> > it may be a fair assumption that if an address based on the MAC address is > > duplicate, the MAC address itself is a duplicate. > > True, but the odds of this happening are very low. I wonder if we have any > data on DAD detecting duplicate addresses and their cause.
You may need to qualify "very low". > For example, has any seen any actual duplicate MAC addresses? It would be > good to collect some data. Duplicate MAC addresses are regularly seen in the wild. As an example, from a nearby DHCP server, I have the following duplicates from a total of 65499 MAC addresses: 5 00:90:4c:91:00:01; 3 00:40:10:20:00:02; 3 00:00:00:00:00:00; 2 bc:b1:f3:61:28:e3; 2 98:0c:82:84:ef:83; 2 34:21:09:03:76:f9; 2 00:1f:1f:8c:d4:d5; 2 00:1f:1f:8c:d4:cd; 2 00:1d:73:11:11:13; 2 00:11:22:33:44:56; So from this sample a total of 10 MAC addresses occur more than once (different customers, different locations). I make no claims about these numbers being representative. My main point is that duplicates *occur*, for several different reasons, e.g. - Manufacturing mistakes - Software bugs - MAC address explicitly set Steinar Haug, Nethelp consulting, [email protected] -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
