The manual suggests this rule:
START
iRule my_iRule
when CLIENT_ACCEPTED {
if { [IP::remote_addr] eq matchclass aol } {
pool aol_pool
} else {
pool all_pool
} ...
There is a known issue (CR42434) in 9.0.2 where IP classes containing network addresses are not compared using the networks mask. This has been corrected in the forthcoming 9.0.3.