BPDU mac address

http://www.cisco.com/warp/public/473/127.html

when BPDU for STP (spanning tree protocol) is used,
the source mac address is the port mac address assigned by
cat 6k.

CatOS command: show port mac-address 2/7
IOS command: show interface fastEthernet 4/1

The reason of having diff mac address for each port for BPDU
is to detect any problem on the etherchannel where multi
ports are grouped into a channel and treated as a single port
in STP.