iRule to load balance based on source IP

Let's try that again with better formatting.

when CLIENT_ACCEPTED {
  ! Use getfield to pull the source IP address's third octet and determine if its
  ! even or odd.
  set third-octet [expr {[getfield [IP::client_addr] "." 3]}]
    if { [$third-octet ends_with 0,2,4,6,8]
      { set destination even }
    elseif
      { set destination odd }

  ! Send even sources to one Pool member, odds to the other.

  if { [$destination eq odd] 
    pool Application-pool member server1 80
    persist source_addr 14400
  }
  if { [$destination eq even]
    pool Application-pool member server2 80
    persist source_addr 14400
  }
}

  !If a pool member is not available, send the session back to the Pool and
  !set the persistence for a 60 minute timeout

when LB_FAILED {
  pool Application-pool
  persist source_addr 3600 LB::reselect 
}