I have single 5508 running v.9.5.
No router in front of the ASA.
Failover is set up as shown in the configuration below.
I have two questions, first, when primary ISP (Outside-TW) goes down and backup ISP (outside) becomes active, will it switch back automatically to primary ISP once it becomes available? Or am I missing some pieces in the config?
And second, what if the problem with primary ISP is further down the path than the gateway, how do I monitor both, the default gateway and for example 126.96.36.199?
ip address 188.8.131.52 255.255.255.252
ip address 184.108.40.206 255.255.255.248
route outside 0.0.0.0 0.0.0.0 220.127.116.11 11 track 1
route Outside-TW 0.0.0.0 0.0.0.0 18.104.22.168 1 track 2
sla monitor 1
type echo protocol ipIcmpEcho 22.214.171.124 interface outside
sla monitor schedule 1 life forever start-time now
sla monitor 2
type echo protocol ipIcmpEcho 126.96.36.199 interface Outside-TW
sla monitor schedule 2 life forever start-time now
track 1 rtr 1 reachability
track 2 rtr 2 reachability
To answer your questions:
1) Yes, the traffic should fail back over to the the primary ISP as the initial default route should show up back on the routing table. You config has a potential problem - both primary and backup default routes have the same metric (1). You should ideally have the backup route with a higher metric so that it takes effect only when the primary route is not longer present. You also do not need a track on your backup route as the route should always be up as backup. You can use the following guide as example:
2) Keeping the tracking as 188.8.131.52 has an advantage of being to track both gateway and other devices in the path. But if you keep only gateway you cannot check anything beyond. Again, this is a call you have to take on what you want to track. My recommendation would be to track 184.108.40.206. In any case, test and make sure that the tracking does not keep going down with that config.
this is the Right configuration you need
sla monitor 9
type echo protocol ipIcmpEcho 220.127.116.11 interface Primary_ISP
sla monitor schedule 9 life forever start-time now
track 9 rtr 9 reachability
route Primary_ISP 0.0.0.0 0.0.0.0 18.104.22.168 track 9
route Backup_ISP 0.0.0.0 0.0.0.0 22.214.171.124 10
the number "10" on the second routes is the AD which has to be higher than the primary but if you want autofailover you should never you the AD as 255 on the secondary route