[SIPForum-discussion] transaction...

[alexzhang at gdnt.com.cn]

Hi,
 
Yes, ACK is created by the transaction user. But we should figure out
the background reason why a new transaction is needed to create an ACK
message for the 200OK(invite). 
 

Thanks, 
Alex  
6-554-8782 

 

________________________________

From: Surya Prakash Ummadi [mailto:suryaprakashu at rediffmail.com] 
Sent: Sunday, August 19, 2007 12:49 AM
To: Alex Zhang (GDNTRND)
Cc: discussion at sipforum.org; baolovebao at gmail.com;
devanand at techmahindra.com
Subject: Re: Re: [SIPForum-discussion] transaction...





Hi all,

  AcK is considered separate transaction as it is created by the
Transaction User , which it has to be informed to the User that the call
is established now and it is also useful for the billing information
also.

please comment ...


regards
surya
On Fri, 17 Aug 2007 alexzhang at gdnt.com.cn wrote :
>What you said is not the root cause. Please refer to the RFC3261 -17.
>Transactions:
>
>      The reason for this separation is rooted in the importance of
>      delivering all 200 (OK) responses to an INVITE to the UAC.  To
>      deliver them all to the UAC, the UAS alone takes responsibility
>      for retransmitting them (see Section 13.3.1.4), and the UAC alone
>      takes responsibility for acknowledging them with ACK (see Section
>      13.2.2.4).  Since this ACK is retransmitted only by the UAC, it
is
>      effectively considered its own transaction.
>
>And in my opinion, when the transaction layer of the UAC/UAS will be
>destroyed as soon as the 200 OK(Invite) is received. At this time, the
>UAC and UAS already know the location of each other. It means that the
>stateless proxy between them is not used any more. The ACK, which is
>created in a new transaction, will be transmitted from UAC to UAS
>directly.
>
>Thanks,
>Alex
>6-554-8782
>
>
>
>________________________________
>
> From: discussion-bounces at sipforum.org
>[mailto:discussion-bounces at sipforum.org] On Behalf Of Donald Lee
>Sent: Friday, August 17, 2007 3:05 PM
>To: Devanand Kumar
>Cc: discussion at sipforum.org
>Subject: Re: [SIPForum-discussion] transaction...
>
>
>because it has unique Via branch-ID, which identifying the transaction.
>
>
>On 8/17/07, Devanand Kumar <devanand at techmahindra.com> wrote:
>
>
>
>      Hi ALL,
>
>
>
>      Please tell me the reason that why The ACK for a 2xx response to
>an INVITE request is a separate transaction.
>
>
>
>      Thanks and Regards,
>
>      Devanand Kumar
>
>
>
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>BR
>Donald
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