Negative ARP caching [was Re: TCP session disconnection caused by Code Red? ]

Mon Aug 6 21:06:43 UTC 2001

>> Probably
>> a bad idea.  Rate limiting, as RFC 1122 suggests, would seem to be much
>> better.
>
> Agree that rate-limiting is a good idea (indeed that's INCOMPLETE[n] and
> [t1] in my proposal) but I don't see how it helps here.

Or to put it another way:

So if you are storing sufficient state in the OS to do rate-limiting (i.e.
keeping state on incomplete / nonexistant entries too), then put it to
some use, and (say) halve the rate-limit every time one proves
non-existant (and you drop the queued packet(s)), (i.e. twice as
many seconds between ARP packets), down to some minimum, like one
every 5 mins, and reset the rate limit on reception of any IP
packet from that machine and/or successful ARP.

This is almost the same thing as I suggested, but looks more like
rate limiting, with some intelligence as to the rate.

--
Alex Bligh
Personal Capacity