Subject: Re: [Sip] Matching responses to transactions (error in 9th draft?)

From: [email-masked]
Date: Thu, 25 Apr 2002 11:25:42 -0400

>
>> Hi,
>>
> >Determining whether a response is a
> >>retransmission is actually hard, and not needed.
>>
>> Is this true that a UAC doesn't need to determine whether a response is
>> a
>> retransmission or not?
>> If so, wouldn't the UAC repeat the same processing for duplicate
>> responses
>> which would impact performance, especially when the response includes
>> SDP?

>No, there wouldn't need to be a repeat of the same processing. The state
>machine for the client transaction tells you whether you need additional
>processing. If a response matches the transaction, and the transaction
>is in the completed state, you resend the ACK - thats it. The state
>machine does not tell you to pass the response up to the TU, so no
>further processing occurs.
>
>-Jonathan R.

In case of 1xx received, the INVITE client transaction in the Proceeding
state tells you to pass the response up to the TU. In this case, is the TU
responsible for determining the duplicate response or for repeating the
same processing treating the duplicate response as a new response?

Thanks,
YoungSun

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 25 Apr 2002 13:48:07 -0400

> same processing treating the duplicate response as a new response?

For a bis compliant element, there is no differing treatment of
duplicate provisional responses. All are forwarded upstream by proxies,
all are associated with a dialog and possibly rendered to the user at a
UA. The reliability of provional responses spec defines reliability for
1xx, which has a notion of retransmits. It provides a separate header
used to determine retransmits. That processing is not done at the
transaction layer, but in the TU.

-Jonathan R.

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