Instead of reading a 'line' at a time read a 'record' at a time. Set $/ to the record separator ("-------------------------\n" in this case) and away you go:

use strict;
use warnings;
use Data::Dump;

local $/ = "-------------------------\n";
my @records;

while (<DATA>) {
    chomp;

    next unless length;
    push @records, [split "\n"];
}

print Data::Dump::dump (\@records);


__DATA__

[download]

Given the data supplied by the OP prints:

[
  [
    "Device ID: HS-IDF3-C3550-A.B.org",
    "Entry address(es):",
    "  IP address: 10.x.x.x",
    "Platform: Cisco WS-C3550-12G,  Capabilities: Router Switch IGMP",
    "Interface: GigabitEthernet3/1,  Port ID (outgoing port): GigabitE
+thernet0/2",
    "Holdtime : 158 sec",
    "",
    "Version :",
    "Cisco IOS Software, C3550 Software (C3550-IPSERVICES-M), Version 
+12.2(25)SEE, RELEASE SOFTWARE (fc2)",
    "Copyright (c) 1986-2006 by Cisco Systems, Inc.",
    "Compiled Thu 02-Feb-06 20:37 by antonino",
    "",
    "advertisement version: 2",
    "Protocol Hello:  OUI=0x00000C, Protocol ID=0x0112; payload len=27
+, value=00000000FFFFFFFF010221FF0000000000000005313DD680FF0000",
    "VTP Management Domain: ''",
    "Duplex: full",
    "Management address(es):",
    "  IP address: 10.x.x.x",
  ],
  [
    "Device ID: HS-IDF3-C3550-A.B.org",
    "Entry address(es):",
    "  IP address: 10.x.x.x",
    "Platform: Cisco WS-C3550-12G,  Capabilities: Router Switch IGMP",
    "Interface: GigabitEthernet2/1,  Port ID (outgoing port): GigabitE
+thernet0/1",
    "Holdtime : 138 sec",
    "",
    "Version :",
    "Cisco IOS Software, C3550 Software (C3550-IPSERVICES-M), Version 
+12.2(25)SEE, RELEASE SOFTWARE (fc2)",
    "Copyright (c) 1986-2006 by Cisco Systems, Inc.",
    "Compiled Thu 02-Feb-06 20:37 by antonino",
    "",
    "advertisement version: 2",
    "Protocol Hello:  OUI=0x00000C, Protocol ID=0x0112; payload len=27
+, value=00000000FFFFFFFF010221FF0000000000000005313DD680FF0000",
    "VTP Management Domain: ''",
    "Duplex: full",
    "Management address(es):",
    "  IP address: 10.x.x.x",
  ],
]

[download]
True laziness is hard work

In reply to Re: Split file output into array of arrays by GrandFather
in thread Split file output into array of arrays by spickles

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