Re: A question for the oDAD draft spec.

["Nick 'Sharkey' Moore" <sharkey at zoic.org>]

G'day Theo,

> I was wondering though, that assuming in a net where the AR has to deal 
> with hundreds or thousands of nodes on the link (i.e. the replenishment 
> rate of new nodes - with the total staying roughly the same - (as the 
> case may be for mobile nodes under MIPv6), how is the AR supposed to 
> deal with 'remembering' the LLA of all the nodes' LLA if the overiding 
> flag is set to zero (O=0)?.

Well, it's not easy being a router.  Yes, if there's a collision with
an address which is already in the AR's NC, OptiDAD will fail ... see
Appendix A for a discussion of the probabilities of that, though.

> >	the AR simply sends an NS (from its unicast address) to the host,
> 
> when you say to the 'host' do you mean the solicited-nodes multicast 
> address or the unicast address of the host? This is a bit unclear from 
> the spec.

Solicited-nodes ... the AR doesn't know the LLA yet, so it has to 
solicit for it just like normal address resolution.

> Also can you see a potential denial of service attack if the node 
> decides to change optimistically its address continuously?

There's a heap of DoS opportunities against IPv6 address autoconf,
and this draft doesn't try to fix them ... see SEND for more details.

cheers,

-----Nick

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