Sometimes its worth it to just turn off uninitialized warnings:

use strict;
use warnings;

my @hash=(
{
     1 => "Gi1/0/1",
     2 => "Gi1/0/0",
     3 => "Gi1/1/1",
     4 => "Gi2/0/0",
     5 => "Gi2/0/1",
},
{
         1 => "1",
         2 => "2",
         3 => "3",
         4 => "4",
         5 => "5",
},
{
         1 => "2/1",
         2 => "4/5",
         3 => "15/1",
         4 => "1/1",
         5 => "1/2",
},
{
         1 => "Fa0/1",
         2 => "Fa0/2",
         3 => "Fa3/1",
         4 => "Gi0/1",
         5 => "Gi0/0",
});
[download]

foreach my $hash (@hash) {
  no warnings 'uninitialized';
  print "$_ => $hash->{$_}\n" for
    map { $_->[0] }
    sort {
           $a->[1] cmp $b->[1]
        || $a->[2] <=> $b->[2]
        || $a->[3] <=> $b->[3]
        || $a->[4] <=> $b->[4]
    }
    map { [ $_, $hash->{$_}=~m!^(?:([a-z]+)(\d+)/)?(?:(\d+)/)?(\d+)$!i
+ ] }
    keys %$hash;
    print "-","\n";
}
__END__
2 => Gi1/0/0
1 => Gi1/0/1
3 => Gi1/1/1
4 => Gi2/0/0
5 => Gi2/0/1
-
1 => 1
2 => 2
3 => 3
4 => 4
5 => 5
-
4 => 1/1
5 => 1/2
1 => 2/1
2 => 4/5
3 => 15/1
-
1 => Fa0/1
2 => Fa0/2
3 => Fa3/1
5 => Gi0/0
4 => Gi0/1
-
[download]