This is an interesting answer and there are obvious use cases for EEM in this fashion so thank you for the input.
Howver, I think it would be a tad complex to achieve dynamic link management without operator intervention at some point using EEM in the same way flex links operated though. It could definitely operate as an last resort backup but the admin would need to then go and manually swap the system back to the normal interfaces after investigation.
Effectively one needs to achieve a link swap in the event of loss of throughput no matter which of the pair is currently active.
We cannot rely solely on link down as a port misconfig could prevent config even if the link is up, so the IP SLA example gives us a good option here.
But effectively what we would need to achieve is. Whichever interface is currently active, if we lose ICMP then shut that interface and open the other.
Achieving this with EEM seems like it would be a challenge, we also would not be able to achieve preemptive fallback in any way I can immediately think of, because we are shutting the "failed" interface we then cannot monitor to establish if connectivity is recovered.
Flex links seems as if it offered a solution to all of these issues.
