Ich habe es zwar selber noch nicht probiert, aber seit Version 7.2 ist folgendes möglich:
Cisco Security Appliance Command Reference, Version 7.2 - queue-limit through router rip Commands [Cisco ASA 5500 Series Adaptive Security Appliances] - Cisco Systems
The following example uses an SLA operation to install a default route to the 10.1.1.1 gateway on the outside interface. The SLA operation monitors the availability of that gateway.If the SLA operation fails, then the backup route on the dmz interface is used.
hostname(config)# sla monitor 123
hostname(config-sla-monitor)# type echo protocol ipIcmpEcho 10.1.1.1 interface outside
hostname(config-sla-monitor-echo)# timeout 1000
hostname(config-sla-monitor-echo)# frequency 3
hostname(config)# sla monitor schedule 123 life forever start-time now
hostname(config)# track 1 rtr 123 reachability
hostname(config)# route outside 0.0.0.0 0.0.0.0 10.1.1.1 track 1
hostname(config)# route dmz 0.0.0.0 0.0.0.0 10.2.1.1 254
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