I have a Cisco 1801 on a remote site with dual WAN connections, with route maps to correctly NAT depending on which interface the traffic leaves via. I use IP SLA to adjust the default route from the primary interface (Dialer1) to the backup interface (Dialer0) when the primary interface goes down.
The problem I have is that I can't ping the backup interface when the primary is up, because the default route correctly directs all traffic back out of Dialer1. This is bad as it means I can't monitor the backup for failures, which means I could lose the primary only to find that the backup is also down.
I assume I need to do PBR to send traffic back out of the interface that it came from, but I can't work out how.
Do I need to do PBR on Dialer0? If so not sure what to set in order to get traffic going back out the same way. Am sure this is simple but can't seem to find the right resource to read.