[click] ether address annotations...

[Eddie Kohler]

> would it be a good idea to add support for an ethernet address 
> annotation, ala IP?

I think so! But probably not if it's separate from the existing space for
address annotations.

I've added, to class Packet, a function 'addr_anno()' that returns a
"uint8_t *". This points to Packet::ADDR_ANNO_SIZE == 16 bytes of space for
an address annotation. All address annotations share the same space -- ip4,
ip6, etc.

So you could make a macro DST_ETHER_ANNO(p), that cast p->addr_anno() into
an EtherAddress*.

love,
ed