Re: DAD question

On 8/11/12 8:36 AM, Bob Hinden wrote:
> Ole,
>
> On Aug 11, 2012, at 1:33 AM, Ole Trøan wrote:
>
>> Fred,
>>
>>> Call this "making sure I'm on the same page as anyone else"…
>>>
>>> RFC 4941 describes privacy addresses, and RFC 4291 describes an EID based on a MAC Address. RFC 4862 describes stateless address autoconfiguration, and uses RFC 4861's duplicate address detection mechanism.
>>>
>>> My question is: what happens if any of them discovers that it has created an address that is already in use in the network?
>>>
>>> There would appear to be two options:
>>> (1) "ah, OK, I guess I didn't really want to talk today"
>>> (2) Following RFC 4941, guess again until one creates a unique address
>>>
>>> Is it fair to assume that implementations do DAD and follow (2)?
>> implementations I'm familiar with do 1.
>> 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.
>
> For example, has any seen any actual duplicate MAC addresses?  It would be good to collect some data.
Most sun machines that I recall had the same mac address on all interfaces.

Duplicate macs are generally in my experience the product of deliberate 
configuration, cloning virtual machines or similar activity.
> Bob
>
>> cheers,
>> Ole--------------------------------------------------------------------
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