Re: IPv6 Routing & ND vs. Addressing, (Was: Re: <draft-ietf-6man-rfc4291bis-09.txt>)

Brian,

DAD is not robust. Last time I tried on the IETF wireless network 1 time in 4 DAD failed to detect a duplicate. 

Happy if anyone could do a more thorough experiment. 

Cheers 
Ole

> On 15 Jul 2017, at 23:01, Brian E Carpenter <brian.e.carpenter@gmail.com> wrote:
> 
> On 16/07/2017 01:39, Philip Homburg wrote:
>>> This is backwards. The goals of pseudo-random IIDs are to reduce the
>>> probability that scanning attacks find hosts, and to reduce the risk
>>> of IIDs being used to breach privacy.
>>> 
>>> If these goals are met, the collision probability will in any case
>>> be low, so DAD failure will be exceedingly rare.
>> 
>> I completely disagree. A collision is fatal. We are nowhere near transparently
>> handling all collisions. At best we can hope that DAD can make one node
>> continue unaffected.
> 
> I'm confused.
> 
> Firstly, do we have any experimental evidence that collisions
> are a real operational problem? (Obviously, MAC address collisions are
> disastrous at layer 2 anyway, so although IPv6+(Modified EUI-64) needs to
> detect them, they are irrelevant to the current discussion.)
> 
> Secondly, if a collision does occur with IPv6+(pseudo-random IID),
> recovery is obvious: after DAD failure, generate a new pseudo-random
> IID and try again. This is perfectly compatible with RFC4862 section 5.5
> and is specfied in RFC7217 for stable IIDs and in RFC4941 for privacy
> addresses.
> 
>    Brian
> 
>> 
>> In contrast, people have been scanning my IPv4 ranges for the past 20 years
>> or so. That may be annoying. That may amplify attacks opportunities. But
>> in it self it is not fatal.
>> 
>> 
>> .
>> 
> 
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