[OpenSER-Users] TM-module and ACK to 2xx (doesnt terminate txn?)

Bogdan-Andrei Iancu bogdan at voice-system.ro
Wed Feb 13 11:38:14 CET 2008


Hi guys,

Just to bring some clarifications on the TM module.

once a transaction is completed (negative or 2xx reply), it is put on 
wait (wait timer - see RFC3261) for catching any potential 
retransmissions of replies.
So, the transaction is completed, but not removed from memory - RFC does 
not say that you need to trash immediately all the transaction 
information, but even describe the wait timer. So, there is no 
contradiction.

The ACK (for 2xx)catching is done based on the completed INVITE 
transaction (from wait timer) - nothing else.

The end-to-end ACK establish a separate transaction (RFC 3261) and these 
ACKs are not match as part of the INVITE transactions, but correlated 
with them.

Inaki, could you please detail what you mean by:

<quote>
In my opinion OpenSer does a special treatment for ACK in tm mode, even if 
they are for failed transaction (hop-by-hop ACK's) or succesfull INVITE 
(end-to-end ACK's).

</quote>

Maybe I can explain you more if I understand you question....

Regards,
Bogdan


Iñaki Baz Castillo wrote:
> On Tuesday 12 February 2008 12:18:15 Taisto Qvist wrote:
>   
>> t_check_trans() :
>>
>>  ACK request - true if the ACK is a local end-to-end ACK for an existent
>> INVITE transaction.
>>
>>     
>
>   
>>  To me, that sounds like a contradiction in terms, since there is
>> (rfc-wise) no transaction left after 2xx has been proxied through
>>     
>
> Good point. Hope there is a explanation of this behaviour.
> In my opinion OpenSer does a special treatment for ACK in tm mode, even if 
> they are for failed transaction (hop-by-hop ACK's) or succesfull INVITE 
> (end-to-end ACK's).
>
>
>   
>> Then how long does the transaction live after 2xx has been forwarded? 
>> How come its implemented this way?
>>     
>
> There is a specific timer in RFC 3261 for this purpose (if I'm not wrong). 
> Maybe OpenSer uses that timer to keep transaction info and during that time 
> matches the end-to-end ACK as part of the transaction (no very RFC of course, 
> but it seems to work).
>
>
> Regards.
>
>
>   





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