[Users] Best practice for DNS failover using OpenSER?
bogdan at voice-system.ro
Tue Jan 16 16:46:33 CET 2007
Klaus Darilion wrote:
>> Retransmissions are good (most of the time). Somehow the ser
>> script would need to know that there is another thread tending to
>> a DNS lookup. How does my script know if a message is original,
>> or a retransmission anyway?
>> It seems to me that the tm module should be reaping the retransmits.
> At first the proxy should reply 100 trying to stop retransmissions.
this is very and elegant to do with the new flags in t_reply(). You can
statelessly send a 100 and configure t_relay() not to do it again. See:
letting t_relay() to auto generate the 100 is in most of the case
futile, as it is too late.
> Further, the retransmissions should be absorbed by tm - if not then we
> should analyze it.
the TM functions do that, but again, in most of the case it, as the
relaying is done at the end of processing, it can be a wast of
computation and time - just to apply all changes and perform ops to
figure out at the end that the request was a retransmission.
So, you can use the t_check_trans() function from the beginning:
the great part is that the function does not affect the further
processing and has no computation penalties.
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