“Simple” Failover Configuration

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Asterisk Users 6 Comments

At present I have two hardware identically freepbx/asterisk boxes. The mysql db on one is slaved to the other and all config files are rsync’d once every 24 hours (we have few configuration changes).

We use Polycom 321/331/550/650 phones, and I notice that these phones can be configured with two SIP servers.

Would the simplest approach to failover be to just configure my primary Asterisk server as the first SIP server and my backup as the second?

Kind Regards, Chris

6 thoughts on - “Simple” Failover Configuration

  • server has returned after an outage, you will likely end up with a partition, won’t you?

  • Polycom phones after firmware 2.x register to BOTH the primary and backup servers.

    Would the simplest approach to failover be to just configure my primary asterisk server as the first SIP server and my backup as the second?

  • You can actually configure at least some Polycom phones to 3 or more SIP
    servers. Your problem is going to be that when one of your servers is down for whatever reason, the “line key” attached to that server will be “off”. In a “Dual Server” environment, I would lean toward putting something like Kamailio (sp) in line so it can determine which server is the active one.

    —–Original Message—

  • What I have found most difficult in any failover situation is having everything decide at the same time something has failed.
    (this applies to anything not just asterisk)
    For example how does the polycom react if it can make the sip connection, but no outbound routes are available on the primary server for some reason ? Is your setup smart enough to actually shut down asterisk completely if its upstream network interface or route is dead to prevent local connections ?

    what if both servers are in that situation ? would they both shut down, neither ? what would you want to happen in that case ?

    They are not trivial questions to answer and the answers depend on your setup, there is no univeral right way of handling it.

  • ran into this before on routers, you can put something like that or vrrp or carp in front of a pair of systems to fail to the right one BUT there isn’t only one interface on something like a pbx, it has a lan interface and a wan interface, you have to get failover happening on the ALL at the same time which is tricky since when you fail one interface that sometimes eliminates being able to trigger the other interface to fail over since it no longer has any access to get a signal there.

    If you want to be able to look at the system to see why it failed you have to have some other way in as well.

    Every requirement just makes it more complex, and more fun to test.