Dynamic throttling based on target system CPU load

There's a few ways you could do this (an iRule with Sideband connections, an external monitor perhaps?) but the simplest would be to have the server/hosts make the decision on load and simply report whether it's acceptable or not. You could then use a monitor to probe the page for some specific text that's only present when the load is high and mark the pool member as down. As long as you are using the default Action on Service Down setting as None existing connections remain but no new ones are established to that host/service. When it's load reduces, the page text changes again and it's marked up. You can use the Pool Slow Ramp Time and health monitor Time Until Up settings to ensure the host isn't hammered when it returns to the Pool and that it's genuinely healthy again.

 

 

It might not read like it but this is infinitely better than using an iRule to control load balancing. If the hosts can't do the necessary an external monitor and related script that can is still preferable to the iRule.