK will carry an offer in SDP to which application can respond via using
ACK with separate media ports for each connection. If 3-way handshake is
not supported, setting up multiple calls with one INVITE is not possible.
-Vishal


                                                                                                           
                      "Arjun                                                                               
                      Roychowdhury"            To:       "Vishal Phirke" <vishal_phirke@nmss.com>          
                      <aroychow@hns.com        cc:       "Nataraju A.B." <natarajuab@huawei.com>,          
                      >                         sip@ietf.org, sip-admin@ietf.org                           
                      Sent by:                 Subject:  Re: [Sip] Why do we need 3-way handshake for      
                      sip-admin@ietf.or         INVITE transaction....                                     
                      g                                                                                    
                                                                                                           
                                                                                                           
                      05/30/2003 03:57                                                                     
                      PM                                                                                   
                                                                                                           
                                                                                                           




On 05/30/2003 03:03:53 PM, "Vishal Phirke" wrote:

> 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.
>

I dont think this is a valid reason for 3-way handshakes. By definition,
all 200 OKs are proxied back. Its upto the caller UA
to then send BYE/OK to callees that it does not want to talk to due to
forking. Therefore, the ACK is sent to all of them and doesnt
help in delaying the decision.

regds
arjun

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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 sip-implementors@cs.columbia.edu for questions on current sip
Use sipping@ietf.org for new developments on the application of sip