>>>>> On Thu, 5 Aug 2004 04:10:50 +1000,
>>>>> "Nick 'Sharkey' Moore" <[EMAIL PROTECTED]> said:
>> >> Note that I don't see a need to prohibit unsolicited NAs with O=0,
>> >> thus the text in section 3.1 regarding them is ok.
>> >> I just don't see them as useful hence we shouldn't recommend that they be
>> >> sent.
>>
>> > Yep, they're only useful in a particular circumstance, and that
>> > puts them fairly thoroughly beyond the scope of OptiDAD. I'd
>> > like to keep the rules about the O flag in 3.1, just to
>> > keep anyone who does implement this honest. Jinmei, would you
>> > be happy with this?
>>
>> To make it sure, I'm going to talk about the following bullet of
>> Section 3.1:
>>
>> * (adds to 7.2.6) The Optimistic node MAY send an unsolicited
>> Neighbour Advertisement to All Nodes when it first configures an
>> address. The Override flag on this advertisement MUST be cleared
>> (O=0).
>>
>> Hmm, I'd still like to remove this bullet, since I don't want to see
>> new implementations introduce the optimization just because it's a
>> "MAY", without considering the rationale and possible bad effects.
> Just to be sure, which possible bad effects do you mean?
Umm...I think I've explained this 100 times...basically, any operation
during the optimistic state which would not allow for pure-RFC2462
hosts can cause bad effects. And I basically mean all such effects in
this kind of context. In this particular case, sending an unsolicited
NAs can create an unnecessary neighbor cache on other nodes in the
link. If one of such nodes start to send packets to the optimistic
address and the address is actually a duplicate (i.e., another node
has been using the address), then the packets won't be delivered to
the legitimate node for some period.
I guess the reason why we have needed to this type of conversation so
many times is fundamental difference on the basic standpoint.
You tend to introduce as much convenience for optimistic nodes as
possible when the odds of its bad effect are small.
I tend to avoid any bad effect as much as possible as long as the odds
are non 0, however small they are, particularly when the additional
convenience is a kind of option for the optimistic behavior.
(But note that I've already admitted the difference is a controversial
point.)
JINMEI, Tatuya
Communication Platform Lab.
Corporate R&D Center, Toshiba Corp.
[EMAIL PROTECTED]
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