thanks your answer.
the real situation is when time is up to noon , All CPU of four web proxies are up to 100%
I have two ftp proxies.
I hope when the web proxies cpus up to 85% the two ftp proxies can join the web proxy pool.
in normal time, the ftp proxy can focus ftp proxy function.
I reference the URL http://devcentral.f5.com/wiki/AdvDesignConfig.SNMPDynamicRatioMonitor.ashx
I try to change the action "set ratio" to "enable node".
But I found the command of URL is version 9.4.
I try to use tmsh in this sample, but it is fail.
Is the only solution icontrol in version 11?