[asterisk-users] Need to restart Asterisk if remote server not working?

Max Grobecker max.grobecker at ml.grobecker.info
Sat May 6 08:35:59 CDT 2017


I'm also a customer of the DTAG.
Yesterday, the messed a bit with their DNS entries...

If you are NOT using their DNS resolvers you got a "wrong" IP address back that was not working.
Besides that, you should disable SRV lookups for their SIP peers. Since Asterisk's chan_sip.c does not honour the
weight of the SRV entries, nor it failovers to the other records, you might just end up with a not working server.
PJSIP might work with that, but it depends on your version.

The "blank" A record for "tel.t-online.de" is also provided and will be changed in case of service disruptions on one server,
so it's acceptable to rely on that.

DTAG is providing the following SIP servers at the moment (and also yesterday) with their SRV records:

_sip._udp.tel.t-online.de. 401  IN      SRV     0 5 5060 ims001.voip.t-ipnet.de.
_sip._udp.tel.t-online.de. 401  IN      SRV     1 5 5060 ims002.voip.t-ipnet.de.

ims001 should be the preferred one based on the SRV weight. But Asterisk only looks at the first record that comes as an answer,
so if ims002 is at the first position it will be used for registration, regardless that the other record is weighted better.
And if that one is not answering...
So: Better disable SRV lookups if you are not sure if your SIP channel driver supports it ;-)

You should also use the dnsmgr of Asterisk, resp. configuring it to reasonable values.
In dnsmgr.conf I set:

enable = yes
refreshinterval = 10

If dnsmgr is not enabled on your server this might have caused the problem because your SIP driver did not recognized that the
target address of the configured hosts has changed.
DNS changes should work also without dnsmgr - but since I've enabled the dnsmgr I had far less problems with changing DNS records ;-)

Am 06.05.2017 um 09:37 schrieb Luca Bertoncello:
> Hi list!
> Yesterday Deutsche Telekom had a really big problem and Asterisk couldn't
> connect to the remote Server (by Telekom) until today about 7:30.
> Well, it could happen...
> What I find really annoying was that I needed to restart Asterisk as I
> checked with sipsak that the Telekom-Server works...
> I think, this should not be normal... Can someone explain me why it happens
> and what I have to change in the configuration to avoid this problem?
> Thanks a lot
> Luca Bertoncello
> (lucabert at lucabert.de)

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