Never mind when you start adding fault-tolerance and failover setups/configs to the mix.
It gets really complex really fast, and even the slightest lapse in attention to extreme detail can be disastrous and a nightmare to troubleshoot.
For instance, I once had a router reboot for some unknown reason, and the firmware/config wasn't properly flashed, so it reverted to the last point release of the firmware. That was enough to cause the failover heartbeat to be constantly triggered, and the master/slave routers just kept failing over to each other and corrupted all the ARP caches. Makes for a lot of fun when things work and then stop working in an inconsistent manner.
It gets really complex really fast, and even the slightest lapse in attention to extreme detail can be disastrous and a nightmare to troubleshoot.
For instance, I once had a router reboot for some unknown reason, and the firmware/config wasn't properly flashed, so it reverted to the last point release of the firmware. That was enough to cause the failover heartbeat to be constantly triggered, and the master/slave routers just kept failing over to each other and corrupted all the ARP caches. Makes for a lot of fun when things work and then stop working in an inconsistent manner.