[arin-ppml] Policy Proposal: A Modest Proposal for an Alternate IPv6 Allocation Process

William Herrin bill at herrin.us
Fri Jun 5 16:04:02 EDT 2009

On Fri, Jun 5, 2009 at 2:06 PM, Ted Mittelstaedt<tedm at ipinc.net> wrote:
> Today I can walk into the discount store and by a brand new PC with 2GB of
> ram for under $350.  Yet, Cisco and Juniper are still including as
> standard ram amounts, miserable, paltry amounts far smaller than that.
> My gut feeling here is that the router vendors could EASILY and CHEAPLY
> and QUICKLY greatly expand the capacity of their products IF demand called
> for it - thus removing the need for filtering.
> Is this an accurate assessment?  Or is there really some reason that a
> router cannot be built with more ram than a half gig?

Hi Ted,

Without going into great technical detail, building a router that
handles 10M routes is less like building a PC with 8 gigs of DRAM and
more like building a PC with an 8 gig CPU cache.

You can buy a Cisco 2800 series router with 1 gig of DRAM that will
happily handle north of 2M BGP routes. As long as your traffic is in
the sub-100mbps range and you don't mind waiting 10 minutes for it to
process the BGP table changes after a nearby link failure.

This will work because at the lower routing speeds I can afford to
wait for multiple CPU cache fills as the processor wanders down the
log-n FIB trie to find the correct next hop for the destination

At gigabit plus speeds, I either have to parallelize that so that I'm
doing dozens of lookups on dozens of CPUs and dozens of parallel banks
of DRAM, or else I have to stuff the FIB entries in a very expensive
TCAM instead of using DRAM.

If you're interested in the technical detail, the best article I've
found about TCAMs is: http://www.pagiamtzis.com/cam/camintro.html

On Fri, Jun 5, 2009 at 2:26 PM, Eliot Lear<lear at cisco.com> wrote:
> Any policy that requires additional renumber will encourage use of
> ULAs tied to NAT.  It is already difficult to argue against those
> who want to insulate themselves from renumbering events with
> ULAs. This policy would be the nail
> in the coffin for those of us who like globally unique and routed addresses.

Hi Eliot,

For better or for worse, I suspect that's a done deal. The Enterprise
Security folks like NAT because it fails closed. They'll use it quite
regardless of how the renumbering issue plays out.

Bill Herrin

William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004

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