Subject: Grazing the commons

From: [email-masked]
Date: Wed, 8 Aug 2001 13:09:06 -0700 (PDT)

In Randy Bush's presentation at the plenary, he refers to the
multi-homing customer "grazing the commons" by having a long prefix
route carried into the default free zone and thus consuming resources
in routers in lots of networks which are not paid for that work.

It's a powerful metaphor, but flawed.  If we are honest with
ourselves, we have to acknowledge that we put those sheep in that
meadow.  

"New" ISPs have sold multihoming to customers as a way to gain market
share against incumbents whenever they could, and as is often the
case, the customers learned the lesson well.  They realized that the
only way they can control their own routing policy right now is to
have networks announced in a way that lets them prepend, use
communities, agreed on MEDs and generally have the termerity to act
like they really run a network.  As ISPs have had troubles, the
customers continue to have the message that they need to multihome
reinforced not just by sales folk meeting quotas but by mass media and
less technical folk giving their "Film at a Eleven"

Multihoming does present a real problem to routing table growth, don't
get me wrong.  But let's not expect to be able to engineer solutions
which take away customer's ability to achieve what they believe
multihoming gets them.  Not only won't the customers be happy, but
there might even be ISPs who want revenue enough to keep doing it.  We
have to engineer solutions which keep that ability while allowing the
DFZ to survive the process.  As Randy noted, ptomaine is the WG
working on the problem, and I won't belabor the potential solutions
here, but I think we have to start the work acknowleging that we have
met the enemy, and he is us.

			regards,
				Ted

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From: Randy Bush <[email-masked]>
Date: Wed, 08 Aug 2001 21:25:29 +0100

> share against incumbents whenever they could

yup.  and they get the money.  but, since they neglected to put paying
the rest of us in the financial model, i presume they will excuse our
not spending our critical resources to aid their income.

life can be simple.

randy

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From: [email-masked]
Date: Thu, 9 Aug 2001 01:06:22 -0700 (PDT)

> not spending our critical resources to aid their income.

Pithy, but not salient.  "They" don't pay "us" to carry a new route
when "they" persuade Bob's Bait shop to join the 'net either; they
pay "us" (transit) or barter with "us" (peering) to carry the traffic,
not the route.  The route just enables "us" to get our slice of
the traffic pie.

The main point, though, remains that multi-homing customers do so to
achieve certain goals; they have, in essence made an investment to
that end and attempts to frustrate their desire to achieve those goals
will result in a much more prolonged game of whack a mole than we
really need.  Sure we can shift the filter boundary; if that is all we
do, people will just start wasting address space in order to achieve
their goals.  If we engineer a solution that enables them to achieve
their goals without blowing up the routing table the next five years
will pass a lot quicker.

			regards,
				Ted

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From: Pekka Savola <[email-masked]>
Date: Thu, 9 Aug 2001 17:18:33 +0300 (EEST)

> not spending our critical resources to aid their income.

One note about about "plain and simple" filtering of /24 and more
specifics in the presentation.. IPv4 Anycast address prefixes are assigned
as /24's and in practise can't be advertised as less specific ones.

Not that anyone is using them anyway, but for example ngtrans has 6to4
anycast relay router prefix defined, and shipworm on the way.  DNS over
anycast is being  practised AFAIR.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords