use XML::LibXML;
my $xml = XML::LibXML->new->parse_fh(\*DATA);
foreach my $station ($xml->findnodes('/servers/*'))
{
	printf("Station: %s\n", $station->tagName);
	
	foreach my $ip ($station->findnodes('./ip'))
	{
		printf("\tIP: %s\n", $ip->textContent);
	}
}
__DATA__
<servers>
         <station18>
                 <ip>10.0.0.101</ip>
                 <ip>10.0.1.101</ip>
                 <ip>10.0.0.102</ip>
                 <ip>10.0.0.103</ip>
                 <ip>10.0.1.103</ip>
         </station18>
         <station19>
                 <ip>10.0.0.111</ip>
                 <ip>10.0.1.111</ip>
                 <ip>10.0.0.112</ip>
                 <ip>10.0.0.113</ip>
                 <ip>10.0.1.113</ip>
         </station19>
         <station17>
                 <ip>10.0.0.121</ip>
                 <ip>10.0.1.121</ip>
                 <ip>10.0.0.122</ip>
                 <ip>10.0.0.123</ip>
                 <ip>10.0.1.123</ip>
         </station17>
         <station20>
                 <!-- no IP addresses -->
         </station20>
         <station21>
                 <!-- just one IP address -->
                 <ip>10.2.1.123</ip>
         </station21>
</servers>