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Transparent failover to an alternate broadband network
ACM500x-2 and IM/IMG42xx advanced console servers offer broadband failover. So in the event of a disruption to the main management network connection, access is switched transparently to the standby network connection.
With this service enabled:
- in the event of a failover - which is triggered by the failure of a ping to the nominated probe address - the console server switches to failover network connection
- the console server then is only accessible over this failover network connection. By default only SSH access is enabled on this failover connection. (However in firmware versions later than 3.0.1 HTTPS access and SSH accees to the serial ports are also enabled)
- the administrator can then SSH (or HTTPS) connect to the console server and fix the problem
You set up transparent failover when configuring the main Network 1 (eth0) connection in System: IP:
- Specify Network 2 (eth1) as the Failover Interface to be used when a fault has been detected with Network 1 (eth0).
- Then specify the Probe Addresses of two sites (the Primary and Secondary) that the console server is to ping to determine if Network 1 (eth0) is still operational
- Then on the Out-of-Band/Failover Interface tab uncheck Disable this network and configure Network 2 Settings (eth1) with the same IP setting that you used for Network 1 (eth0) to ensure transparent failover
In this mode, Network 2 (eth1) is available as the transparent back-up port to Network 1 (eth0) for accessing the management network. Network 2 (eth1) will automatically and transparently take over the work of Network 1 (eth0), in the event Network 1 (eth0) becomes unavailable for any reason.
By default the advanced console server does not support automatic failure-recovery back to the original state prior to the failover. So to restore networking to a recovered state the following command then needs to be run:
rm -f /var/run/*-failed-over && config -r ipconfig
If required, you can run a custom bash script when the device fails over. It is possible to use this script to implement automatic failure recovery, depending on your network setup. The script to create is:
/etc/config/scripts/interface-failover-alert
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