Have you ever tried to diagnose a VLAN related issue on a VIO server and tried to find out if a particulare VLAN tag is being seen by the VIO servers SEA adapter?  This little piece of code will be most helpful to you.  I know this works with Cisco switches, please leave a comment if this works with other switches.  Thanks.

Set the SEA Variable

SEA=en4

Bring the SEA adapter up so you can see the packets on the SEA adapter.

ifconfig ${SEA} up

Using tcpdump and perl:

tcpdump -nX -i ${SEA} vlan and ether dst 01:00:0c:cc:cc:cd | perl -ne '$t=time();$st||=$t;if (/0x0000:?\s+.(...)/) { $h=hex($1);if (!$d{$h}) {$d{$h}=1;printf STDERR "%5d VLANs: %s\n",($t-$st),join(",",sort {$a<=>$b} keys %d);}}'

These tcpdump and perl commands are better and more reliable.

tcpdump -i ${SEA} -xx ether multicast | perl -e '$st=time();while () { if (/^\s+0x[0-9a-f]+:\s+(.*)/) {$s.=$1;$s=~s/\s+//g; next; }($h,$s)=($s,"");if ($h =~ /.{24}(.{4})(....).{22}(....)/) { $n=1;$v=$3;if ($1 eq "8100") {$v=$2;$n=0;} $v=hex($v)&0xfff; $h{$v.($n?"(n)":"")}=$n; }$l=join(",",sort {$a<=>$b} keys %h);if ($ol ne $l) { $ol=$l;printf "%3d: Vlans: %s\n",time()-$st,$l; } }'

You will get some output like this, which are all the VLANs your SEA adapter sees from the switch ports:

1 VLANs: 140,142,210,224,227,315,318,319,321,324

When finished, bring the SEA adapter to a detached state.

ifconfig ${SEA} detach