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Re: Cascading Failures Could Crash the Global Internet
From: "Jack Bates" <jbates () brightok net>
Date: Fri, 7 Feb 2003 07:53:50 -0600

N. Richard Solis wrote:

Yeah yeah yeah.  I know that everything isn't simple.  I actually worked at a power plant so
none of this is new to me.  Can cascading failures occur?  Yes.  Witness the Great Blackout in
NYC.  My point was that there are places where the electrical network is designed to "blow the
bolts" to TRY and protect everything.  Does it work?  Most of the time, yes.  All of the time?
NO.

Bringing this back to topic. What you are refering to is similar to a failure within an AS. When you start having 
problems within one section of your network that could jeapordize the rest of your network, you cut it off until the 
problem can be fixed. Does it work? Most of the time, yes. All the time? No. Sometimes the failure is too rapid to 
avoid the cascade failure within the AS. This practice is seprate from grid and AS interconnects.

It is a complicated problem but you'd be suprised at how fast things can happen when you
HAVE to keep the system running.  There is a tremendous amount of skill concentrated in that
field and they do a good job of keeping everything running well.  How many turbine overspeed
events do <snip>

I agree. The same can be said for many networks. The difference is that dealing with some networking problems is new to 
many engineers. Without proper training and expecting a cascade failure, how do you know the fastest method to deal 
with it? I've had lots of practice on my network. I have an average stabalization rate of about 5 minutes now, but 
then, I redesigned my network a long time ago to effectively deal with such problems in a shorter time span.

The loss of a single transmission line isn't going to cause a whole station to trip.  If you're losing a
bunch though, you've probably got lots of other problems to worry about.

Also true with many networks today. However, this topic falls within a single grid. The original analogy was dealing 
with grid interconnects which have different requirements and must be protected at all costs. IF, and I don't think 
it's happened in a very long time, an entire grid lost integrity, it would be unacceptable for the grid to cascade into 
the other two grids. Extra percautions are put into place. In the same reguards, many Autonomous Systems do have 
different policies reguarding their interconnects compared to their internal network.

-Jack





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