Multicast Mac-Addresses

[admin_2]

is somewhere a list of multicast-mac addresses which are used on catalyst switches for different protocols (cdp,disl,vtp,uplink fast,dtp,bvst+)

[#2]

Here are some of the list of well-known MAC addresses used by the Catalyst Switches:

01-80-c2-00-00-xx -- Famous BPDU'S

01-00-00-0c-00-00 -- ISL

01-00-0c-cc-cc-cc --- CDP, DISL, DTP (Dynamic Trunk proto)- all of them use the same muliticast address, the difference is in the protocol id field.

CDP == PROTOCOL TYPE 0X2000

DTP == PROTOCOL TYPE 0X2004

The reason that all of them use the same multicast address is that the only kind of packets that are allowed to go thru on a blocked port (Spanning Tree) are CDP and BPDU's.