Switch & external datagroup file

 Datagroups 
class ip_to_dg_name_dg {
   {
      host 10.10.10.10 { "classA" }
      host 10.11.10.10 { "classB" }
      network 10.12.0.0/16 { "classB" }
      network 10.13.0.0/16 { "classC" }
   }
}

class classA {
   {
      "classA_trx1" { "poolA" }
      "classA_trx2" { "poolB" }
   }
}

class classB {
   {
      "classB_trx1" { "poolC" }
      "classB_trx2" { "poolD" }
   }
}

class classC {
   {
      "classC_trx1" { "poolE" }
      "classC_trx2" { "poolF" }
   }
}

when CLIENT_DATA {
    set pay1 [TCP::payload 8]
    binary scan $pay1 IA4 len1 trx
     Check if $trx was matched
    if {$trx ne ""}{
         Look up the client IP in the ip to datagroup name datagroup
        set dg [class match -value [IP::client_addr] equals ip_to_dg_name_dg]
    
         Check if there was a match and the datagroup exists
        if {$dg ne "" and [class exists $dg]}{
             Look up $trx and get the corresponding pool
            set trx_value [class match -value $trx equals $dg]
             Check if there was a value returned from the class match
            if {$trx_value ne ""}{
                 Do something with the return value, like assign a pool
                if {[catch {pool $trx_value} result]==0}{
                     Assigned the $trx_value pool successfully, so stop processing the iRule
                    return
                } else {
                     Failed to assign the $trx_value pool
                }
            } else {
                 Lookup of $trx in $dg failed
            }
        } else {
             $dg was not matched or did not exist
        }
    } else {
         $trx was not found
    }
}

switch -glob [IP::client_addr] {
   1.1.1.1 {
       client IP was 1.1.1.1, do something
   }
   2.2.2.2 {
       client IP was 2.2.2.2, do something
   }
   2.2.3.* {
       client IP was 2.2.3.x, do something
   }
   2.3.*.* {
       client IP was 2.3.x.x, do something
   }
   default {
       client IP was not matched, do something by default
   }
}