[sr-dev] fr_timer

[Andrei Pelinescu-Onciul]

On Oct 05, 2009 at 14:40, Klaus Darilion <klaus.mailinglists at pernau.at> wrote:
> Hi!
> 
> I just read the the documentation of the fr_timer nad I think it is 
> wrong (as K's documentation is identical and wrong).
> http://sip-router.org/docbook/sip-router/branch/master/modules/tm/tm.html#fr_timer
> 
> AFAIK, fr_timer is triggered if there is no "provisional" response 
> received, and not as the documentation said, a "final" response.

What you say it's valid only for the INVITEs.

> 
> Eg. I always used
> fr_timer: 2 seconds
> fr_inv_timer: 120 seconds
> 
> Which means that the callee has to send a prov. response (e.g. 100 
> trying) within 2 seconds, to achieve fast failover.

I think here you mean: to avoid fast failover.

> Once the prov. 
> response is received, fr_timer is deactivated and fr_inv_timer is used.
> 
> 1. Question: Is this the same in sr's tm module? If yes, then the docs 
> should be fixed (I can do that).

Yes, it's true.
However note that the docs are not wrong, only incomplete.
For anything besides an INVITE they are correct (e.g. REGISTER).

For an INVITE fr_timer is used until a provisional reply is received and
then  the timer "switches" to fr_inv_timer.

> 
> 2. If yes, what about renaming the parameters and introduce parameters 
> which are clear, e.g.:
> timeout_prov_reply and timeout_final_reply

We would still have a problem, since fr_timer is uses for different
purposes (non-INV final reply, INV negative reply retr. if no ACK arrives,
 INV intial timeout, until the first reply is received).

If needed in a future version we could switch to fr_timer (non-INV and
neg ACK wait), fr_inv_timer1 (wait for first INVITE reply),
fr_inv_timer2 (after provisional reply).

Andrei