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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: TCP session disconnection caused by Code Red?
Alex Bligh wrote: > 1. RFC826 appears to mandate only positive ARP caching. I can't > see a reason why negative ARP caching shouldn't work this > way: > > Keep only one ARP request in flight at a time. Retry ARPs > a maximum of [5] times, separated by at least [1] second. > After that, cache non-existance of a h/w address for that > IP address for normal positive caching time. The immediate problem with this is that it requires a *MUCH* larger ARP cache. Rather than needing enough memory for a couple of thousand active entries (the current norm for middle-of-the road routers), you need enough room for every possible address on every attached segment. [unsubstantiated conjecture] This may be what's killing the cable networks. If they are making room in the NAS ARP caches for the addresses that are being probed, then they are making room by flushing the "real" ARP entries, resulting in a constant flush/load cycle. [/uc, but exemplary of the problem with negative ARP caching.] --- Eric A. Hall http://www.ehsco.com/ Internet Core Protocols http://www.oreilly.com/catalog/coreprot/
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