i'm a bit confused by the lines commented out. btw on the documentation on cpan about XML::Simple at the very beginning (QUICK START) it's explained how to get to the second level and further:

print $config->{server}->{kalahari}->{address}->[1];
[download]

so in your case, you can do something like

$data->{PairedDevices}->{DeciveA}->{DeviceNickName}
[download]

will return 'SD130' i have no knowledge about snmp so for that i must pass Oha