Assuming unique MAC addresses is a very poor assumption.
At one company I worked at we once received a huge shipment of ethernet cards (several thousand) that all had the same MAC address. We didn't realize it until customers who had purchased multiple pieces of equipment began to call in.
I've heard several similar anecdotes from other engineers at other companies.
Yeah, very bad assumption.
Can confirm that this is a bad idea as manfuarcturing defects do happen. Took a shipment of brand new NetApp toasters this year and they all had the same WWN/WWPN's!
Needless to say NetApp where quite embarrassed and we are glad that we noticed it in pre-prod otherwise it could have been quite bad.
Re:How long do GUIDs really need to be?
by thethimble on Friday October 31, 2014 @06:22PM
(#8541393)
A lot of platforms (iOS) also spoof MAC addresses too
The spoofing happens when talking to other devices (not themselves); i.e., there is some layer of the device that knows its true MAC address and the UUID generation code should use that layer.
Well until 5236-03-31 21:21:00 UTC (assuming my calculations are correct) using v1 UUIDs and assuming unique MAC addresses and no race conditions.