As Patrick alluded to, it can't fail over if it doesn't know you are down. It sounds like your DSL was in fact, up and even some routes were working, just others not were not. What device is handling the failover? It sounds like the billion is just the 4G device. I would look into the details of what mechanisms the router/load balancer uses to determine when to failover. Cisco ios can use IPSLA and PBR to do this, for example.
↧