my %hash = ( network_type_1 => { conn_type_1 => [ 1 ],
                                 conn_type_2 => [ 2 ] },
             network_type_2 => { conn_type_1 => [ 3 ],
                                 conn_type_2 => [ 4 ] } );
# To get at the elements:
print $hash{ $network }->{ $connection }->[ $pos ];