On 7 feb 2011, at 17:15, Jay Ashworth wrote:

>> Ok, I had a hard time making up my mind whether a sarcastic or a
>> factual response was in order...

> I see you decided to go with "sarcastic".

Not sure if Owen noticed...  :-)

> I'm sure it's clear to you that "no one's doing it now" is not a valid
> response to prophylactic secure network planning...

Well, no and yes. There's only a few panes of glass keeping people out of most 
houses. We know glass is easy to break. We know it gets broken and people get 
in who aren't wanted there once in a while. Still only a few people see the 
need to install steel bars in front of their windows.

In real life we take risks all the time. In the networked world somehow it 
always has to be all or nothing, with few people occupying the reasonable 
middle ground.

But in this case, we know there's a potential problem and waiting for it to 
become acute is not the best approach.

> So, you're not going to actually address the problem seriously?

Vendors should modify their neighbor discovery implementations such that it 
still works even when large numbers of addresses are scanned. The easiest way 
would be to keep only a limited number of incomplete ND cache entries and throw 
those away on an LRU base, but create a full ND cache entry that is kept around 
when a neighbor advertisement is received, even if there is no incomplete ND 
cache entry at that time. AFAIK the incomplete ND cache entries don't do 
anything we can't do without.

"Solving" this with NAT is the classic example of shooting a mosquito with a 
canon.

I also don't think any protocol modifications are necessary.

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