print map  { substr($_, 13) }
      sort
      map  { my ($src, $dst) = (split)[0, 2];
             $src = pack('C4n', split(/[.:]/, $src));
             $dst = pack('C4n', split(/[.:]/, $dst));
             $src lt $dst ? "$src${dst}0$_"
                          : "$dst${src}1$_"           }
      <DATA>;

##</code><code>##

print map  { my @f = unpack('C4nC4na', $_);
             my $src = "$f[0].$f[1].$f[2].$f[3]:$f[4]";
             my $dst = "$f[5].$f[6].$f[7].$f[8]:$f[9]";
             ($src, $dst) = ($dst, $src) if $f[10];
             "$src -> $dst\n"                          }
      sort
      map  { my ($src, $dst) = (split)[0, 2];
             $src = pack('C4n', split(/[.:]/, $src));
             $dst = pack('C4n', split(/[.:]/, $dst));
             $src lt $dst ? "$src${dst}0"
                          : "$dst${src}1"             }
      <DATA>;

##</code><code>##

{
   open(local *TEMP, '>', $sort_input);

   while (<DATA>) {
      my ($src, $dst) = (split)[0, 2];
      $src = pack('C4n', split(/[.:]/, $src));
      $dst = pack('C4n', split(/[.:]/, $dst));
      my $data = $src lt $dst ? "$src${dst}0" : "$dst${src}1";
      print TEMP (unpack('H*', $data), "\n");
   }
}

...[ call external sort tool ]...

{
   open(local *TEMP, '<', $sort_output);

   while (<TEMP>) {
      chomp;
      my @f = unpack('C4nC4na', pack('H*', $_));
      my $src = "$f[0].$f[1].$f[2].$f[3]:$f[4]";
      my $dst = "$f[5].$f[6].$f[7].$f[8]:$f[9]";
      ($src, $dst) = ($dst, $src) if $f[10];
      print("$src -> $dst\n");
   }
}