I have a UDP poller set that tells me how many APs are connected to a Cisco 5500 WLC. The number hovers around 183. I'd like an informational alert for when an AP leaves this WLC and I'll set an similar alert on my secondary WLC to see if the AP just disappeared or moved to the secondary.
It's a piece of cake to set an alert on a returned value not equal to 183, but I'd like to not have to change 183 to whatever the current number is, rather alerting on a delta from the previous poll.
The expected result is that I would get a delta alert on 2 WLC platforms if an AP moves; a tick upward on one, downward on the other.
Has anyone done anything like this?