Hi,
As per the scenario you have single interface connected to a broadcast network of /24. You dont have to do anything the links shows an example how to do it you may tweak the configuration to achieve the goal..
E.g
You have 192.168.1.1 for ASA
192.168.1.100 primary router
192,168.1.200 secondary router
monitor the ISP facing interface on primary router using IP SLA so when the link to ISP is down, back up route is installed. further add a route on ASA for outside interface of primary router towards 192.168.1.100 so that monitor traffic always goes that way. add the following routes on ASA
route outside 0.0.0.0 0.0.0.0 192.168.1.100 1 track 1
!--- Enter this command in order to track a static route.
!--- This is the static route to be installed in the routing
!--- table while the tracked object is reachable. The value after
!--- the keyword "track" is a tracking ID you specify.
route outside 0.0.0.0 0.0.0.0 192.168.1.200 254
As long as you can ping the outside interface of primary router the first route will be used if the reachability is lost than that route will be withdrawn and secondary path towards 1.200 will be used.
sla monitor 123
type echo protocol ipIcmpEcho interface outside
num-packets 3
frequency 10
sla monitor schedule 123 life forever start-time now
track 1 rtr 123 reachability
So till the time sla monitor 123 has successful attempts, Track 1 is true, primary route is installed when sla 123 is unsuccessful, Track 1 is down and route is withdrawn and default route towards secondary is used with AD of 254
HTH
Hitesh Vinzoda
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