North American Network Operators Group
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Re: BGP Filtering

  • From: Joe Abley
  • Date: Tue Jan 15 12:26:02 2008


On 15-Jan-2008, at 11:40, Ben Butler wrote:

Defaults wont work because a routing decision has to be made, my transit
originating a default or me pointing a default at them does not
guarantee the reachability of all prefixes..

Taking a table that won't fit in RAM similarly won't guarantee reachability of anything :-)

Filter on assignment boundaries and supplement with a default. That ought to mean that you have a reasonable shot at surviving de-peering/ partitioning events, and the defaults will pick up the slack in the event that you don't.

For extra credit, supplement with a bunch of null routes for bogons so packets with bogon destination addresses don't leave your network, and maybe make exceptions for "golden prefixes".

I am struggling to see a defensible position for why just shy of 50% of
all routes appears to be mostly comprised of de-aggregated routes when
aggregation is one of the aims RIRs make the LIRs strive to achieve. If
we cant clean the mess up because there is no incentive than cant I
simply ignore the duplicates.

You can search the archives I'm sure for more detailed discussion of this. However, you can't necessarily always attribute the presence of covered prefixes to incompetence.


Joe