[FoRK] filtering /48 is going to be necessary

Adam L Beberg beberg at mithral.com
Sun Mar 11 11:06:35 PDT 2012

Or they could just use geographic prefixing and make the problem trivial.

But that idea is far beyond people who make their living on unnecessary 

Instead, we'll have a completely broken system that will soon need more 
upgrades, YAY!

Eugen Leitl wrote on 3/11/2012 1:07 AM:
> ----- Forwarded message from William Herrin<bill at herrin.us>  -----
> From: William Herrin<bill at herrin.us>
> Date: Sat, 10 Mar 2012 18:11:09 -0500
> To: Sven Olaf Kamphuis<sven at cb3rob.net>
> Cc: "nanog at nanog.org"<nanog at nanog.org>
> Subject: Re: filtering /48 is going to be necessary
> On Sat, Mar 10, 2012 at 5:47 PM, Sven Olaf Kamphuis<sven at cb3rob.net>  wrote:
>> just get routers with enough memory...
>> i'm rather for a "specification" of a minimum supported route-size (let's
>> say something along the lines of 64GB in each border router, it's 2012 after
>> all ;) than for putting limits on the prefix sized announced so "old junk"
>> can still stay connected to the internet.
>> let's say, there is 6 billion people in the world.. if they all have 1 route
>> table entry (average ;) i see no technical limitations on anything produced
>> AFTER 2008 actually.
>> stop buying crap without sufficient ram, or just scrap it and get new stuff.
>> (which you're going to have to do to efficiently route ipv6 -anyway- at some
>> point, as your old stuff, simply doesn't even loadbalance trunked ethernet
>> ports properly (layer 3 based) ;)
> Sven,
> A) 7 billion people in the world, not 6.
> B) 7B IPv6 routes won't fit in a 64GB radix tree once, let alone the
> several times they'd need to in order to be useful in a router. For
> that matter, 6B routes won't fit either. (Hint: FIB plus at least one
> RIB for each peer)
> C) Big iron is either using massively parallel FIBs (many copies of
> the radix tree) or they're using TCAM instead of DRAM, a specialized
> tristate version of SRAM. In either case, you're talking 10 to 100
> times the cost, ten times the power consumption and ten times the heat
> versus DRAM.
> D) No computer presently exists on which the BGP protocol could keep
> up with today's update rate per prefix with 7B prefixes.
> A router handling 10M routes is achievable today if we're willing to
> go back to $20k as the minimum cost BGP box. That's an order of
> magnitude more than we have now and three orders of magnitude short of
> where we need to be before we can stop sweating the prefix count.
> Regards,
> Bill Herrin

Adam L. Beberg

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