>Excuse the late entry into this, but what is the problem with only one
>ethernet address for all interfaces?

The problem is if they are both on the same subnet or switch, it
is not possible to distinguish them.  This isn't normally a problem,
as multiple interfaces on a shared media doesn't make a lot of sense.

While ethernet addresses are not required to be globally unique (I believe),
they MUST be unique for the network.

I do not know if Zynx and Cogent actually reserve one address for each
interface or just one total, but the normal thing is to simply increment
the address you have once for each additional interface.

>AFAIK, e.g. Suns always use the same ethernet address for all their
>interfaces, don't they?

I don't know; in that case, you can't have multiple interfaces on the
same network, and need to be careful when connecting more than one
to a piece of equipment (routers, switches, etc).

Kevin