Another suggestion:

#!/usr/bin/perl -w
use strict;
use Socket;

my %HoA;

while (<DATA>) {
    chomp;
    my ($swit, $server, $ip_range) = split;
    my ($start_ip, $end_ip) = map unpack("N", inet_aton($_)), split /-
+/, $ip_range;

    my $name = "${swit}_$server";
    for ($start_ip .. $end_ip) {
        push @{ $HoA{$name} }, inet_ntoa(pack "N", $_);
    }
    
}
use Data::Dumper;
print Dumper \%HoA;

__DATA__
server    1    10.1.1.1-10.1.1.5
server    2    192.168.1.1-192.168.1.5
server    1    192.168.1.1-192.168.1.2
[download]

$VAR1 = {
          'server_2' => [
                          '192.168.1.1',
                          '192.168.1.2',
                          '192.168.1.3',
                          '192.168.1.4',
                          '192.168.1.5'
                        ],
          'server_1' => [
                          '10.1.1.1',
                          '10.1.1.2',
                          '10.1.1.3',
                          '10.1.1.4',
                          '10.1.1.5',
                          '192.168.1.1',
                          '192.168.1.2'
                        ]
        };
[download]