G'day Jinmei,
the other email covers your other points, these are the two
I left out last time.
> 3. I don't think the advantage for the optimistic node when two nodes
> simultaneously perform DAD is justified (Section 4.3).
>
> This gives the Optimistic Node a slight advantage
> over Standard nodes, however this is justified since the Optimistic
> node may have already established connections to Optimistic
> Addresses.
Remember, this is for the case where two nodes are configuring the
same address at the same time. Given the odds of an address collision
are already vanishingly small, the odds of a simultaneous collision
of this sort are microscopic.
> As we discussed in rfc2462bis, address duplication may in some cases
> indicate hardware address duplication. Since continuing operation
> under hardware address duplication can cause additional confusing
> situation (even if one of the colliding node stops using the
> duplicate IP address), I think no exception can be justified.
If there's an actual LL address duplication, we've got bigger
problems than worrying about the exact balance of probabilities
in DAD.
> Additionally, we should have assumed actual duplication for an
> optimistic address is very unlikely to happen. If so, giving
> advantage under a nitch duplicate condition does not seem to provide
> much actual benefit.
>
> So, I'd request to simply remove the special privilege.
The reason it's there is to tip the balance in favour of the current
user of an address rather than the newcomer. The behaviour fits in
with the idea that OptiDAD is promoting the address to non-Tentative ...
non-Tentative addresses are defended rather than surrendered.
-----
> 10. In section 3.2
>
> * (modifies 5.4.3) A node MUST reply to a Neighbour Solicitation for
> its address from the unspecified address with a Neighbour
> Advertisement to the All Nodes address. If the solicitation is
> for an Optimistic Address, the reply MUST have the Override flag
> cleared (O=0).
>
> Does the first sentence apply to all nodes including "Standard" ones,
> or is it limited to optimistic nodes? (I'd object to this
> modification in the first place, BTW - see comment 5).
OptiDAD draft does not prescribe ANY changes to behaviour for
Standard Nodes. It is designed to interoperate with any nodes
following the rules of 2461/2462, although it doesn't offer any
benefit unless the RS includes a SLLAO.
Which reminds me: any idea what the timetable for 2461bis/2462bis is
looking like? I guess OptiDAD should be updated one they are finalized.
-----Nick
--
Nick Moore, Resarch Fellow | <[EMAIL PROTECTED]>
Monash University CTIE | <http://www.ctie.monash.edu.au/ipv6/>
Australian Telecommunications CRC | <http://www.telecommunications.crc.org.au/>
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