Help required to construct Irule for Source based Http redirection

There a few issues with the iRule you've provided, I've re-written it to fulfill what I understand to be your requirements. To use this iRule there are three pools, siteA_pool containing site A members, siteB_pool containing site B members, and siteAB_pool containing members from both previous pools.

The iRule is quite basic and could be replaced with an LTM traffic policy.

when HTTP_REQUEST { 
    if {[IP::addr [IP::client_addr] equals 192.168.53.0/24]} {
        pool siteA_pool
    } elseif {([IP::addr [IP::client_addr] equals 192.168.1.0/21) || ([IP::addr [IP::client_addr] equals 192.168.16.0/21)} {
        pool siteB_pool
    } else {
        pool siteAB_pool
    }
}