my $backup_host  = "tftpserver.somewhere.net";
  my $device       = "cisco.somewhere.net";
  my $type         = "router"; # or "switch";
  my $ios_version  = 12;

  my @out;
  if ($type eq "router") {
      if ($ios_version >= 12) {
          @out = $session->cmd("copy system:/running-config "
                        . "tftp://$backup_host/$device-confg\n\n\n");
      } elsif ($ios_version >= 11) {
          @out = $session->cmd("copy running-config tftp\n$backup_host\n"
                        . "$device-confg\n");
      } elsif ($ios_version >= 10) {
          @out = $session->cmd("write net\n$backup_host\n$device-confg\n\n");
      }
  } elsif ($type eq "switch") {
      @out = $session->cmd("copy system:/running-config "
                    . "tftp://$backup_host/$device-confg\n\n\n");
  }