If you'd prefer to have it the way you requested then:

Code:
on *:CONNECT:{
  if ($network == [color:red]Network1[/color] || [color:red]Network1[/color] isin $server) {
    Commands to execute for Network1
  }
  else if ($network == [color:red]Network2[/color] || [color:red]Network2[/color] isin $server) {
    Commands to execute for Network2
  }
  else if ($network == [color:red]Network3[/color] || [color:red]Network3[/color] isin $server) {
    Commands to execute for Network3
  }
}



Where "Network isin $server" is specified it can also be NetworkX == $server
It's whichever one you prefer.