If you are attempting to track the WAN link and you are receiving an Ethernet hand-off from your provider, I would suggest tracking the ICMP reachability of an IP address within your service provider's network. Physical interface tracking will not help you in the case where there is an L2 failure beyond the handoff interface between you and your provider.
The first option would be to track the first hop router (I'm guessing 18.104.22.168 from your example?); a better solution would be to ask your ISP for the IP of one of their DNS servers or similar.
The way to do this is to create an IP SLA monitor operation, and create an object that tracks the state of the operation. The tracker object can then be used to decrement the HSRP priority of the LAN interface when the WAN interface goes down. This will vary depending on the code version you are running, but sample config below:
ip sla monitor 1
type echo protocol ipIcmpEcho 22.214.171.124
ip sla schedule 1 life forever start-time now
track 123 rtr 1 state
ip address 192.168.1.2 255.255.255.0
standby 1 ip 192.168.128.1
standby 1 priority 105
standby 1 preempt
standby 1 track 123 decrement 10
In summary, this:
- Creates an IP SLA operation that performs an ICMP echo targeted at 126.96.36.199, with a timeout of 10 milliseconds, with an interval of 5 seconds between probes.
- Schedules the IP SLA operation to run forever.
- Creates a tracking object which tracks the state of the IP SLA operation.
- Configures interface Fa0/1 with an HSRP address; configures HSRP to preempt; and configures HSRP to decrement its priority by 10 should the tracking object associated with the ICMP IP SLA monitor enter a down state.
This is very rough config based on referring to CCO; I will see if I can find something a little more polished in my notes.