[OpenSIPS-Users] TCP AORs and db_mode 1/2/3

[opensipslist at encambio.com]

Hello Bogdan,

An lun., févr 08, 2010, Bogdan-Andrei Iancu schrieb:
>opensipslist at encambio.com wrote:
>> Thinking today about why my messages are sometimes routed to
>> nonexistent TCP endpoints, I came upon the following idea:
>>
>>   It seems that if the usrloc db_mode is anything but 0,
>>   then TCP AORs could be read from the database after a
>>   crash. This can't work because once OpenSIPS stops,
>>   the TCP connections are destroyed. They aren't reusable
>>   again, because routers and firewalls would block the
>>   connections that OpenSIPS tries to reestablish.
>>
>> First of all, is that right?
>>
>That is correct.
>
>> If so, then for what reason are the db_modes 1, 2, and 3
>> even useful at all? For UDP-only systems, right?
>>
>not really. Even if the TCP conn is lost while the registration
>still valid, the conn can be re-established from the client side
>(like the client placing a call).
>
I tested this and at least with my routers when a TCP connection
to OpenSIPS is lost the NAT binding is destroyed. Should the UAC
place a call once OpenSIPS is started again, a new TCP connection
is created with a new NAT binding and a different outgoing TCP port.

That means that should OpenSIPS reuse the old TCP port from the
registration in usrloc, then it could send for example a NOTIFY
to the wrong place, right?

By the way, I set db_mode to 0 to avoid this problem. The location
table in db_text is still being populated when save() is called.
Doesn't the db_mode '0' parameter of usrloc mean that nothing will
be written to the database when save() is called?

Regards,
Brian