redirect based on Source IP

first, create a datagroup with the rfc1918 space

ltm data-group internal rfc1918 {
    records {
        10.0.0.0/8 { }
        172.16.0.0/12 { }
        192.168.0.0/16 { }
    }
    type ip
}

then you can use this iRule

when HTTP_REQUEST {
  if { ! [class match [IP::client_addr] equals "rfc1918" ] } {
    HTTP::redirect "https://[HTTP::host][HTTP::uri]"
  }
}