BPDUs

IEEE STP BPDU frame format

I've been working with this stuff lately. I find it interesting how things have evolved in networking. You can interpret certain things in a certain ways only otherwise the meaning
changes.

Here we have the IEEE STP BPDU packet encapsulated in a SNAP header.

The Destination Address on the ethernet frame identifies who in the broadcast media will receive the packet.

The MAC adress themselves are allocated by some bodies:
IANA has a list.
For multicast MAC address, refer to the list at Caverbear

Specific MACs are here:

01-00-0C-CC-CC-CC -802- CDP (Cisco Discovery Protocol), VTP (Virtual Trunking Protocol)
01-00-0C-CC-CC-CD Cisco PVST+ protocol
01-80-C2-00-00-00 -802- Spanning tree (for bridges)
01-80-C2-00-00-01
to
01-80-C2-00-00-0F -802- 802.1 alternate Spanning multicast