Normal? No, this goes against a lot of
things networking, so definitely not kosher. Two mac's in a
broadcast domain is an extremely bad thing usually causing a
switch to start flooding unicast traffic within a vlan. Microsoft
thought this was a great way to do redundancy with Network
Load-Balancing replicating macs among cluster members until
network people realized it was breaking their lans (essentially
turning switches into hubs). I have some mega-outages I can
attribute to this commonly over the years...
Does it happen? Sure - as chinese companies clone each other and
other legit vendor hardware apparently eeprom data and all, not
bothering to register an oui id themselves, I'm not entirely
surprised. Buy those $5 ebay generic nics in bulk, i'm sure
you'll start getting mac collisions.
Another reason to stay with reputable sources of hardware...
I'd be curious what hardware it is being cloned indiscriminately,
as would whoever owned the rights to the registered OUI.
https://www.wireshark.org/tools/oui-lookup.html
-mb
On 02/06/2014 04:50 PM, Daniel Stasinski wrote:
The past few days I've been trying to solve a mystery.
I've run a disability chat room for 17 years now and the whole time we
have had our own custom chat client that connects to a customized
ircd. For the identd portion of the connect, I have always used an 8
digit random number but as of v3 of the client, I seeded the random
number generator with their MAC address so their identd would be the
same if they re-installed. I have always been under the impression
that no two devices would ever share the same MAC. Note that this
isn't a security issue for the site, it's just a convenience thing for
me.
In the last couple of months, 4 people have come in with duplicate
id's. This has never happened before. Finally today a new guy came
in and he turned out to be a programmer too so we talked about it and
he gave me his pc's mac address. 58-2c-80-13-92-63. On a whim, I
googled it and holy crap!
I'm going to switch algorithms but I'm still curious, is it normal for
vendors to recycle MAC addresses?
Daniel