I used Authen::SASL::Perl::GSSAPI and came up with this:

#!/usr/bin/perl

use strict;
use warnings;
use Net::LDAP;
use Authen::SASL;

my $adhost    = 'http://localhost';
my $ldap_base = 'dc=brbdc1,dc=net';

my $sasl = Authen::SASL->new( mechanism => 'GSSAPI' );
my $ldap;

eval {
    $ldap = Net::LDAP->new($adhost,
                           onerror => 'die')
      or die "Cannot connect to LDAP host '$adhost': '$@'";
    $ldap->bind(sasl => $sasl);
};

print "\tLDAP bind() succeeded, working in authenticated state\n";
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