On 30 Mar 2015, at 16:54, Mark Michelson <[email protected]> wrote:

> On 03/28/2015 08:06 PM, Joshua Colp wrote:
>> George Joseph wrote:
>>>> The fact that it goes to unavailable would be a bug. Why does it do so?
>>> 
>>> Mark should probably chime in here but I think it's because the
>>> earliest you could get a response from pjsip when a contact isn't
>>> reachable is the unconfigurable 32 seconds.   As I said that's a long
>>> time to leave a contact available when it really isn't. Without
>>> implementing our own timer setting the contact to unavailable was
>>> probably the lesser of 2 evils.
>> 
>> No matter what there's going to be a period where you are potentially wrong. 
>> I don't think making it unavailable was done on purpose.
>> 
> Actually, I believe the timer may be configurable. In the type=system 
> settings, there are timer_t1 and timer_b settings. timer_t1 is the base used 
> for determining the retransmission interval, and timer_b is the maximum time 
> we will wait before giving up sending the request. The defaults for these 
> values are 500 ms and 32000 ms respectively. If you were to change timer_b to 
> be a smaller value, then presumably you would have a shorter time before the 
> transaction times out.
> 
> A couple of caveats about these settings
> 1) Since they're in the "type=system" settings, any change you make requires 
> an Asterisk restart in order to take effect.
Are you serious? That's a very strange design. Without knowing anything about 
PJSIP, I think that is something that
needs to be fixed. There are several SIP phones based on PJSIP where I can set 
timers without restarting. Wonder
how they did it. 

> 2) PJSIP applies these timers globally. They will affect ALL SIP 
> transactions, not just the OPTIONS transactions from the qualify checks.
That seems very strange, but I have to trust you here. It makes the channel 
driver rather unusable in gateway situations where
it's a requirement that I have one set of timers for my internal systems and 
one for external clients.

/O
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