Steinar, On Aug 11, 2012, at 9:01 AM, [email protected] wrote:
>>> 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). Interesting. Are these different machines/interfaces with the same Mac addresses, or the same machine connecting via some other path or location. My question was about machines/interfaces. That is, are we seeing manufacturing mistakes, etc.? Thanks, Bob > > 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 --------------------------------------------------------------------
