[OpenSIPS-Users] Reducing INVITE delay until UAC sees 180 RINGING

[opensipslist at encambio.com]

Hello Bogdan,

An mar., déc 22, 2009, Bogdan-Andrei Iancu schrieb:
>opensipslist at encambio.com wrote:
>> An ven., déc 18, 2009, opensipslist at encambio.com schrieb:
>>> I'm assuming that a delay of 1 second is reachable through config
>>> tuning, and wondering as well what kind of result (in terms of delay
>>> time) the maximum tuning yields. Already I've looked at things like:
>>>
>>>  disable_dns_blacklist
>>>  disable_dns_failover
>>>
>>> ...because DNS resolutions is a logical place to start reducing.
>>>
>>> Any ideas? Is there documentation about this?
>>>
>> The OpenSIPS documentation is excellent of course, but sadly lacking
>> information about such core parameters as those above and 'rev_dns'
>> relating to when and how often they effect performance. For example,
>> does 'rev_dns = yes' mean that a reverse lookup takes place once at
>> startup, every time the route script is entered, once a new
>> transaction begins, dialog...
>>
>rev_dns affects two scenarios:
>- comparisons with domains in script ( like src_ip=="foo.bar") -
>reverse DNS will be done on foo.bar
>- internal checks of IPs against SIP uri / SIP hosts (like checking
>for VIA matching, for src IP nat, etc)
>
>Shortly, if when doing IP versus IP/domain checks, if reverse DNS
>should be done if "domain"
>
That seems rather expensive, resolving all but what is necessary as
the script is running for each incoming message. I guess that's why
it is disactivated by default.

I'll keep trying to find the sticking points leading to several
seconds of delay before 180 ringing. The alias table is db_text,
so maybe that is what is so slow. No enum is looked up.

Regards,
Brian