#!/usr/bin/perl
use strict;
use warnings FATAL => 'uninitialized';
use XML::Simple qw(:strict);
use Data::Dumper;

$| = 1;

my %ref;

# create 1st node
push(@{$ref{'node'}},{
  'id'   => 'net_1.2.3.0',
  'desc' => ['network'],
});

# create 2nd node
push(@{$ref{'node'}},{
  'id'   => 'ip_1.2.3.4',
  'desc' => ['ipaddr'],
});

my $xmlParser = XML::Simple->new();

my $fh;open $fh,'>','testfile.xml' or die "$!";

$xmlParser->XMLout(\%ref,(
  'XMLDecl'    => '<?xml version="1.0" encoding="utf-8"?>',
  'NoAttr'     => 0,
  'KeepRoot'   => 0,
  'RootName'   => 'test',
  'OutputFile' => $fh,
  'AttrIndent' => 1,
  'KeyAttr'    => { 'node' => 'id' },
));

print Dumper \%ref;

##</code><code>##

$VAR1 = {
          'node' => [
                      {
                        'desc' => [
                                    'network'
                                  ],
                        'id' => 'net_1.2.3.0'
                      },
                      {
                        'desc' => [
                                    'ipaddr'
                                  ],
                        'id' => 'ip_1.2.3.4'
                      }
                    ]
        };

##</code><code>##

<?xml version="1.0" encoding="utf-8"?>
<test>
  <node id="net_1.2.3.0">
    <desc>network</desc>
  </node>
  <node id="ip_1.2.3.4">
    <desc>ipaddr</desc>
  </node>
</test>