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Re: Is it time to abandon bogon prefix filters?
On Mon, 25 Aug 2008 09:38:00 EDT, Chris Marlatt said: > IIRC "bogon" is specific to unallocated space. Whether it be advertised > or not should not matter. Right. Tell that to everybody who's ever been at the wrong end of a bogon filter for 69/8, 70/8, 71/8... I'll go out on a limb and say that if you see a BGP announcement for a prefix you think is a bogon, it's *more* likely that the space is no longer unallocated and you didn't get the memo, than it's still unallocated but being pirated by somebody. (Which raises a question - what % of sites that are doing bogon filtering but *not* listening to something like Team Cymru's bogon feed? If it's nearly ubiquitous, it's not a big problem. But given the number of places that have problems with bogon filters, only a small percentage seem to be doing so...) At the point that you're doing bogon filtering, you have no way to disambiguate those two cases. Which is why I said it's a BGP announcement filtering issue.