We've implemented this feature on four of our ASA5510s that have multiple ISPs attached. It works fine, but I'd like some details on the inner workings of this feature. When I define the number of packets at 3, and the frequency at 20, What causes the route to be detected as failed? Does it have to detect three consecutive missed echos and fail on the fourth missed packet? If it loses three, then sees echos for the next, dows the route stay up? Is the packet count like a "down/up" counter, meaning that successes after failures reset the count availability to three? What is the time between echo packets sent? How dows the ASA begin using the tracked route after it becomes available again? What does the "rtr" portion of the command actually signify? I have dug deeply into Cisco and other on-line resources over the past several days, but have not found answers to these issues. If there are documents available that answer my issues, please provide links. Thank you!
To answer your question if 3 echoes fail then the ASA marks the route as failed and uses the other one. Now it keeps pinging though and if it sees a reply from the primary route it marks it as functional again and uses it.
The rtr part sssociates a tracked static route with the SLA monitoring process. The track ID corresponds to the track ID given to the static route to monitor: "rtr" = Response Time Reporter entry. 123 is the ID of the SLA process defined above.
I hope it answers your question.