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Re: Route table growth and hardware to the filter

  • From: Jon Lewis
  • Date: Tue Sep 11 16:12:16 2007

On Mon, 10 Sep 2007, Stephen Sprunk wrote:

Sucks to be them.  If they do not have enough PA space to meet
the RIR minima, the community has decided they're not "worthy"
of a slot in the DFZ by denying them PI space.

Not true, there is an ARIN policy that allows you to get a /24 from one of your providers even if you only need 1 IP address:

If the PA /24 is under 199/8 or 204-207/8, then the filters being discussed would allow their advertisement through, because ARIN's minimum allocation for those blocks is /24. In ARIN's 22 other /8s, the filters would not because the minimum is /20 (or /22, for 208/8).

As long as enough NSPs don't filter on RIR minimums, there's still a pretty good chance that when a small PA multihomer's IP space provider's connection is down, traffic routed towards that provider will get rerouted to their other provider(s).

Breaking PA /24 multihoming would be unfortunate collateral damage.

Perhaps someone could use the data from the cidr-report and RIRs to create a precision targeted prefix-list intended just to block unnecessary more specifics rather than across the board on RIR minimums?

You could even do two different versions. A loose version that just throws out covered subnets with same as-path and a BOFH version that throws out all apparently gratuitous subnetting smaller than RIR minimums, but not all smaller than RIR minimum routes.

I just wonder how huge the list would be and what the CPU and config size damage would be.

 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
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