[SIPForum-discussion] Choosing the best response. Clarification needed

Yevgen Krapiva ykrapiva at gmail.com
Wed May 13 12:22:01 UTC 2009


>then proxy sends final response when all transaction end.

It will happen when Timer D fires.

>so an absolute minimum of 32s is used instead of basing Timer D on T1.

Am I (UAC) supposed to wait 32 seconds before I get an answer from
proxy that my request failed ? It's too long. O_o
I'm saying that proxy must not wait when client transaction finally go
to terminated state. I think that COMPLETED state already gives me a
right to send the final response to UAC. Why not ?

2009/5/13, Tomasz Zieleniewski <tzieleniewski at gmail.com>:
> Hi,
> I think You have mistaken the completed with terminated state.
> When proxy receives 300-699 response this causes a proxy client transaction
> to
> transition to completed state. In which for unreliable transport it starts
> D
> timer
> in order to generate ACK for transaction response retransmissions.
> When D timer fires transaction transitions to completed state. (proxy
> removes any associated resources)
> Keep in mind that this a per transaction behavior. When there is forking at
> the proxy
> if the response is not 6xx or 200 then proxy sends final response when all
> transaction end.
> Kind regards,
> - Tomasz Zieleniewski
> 2009/5/12 Yevgen Krapiva <ykrapiva at gmail.com>
>> Hi.
>> Here is a quote from RFC 3261 Response processing section in statefull
>> proxies:
>> >6.  Choosing the best response
>> >
>> >         A stateful proxy MUST send a final response to a response
>> >         context's server transaction if no final responses have been
>> >         immediately forwarded by the above rules and all client
>> >         transactions in this response context have been terminated.
>> Should I treat the words "terminated transaction" as transaction in
>> TERMINATED state ? If yes, then keeping in mind that client
>> transactions created by proxy "live" for about 30 seconds in case of
>> 3XX-699 responses, then the UAC have to wait half a minute until the
>> proxy answers him.
>> In other words: If client transaction created by proxy receives
>> 3XX-699 response, then it will elapse 30 seconds before transaction
>> goes from COMPLETED to TERMINATED state. All this time proxy have to
>> wait until it sends the final response to UAC.
>> Is it normal ? Or should proxy choose the best response when all
>> client transactions goes to COMPLETED OR TERMINATED state ?
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