3CX Failover with multiple ISPs (WAN IPs)

[Scot Busby]

Hello,

I have seen this thread posted before, however, I did not see any clear answer given the current version of 3CX, so my apologies if I missed anything.

We have 2 ISPs configured as failover on our router. The data works fine, our Windows-based, on-premise 3CX system is configured as a static External IP - our primary connection. When the primary connection fails, the backup kicks in, but I have to manually change the External IP address on the 3CX server before two-way audio is re-established. A while back, I had a failover server configured also, but this caused to many problems with bouncing back and forth, so I shut it down. I thought I'd pick it up again given it's been a major version or so ago since last tried.

If I remember correctly, the Dynamic Public IP setting is the setting I need to use - even though I have two static IP addresses (one for primary and one for backup), is that accurate? If not, what is the best practice for setting this up in a single-server environment?

Once I can get the single server working properly, I will re-introduce the backup server and try to get that to work so we have hardware redundancy.

Thank you for your help!

 

[Charles_3CX]

Although this is not recommended, as a static public IP is required, the only way this will work automatically when you have an ISP failover is to set the system to use a dynamic public IP, then configure NAT port forwarding for the required ports on both the ISP connections back to the 3CX System.

Although by the backup server, I'm guessing you mean using the 3CX Failover, you would need a way to configure your firewall to change the internal IP for the NAT port forwarded ports when failover occurs which you may need to do manually or, if supported, via scripts.

 

[Scot Busby]

@Charles_3CX,

Thank you for your reply. Back when I tried setting the system to Dynamic Public IP (more than a year ago) the system started acting erratically - dropping calls /cutting off calls in progress. I will take this one step at a time and switch to Dynamic Public IP and see what happens. If this is stable, I can look into the 3CX Failover next.

I spoke with my sip trunk provider to get the best practices from them as well, so we are working through some things here as well.

Thank you!