How to show cluster ids on a physical network

I sincerely thank you all for trying to help. My final solution is as follows.

First I used tcpdump to gather the llt broadcasts and cut out the MAC addresses and the cluster IDs.

<code>tcpdump -a -X -c 1000 broadcast and ether proto 0xcafe 2>/dev/null |
sed -n '
/^[012][0-9]:/{
    s/^[^ ]* \([^ ]*\) .*/\1/
    h
    n
    s/^[  ][  ]*[^ ]*  *[^ ]*  *\([^ ]*\) .*$/\1/
    H
    g
    s/\n/ /
    p
}
' | sort -uk2</code>

This would actualy have been enough to answer my original question but I was curious which clusters have which IDs.

Then I used arp to gather the MAC addresses together with the IP information. Of course I needed to feed the arp cache on the local server first so I chose to use a SYN request in perl.

<code>function sshping
{
typeset -x SERVER=$1
typeset -x PORT=22
        [[ -n $2 ]] && PORT=$2

        /usr/bin/perl -w -e '
        use strict;
        use Net::Ping;
        use Socket;

        my $ip;
        my $host = $ENV{"SERVER"};;
        my $packed_ip = gethostbyname($host);
        if (defined $packed_ip) {
                        $ip = inet_ntoa($packed_ip);
        } else {
                        print "$host ssh port is unreachable.\n";
                        exit( 1 );
        }
        my $p = Net::Ping->new("tcp", 6);

        $p->{port_num} = $ENV{"PORT"};

        if( $p->ping($ip) ) {
          print "$host port $p->{port_num} is reachable.\n";
          exit( 0 );
        } else {
          print "$host port $p->{port_num} is unreachable.\n";
          exit( 1 );
        }
        '
}
i=1;while ((i<255)) ; do sshping 10.217.130.$i >/dev/null 2>&1 ; ((i+=1)) ; done</code>

Then I was ready for my arp requst.

<code>arp -a | tr -d '][)(' | sed -n '
        /ethernet/{
                s/\([ :]\)\([0-9]\)\([ :]\)/\10\2\3/g
                s/at //
                s/ ethernet .*$//
                p
        }
'</code>