Zero MAC address

[Chuck Swiger]

On Mar 14, 2012, at 4:05 PM, Adarsh Joshi wrote:
> Thank you for the quick replies.
> 
> I am aware of the importance of the second bit. By invalid, I was wondering if that particular address is reserved or if it has any special meaning or purpose.

There isn't a special meaning for all-zeros MAC to my knowledge, although all-ones MAC is subnet-local broadcast.

> So in theory, I cannot classify it as an invalid MAC address on my packet statistics utility.

Yes, as far as theory goes.  In practice, all-zeros MACs tend to indicate that an ethernet driver failed to read the burned-in MAC assigned to the NIC.  :-)

> On a side thought, can an incoming packet be classified as "invalid MAC address" if it has the same MAC address of the host?

Tentatively, yes-- MACs are supposed to be unique, and any collision is bad...just be careful that you aren't seeing packets which your local host had sent (perhaps because of a L2 switching loop).

Regards,
-- 
-Chuck