This demonstrates how to parse such a file and extract the relevant info with regexes. You may tweak those to match the fields you want.

use strict;
use warnings;

use Data::Dumper;

my ($mac, %data);

while ( <DATA> )
{
    if ( /^Ethernet address: ([0-9a-f]{12}) \(([^\)]+)/ )
    {

        $mac = $1;
        $data{$mac}{device} = $2;
        next;
    }
    
    if ( /(Incoming|Outgoing) total ([0-9]+) packets/ )
    {
        $data{$mac}{$1} = $2;
        next;
    }
    
    if ( /Average rates: ([0-9\.]+) kbytes\/s incoming, ([0-9\.]+) kby
+tes\/s outgoing/ )
    {
        $data{$mac}{incomingRate} = $1;
        $data{$mac}{outgoingRate} = $2;
    }
        
}

print Dumper (\%data);
    
__DATA__
Ethernet address: 009096c7cf98 (ADSL Modem)
        Incoming total 297089 packets, 45056408 bytes; 293887 IP packe
+ts
        Outgoing total 401212 packets, 252051283 bytes; 398003 IP pack
+ets
        Average rates: 0.47 kbytes/s incoming, 2.63 kbytes/s outgoing
        Last 5-second rates: 0.00 kbytes/s incoming, 0.00 kbytes/s out
+going

Ethernet address: 0020ed7924c2 (Debian Router ext)
        Incoming total 401212 packets, 252051283 bytes; 398003 IP pack
+ets
        Outgoing total 297096 packets, 45056702 bytes; 293887 IP packe
+ts
        Average rates: 2.63 kbytes/s incoming, 0.47 kbytes/s outgoing
        Last 5-second rates: 0.00 kbytes/s incoming, 0.00 kbytes/s out
+going
[download]

Output:

$VAR1 = {
          '009096c7cf98' => {
                              'outgoingRate' => '2.63',
                              'incomingRate' => '0.47',
                              'Outgoing' => '401212',
                              'Incoming' => '297089',
                              'device' => 'ADSL Modem'
                            },
          '0020ed7924c2' => {
                              'outgoingRate' => '0.47',
                              'incomingRate' => '2.63',
                              'Outgoing' => '297096',
                              'Incoming' => '401212',
                              'device' => 'Debian Router ext'
                            }
        };
[download]