[28849] in North American Network Operators' Group
BGP filtering of supernets out of classful space
daemon@ATHENA.MIT.EDU (Jeff Haas)
Fri May 19 11:49:32 2000
Date: Fri, 19 May 2000 11:47:06 -0400
From: Jeff Haas <jeffhaas@merit.edu>
To: NANOG <nanog@merit.edu>
Message-ID: <20000519114704.A6466@vorlon.merit.edu>
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In attempting to help someone with regards to BGP announcement
filtering from the IRR we've found the following situation:
A provider in China has been assigned addresses in the
traditional class C space. APNIC's assignment is a /16 for this allocation.
Said provider, trying to be good Internet citizens are announcing
only aggregates of /16.
However, they're running into several providers that are filtering
the announcements because they aren't /24. Experimentation has
proven that announcing /24's will solve this problem. This obviously
clutters up the global routing tables.
The primary justification I can see for such filtering is to prevent
"sink routing" - or catching everything else where more specific routes
don't exist. (This would probably be a Bad Thing for the provider
foolishly making such announcements - a very effective self DoS attack.)
What methodology are providers using for these types of route
filtering issues now?
(I'll save the IRR pulpit for later.)
And yes, I have directed the provider having the routing issues to
contact each ISP doing the filtering separately.
--
Jeffrey Haas - Merit RSng project - jeffhaas@merit.edu
