I wonder if anyone used iCall to trigger external call to another device - I guess that is right tool for the job, or maybe there is some better solution.
I think I would use a sideband connection in an iRule for this, I think it would be easy enough. The iRule can trigger on a violation event and send a request of your own design to the device.
Thanks for pointing to sideband. I wonder what is more performance friendly assuming thousands (20k+) TCP connections per second?
Hard to say, but I would guess sideband connections since iRules are handled by the TMM:s. I don't know exactly how iCall is implemented but since it's part of the management side of the BIG-IP and all management processes run outside of the TMM:s and thus have limited resources compared to TMM.