01-00-0c-cc-cc-cc

[dknov]

Hi,

A quick question. Do you see 01-00-0c-cc-cc-cc system MAC address as being broadcast or multicast?

I can find arguements to both, but I am interested to hear more opinions.

Thanks,

David

[a.alekseev]

http://en.wikipedia.org/wiki/Multicast_address

[a.alekseev]

01-00-0C-CC-CC-CC 0x0802 CDP (Cisco Discovery Protocol), VTP (Virtual Trunking Protocol)

[andrew.burns]

Hi,

You can directly look this up in the IEEE 802.3 standard documents. (Section 1, sub-section 3.2.3.1), to quote:

All 1's in the Destination Address field shall be predefined to be the Broadcast Address.

So, to answer the question, you can say that 01-00-0c-cc-cc-cc is definitely not a broadcast address (because it's not all 1's). However, as the I/G bit is 1 it is a group (or multicast) address. (The broadcast is a sub-type of multicast - but the reverse isn't true)

HTH

Andrew.