Draw your data out on a piece of paper with a box around each data item (nested as appropriate). Where sensible give boxes names.

Each named box is a key/value pair and should be in a hash. Each unnamed box is an array element. The nesting of the boxes tells you how the hash and array elements nest.

Keep your piece of paper around to refresh you understanding of how the data hangs together as you write the code. At each point that you need to access something you need to work from the outermost box to the box of interest taking note of whether each box is an array element or a hash value.

use warnings;
use strict;

my %vlan_nums = (
        112 => {
                name        => "JP-WIRELESS",
                description => "JP-WIRELESS",
                ip          => "192.168.207.1",
                mask        => "255.255.255.0"
            },
        2113 =>
            {
                name        => "JP-IDF1-DATA",
                description => "JP-IDF1-DATA",
                ip          => "10.136.113.1",
                mask        => "255.255.255.0"
            }
);

for my $num (sort keys %vlan_nums) {
    print <<EOF;
VLAN number     : $num
VLAN name       : $vlan_nums{$num}{name}
VLAN description: $vlan_nums{$num}{description}
VLAN ip         : $vlan_nums{$num}{ip}
VLAN mask       : $vlan_nums{$num}{mask}

EOF
}
[download]

Which prints out:

VLAN number     : 112
VLAN name       : JP-WIRELESS
VLAN description: JP-WIRELESS
VLAN ip         : 192.168.207.1
VLAN mask       : 255.255.255.0

VLAN number     : 2113
VLAN name       : JP-IDF1-DATA
VLAN description: JP-IDF1-DATA
VLAN ip         : 10.136.113.1
VLAN mask       : 255.255.255.0
[download]

Data::Dumper is also handy for displaying Perl data structures.

toolic -

You nailed it. I was reading the perl doc you linked for a couple of hours before posting, so I was on the right track. But decoding all of those parenthesis, brackets, commas, etc. can get confusing quickly. So now my question would be how to add a new vlan?

to add a new vlan assuming vlan number is unique

unless (exists $vlan_nums{$new_num}){
$vlan_nums{$new_num}{name} = xyz;
....
}
[download]

If update is needed for the existing number you can add an else loop