lb::select question

Robbie, what do you mean "it should know which pool the traffic is sent"?

if you want to make sure a pool exists before using it, use 'catch', like this irule:

when HTTP_REQUEST {
   set POOL [substr [string tolower [HTTP::host]] 0 ":"]
   if { [catch { pool $POOL } ] } {
     set POOL default_pool
   }
  pool $POOL
}

This irule attempts to use a pool that matches the Host header sent by the browser, and if it does not exist sends traffic to default_pool.