[OpenSIPS-Users] Loops between OpenSIPS when using DNS SRV

Stas Kobzar stas.kobzar at modulis.ca
Thu Dec 10 16:18:37 CET 2015

Hello List,

We have a several OpenSIPS running (1.11) and they have same priority in
Also OpenSIPS replicate REGISTER to share user location information.

Yesterday we had a loop caused by some buggy UAC (Polycom 501) when the
phone has sent CANCEL with URI containing domain name and which
(apparently) was not recognized by tm as a part of any dialog.

So the proxy01 has resolved domain name with another OpenSIPS (proxy02) and
relayed it to it. And proxy02 did the same and relayed it back to proxy01
and so on. This caused the loop which caused communication problems and we
had to restart all OpenSIPS routers to fix it.

My question is if anyone had this kind of problems and what is the best
practices to solve it.
We have in mind several ideas:
1 . Block any traffic from another OpenSIPS servers except REGISTER packets
(to allow locations replication)
2. Looped packets has dozens of Via headers, and we can check if there too
many via headers and drop packet. The max-forward header is decreasing but
problem happens before all 70 forwards passed.
3. Migrate to OpenSIPS 2, use binary replication and block SIP traffic
between OpenSIPS.
4. Add some delay before processing packets

Thank you in advance,


Stas Kobzar

Developeur VoIP / VoIP Developer

Modulis­.ca Inc.

# Bureau / Office: 514-284-2020 x 246

Email: s <http://firstname.lastname>tas.kobzar at modulis.ca


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