[SR-Users] Redundancy between 2 Kamailio servers

[Klaus Darilion]

Am 27.01.2011 11:21, schrieb Danny Dias:
> Hello my friends,
> 
> I wonder if someone has done this before? i would like to implement 2
> Kamailio servers with redundancy, something like the following:
> 
> SERVER_A is working as the primary sip proxy (virtual IP as the sip
> signaling), if it fails, the other server (sleeping) should UP the virtual
> IP and takes all the traffic....i guess there is many Linux implementations
> thah can do this, but i would like to know if there is someone that has done
> this before and hear some recomendations...
> 
> I've read some difficulty in the synchronisation of registrations because
> Kamailio works best when it stores registrations in memory and registrations
> are constantly changing - they expire and are renewed, as well as new ones
> joining and old ones leaving. To make the failover solution function
> seamlessly, it is necessary to synchronise the in-memory registrations
> between the primary and the backup server . This can be done by forking a
> copy of the registration request to the backup server, but there are some
> practical problems in doing this, has anyone do something with this?

Yes - the problem with SIP based replication is that both proxies must
be running. This is a problem as Kamailio binds to the virtual IP at
start up - thus adding the virtual IP address to the backup server does
not make Backup-Kamailio listening to the new IP address - you would
have to restart the backup Kamailio.

I think most people either have a database (which is highly-available by
itself) which is used by both proxies, or every proxy has a local
database and the synchronization is on DB level (e.g. master-slave
replication, btw: does somebody know if usrloc DB queries are suitable
for master-master replication?)

regards
klaus