my $acl = {};
$acl->{source}  = []; 	       # array of Network address e.g, [10/8,172.16/16]
$acl->{dest}    = [];          # same as above
$acl->{original}= 'unknown';   # A string for original ACL e.g, permit ip any 10/8

# After I create a hash I will store the hash reference in an array

push @acl_grp, \%acl;

# After populating the array of hash refs I want to sort them
# I would do something similar to this

foreach $acl ( sort compare @acl_grp ){
    print $acl->{original},"\n";
}

# compare function is coded as
#   return -1 if $b is a supernet of $a
#   return 1 if $a is a supernet of $b
#   return 0 for all other cases, mimicking the behaviour of <=>
sub compare($$){some code};