[60757] in North American Network Operators' Group
Re: East Coast outage?
daemon@ATHENA.MIT.EDU (sgorman1@gmu.edu)
Fri Aug 15 14:37:16 2003
Date: Fri, 15 Aug 2003 14:30:31 -0400
From: sgorman1@gmu.edu
To: Iljitsch van Beijnum <iljitsch@muada.com>
Cc: Michael.Dillon@radianz.com, nanog@merit.edu
Errors-To: owner-nanog-outgoing@merit.edu
I think the power grid outage is a good example of the robust yet fra=
gile phenomenon found in many complex networks. The power grid is ro=
bust to even large variations in demand, but is extremely sensitive t=
o the loss of particualr power lines or generators (see any of the wo=
rk done by Massoud Amin). The reason is that vast majority of genera=
tors have only a few internconnections but there are a minority that =
have a large number that are critical to keeping the system going. I=
f one of those gerneators in the minority has a failure it can rapidl=
y result in a cascading failure since most of the adjacent generators=
do not have the capacity to handle the rerouted power. The Internet =
at the AS level is similar to the US power grid from a structural con=
nectivity perspective, except there is even a smaller minority of nod=
es with an even larger percentage of connections. Theoretically goin=
g from a few large transit providers to more mid size or smaller prov=
iders would increase the resilie...
The big 1996 power failure out west ended up resulting from a power l=
ine in Oregon that was downed by a falling tree branch. The rerouted=
capacity resulted in a cascading failure that spread to Denver and C=
alifornia.
----- Original Message -----
=46rom: Iljitsch van Beijnum <iljitsch@muada.com>
Date: Friday, August 15, 2003 1:53 pm
Subject: Re: East Coast outage?
>=20
> On vrijdag, aug 15, 2003, at 17:55 Europe/Amsterdam,=20
> Michael.Dillon@radianz.com wrote:
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> >> Perhaps the lesson to learn is that very large networks don't=
=20
> always>> lead to very high stability. A much larger number of=20
> smaller, more
> >> autonomous generation and transmission facilities might have=
=20
> much more
> >> reasonable interconnection requirements, and hence less wide-
> ranging>> failure modes.
>=20
> > And if we extrapolate that lesson to IP networks it implies that =
any
> > medium to large sized organization should do their own BGP peerin=
g
> > and multihome to 3 or more upstream network providers.
>=20
> While this certainly has its advantages, I don't think it follows=
=20
> from=20
> Joe's remarks. What would follow is having many smaller transit=
=20
> networks rather than a few big ones. But I think in this regard IP=
=20
> is=20
> well ahead of the electricity people.
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> Still, I don't think it's this simple, as the problem with power=
=20
> is=20
> that supply and demand must be the same at all times. So if a=20
> decent=20
> chunk of the network that connects the two goes down, the supply=
=20
> side=20
> gets into trouble because they're suddenly generating too much. If=
=20
> the=20
> difference is big enough it's probably impossible to arrive at a=
=20
> new=20
> equilibrium above 0 fast enough. If you connect everything=20
> together you=20
> can absorb bigger imbalances but then when you get one you can't=
=20
> absorb, the impact is larger of course.
>=20
> Fortunately in our business we have queues to smooth the spikes in=
=20
> network use and when we drop packets there are no sparks.
>=20
> > Perhaps we should start working on a hierarchical routing system =
in
> > which the concept of a "global routing table" cannot develop.=
=20
> Perhaps> announcements and withdraws should have a TTL so that=20
> they never
> > propogate very far from their source AS?
>=20
> Have a look at the work going on in the IETF multihoming in IPv6=
=20
> (multi6) working group and the IRTF routing working group.
>=20
>=20
>=20
