nanog mailing list archives

Re: Shim6, was: Re: filtering /48 is going to be necessary


From: Ryan Malayter <malayter () gmail com>
Date: Tue, 13 Mar 2012 04:49:39 -0700 (PDT)



On Mar 13, 2:21 am, Masataka Ohta <mo... () necom830 hpcl titech ac jp>
wrote:
William Herrin wrote:
When I ran the numbers a few years ago, a route had a global cost
impact in the neighborhood of $8000/year. It's tough to make a case
that folks who need multihoming's reliability can't afford to put that
much into the system.

The cost for bloated DFZ routing table is not so small and is
paid by all the players, including those who use DFZ but do
not multihome.

Hi,

http://bill.herrin.us/network/bgpcost.html

If you believe there's an error in my methodology, feel free to take
issue with it.

Your estimate on the number of routers in DFZ:

        somewhere between 120,000 and 180,000 with the consensus
        number near 150,000

is a result of high cost of routers and is inappropriate to
estimate global cost of a routing table entry.

Because DFZ capable routers are so expensive, the actual
number of routers is so limited.

If the number of routes in DFZ is, say, 100, many routers and
hosts will be default free

For quite some time, a sub-$2000 PC running Linux/BSD has been able to
cope with DFZ table sizes and handle enough packets per second to
saturate two or more if the prevalent LAN interfaces of the day.

The reason current routers in the core are so expensive is because of
the 40 gigabit interfaces, custom ASICs to handle billions of PPS,
esoteric features, and lack of competition.

The fact that long-haul fiber is very expensive to run limits the
number of DFZ routers more than anything else. Why not take a default
route and simplify life when you're at the end of a single coax link?
If your lucky enough to have access to fiber from multiple providers,
the cost of a router which can handle a full table is not a major
concern compared with your monthly recurring charges.

--
RPM



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