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Re: DAD question

Brian E Carpenter <brian.e.carpenter@gmail.com> Sun, 12 August 2012 07:19 UTC

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Date: Sun, 12 Aug 2012 08:19:47 +0100
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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To: Karl Auer <kauer@biplane.com.au>
Subject: Re: DAD question
References: <36AA0AF8-95FD-4751-AE2E-A7A3D07038EB@cisco.com> <409F28A1-7974-4524-893D-CEF349A96657@employees.org> <5FAE0128-DDE7-45C4-8632-F56EAA1BE362@gmail.com> <20120811.180104.41668882.sthaug@nethelp.no> <1344721144.6453.29.camel@karl>
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On 11/08/2012 22:39, Karl Auer wrote:
> On Sat, 2012-08-11 at 18:01 +0200, sthaug@nethelp.no wrote:
>> Duplicate MAC addresses are regularly seen in the wild.
> 
> It's important to remember that DAD is link local. It is only checking
> whether the same address occurs on the local link. Duplicate MAC
> addresses are not actually a problem as long as the duplicates are not
> on the same link. 

I think they are a problem for sites that register MAC addresses and
use them as a first-line authentication mechanism. Obviously that is very
weak from a security point of view, but it's common practice.

   Brian

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