On Tue, 2 May 2000, Matthew Dharm wrote:
> On Tue, 2 May 2000, Tim Coleman wrote:
>
> > Isn't there a problem with this in that it is possible (although not
> > necessary all that likely) for two nics to have the same MAC address?
>
> My understanding on this was that it's not possible... the first byte or
> two is assigned to a manufacturer and the rest is supposed to be unique
> within that manufacturer. So all MAC addresses should be unique.
For Ethernet, yes - in theory. (I've found at least one card which worked
perfectly well, despite having a MAC address hardwired to
00:00:00:00:00:00. It was even getting an IP address via DHCP OK...)
On Token Ring, ISTR [part of] the MAC address is user-configurable?
Using MAC addresses to track interfaces should be fine, provided it will
fail gracefully (and has a reliable fallback) when confronted with two or
more identical cards. If, OTOH, the code will barf horribly (go into
Penguin Meditation, crash/BUG/Oops) there's a big potential problem here.
Has anyone else had this problem with an NIC, BTW? I must admit to having
been a bit surprised by it, when I saw the client's MS DHCP server had
issued an IP to that MAC address...
James.
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