On Apr 4, 2010, at 11:46 17AM, Jonathan Lassoff wrote:
> Excerpts from John Peach's message of Sun Apr 04 08:17:28 -0700 2010:
>> On Sun, 4 Apr 2010 11:10:56 -0400
>> David Andersen <[email protected]> wrote:
>>
>>> There are some classical cases of assigning the same MAC address to every
>>> machine in a batch, resetting the counter used to number them, etc.;
>>> unless shown otherwise, these are likely to be errors, not accidental
>>> collisions.
>>>
>>> -Dave
>>>
>>> On Apr 4, 2010, at 10:57 AM, jim deleskie wrote:
>>>
>>>> I've seen duplicate addresses in the wild in the past, I assume there
>>>> is some amount of reuse, even though they are suppose to be unique.
>>>>
>>>> -jim
>>>>
>>>> On Sun, Apr 4, 2010 at 11:53 AM, A.B. Jr. <[email protected]> wrote:
>>>>> Hi,
>>>>>
>>>>> Lots of traffic recently about 64 bits being too short or too long.
>>>>>
>>>>> What about mac addresses? Aren't they close to exhaustion? Should be. Or
>>>>> it
>>>>> is assumed that mac addresses are being widely reused throughout the
>>>>> world?
>>>>> All those low cost switches and wifi adapters DO use unique mac addresses?
>>>>>
>> Sun, for one, used to assign the same MAC address to every NIC in the
>> same box.
>
> I could see how that *could* work as long as each interface connected to
> a different LAN.
>
> Maybe the NICs shared a single MII/MAC sublayer somehow? I've never
> borne witness to this though.
There was a socketed ROM IC with the *machine's* MAC address on the
motherboard, way back when. If your motherboard needed replacing, the tech
would move that IC to the replacement.
Why was this done? The reason was simple: compatibility with other stacks.
Remember that circa 1988-1990, it was not obvious that TCP/IP was going to be
the winner.
--Steve Bellovin, http://www.cs.columbia.edu/~smb
