I didn't understand how icmp poll from my NMS platform would help here. From the ASA, I have following configuration.
route outside 184.108.40.206 255.255.255.255 x.x.x.x
sla monitor 1
type echo protocol ipIcmpEcho 220.127.116.11 interface comcast
sla monitor schedule 1 life forever start-time now
track 1 rtr 1 reachability
route comcast 0.0.0.0 0.0.0.0 x.x.x.x track 1
route rcn 0.0.0.0 0.0.0.0 y.y.y.y 50
As you can see I am forcing my pings to 18.104.22.168 through Comcast interface. So when Comcast is down, I that ping will fail and I will move to secondary default.
If I ping 22.214.171.124 from the network management station, it will never go down. When Comcast is down, it will go through RCN interface but in either case, I don't know if I am on failover.
Now you may say that why am I pinging 126.96.36.199 not the default GW of the firewall. I had tried that too in past. Comcast has their router at the site and their LAN interface is my default GW. So that would really never fail even though their is upstream connectivity loss. That's why I have to ping something on the internet not the default GW.
NOTE: One would say to monitor syslog for message like "%ASA-6-622001: Removing tracked route... " would work. However that perticular syslog message is informational level. At that level of logging the ASA produces a ton of syslog volume which is what I am trying to avoid.