Re: Cascading Failures Could Crash the Global Internet

[<sgorman1 () gmu edu>]

I believe the comments about heterogenous networks has to do with a 
measurement called assortivitiy that is used in statistical mechanics.  
A homogenous network is when nodes connect preferentially to nodes like 
them.  In a heterogenous network they connect to nodes that are not 
like them.  For networks like the Intneret and the electric grid it is 
measured by the number of connections a node has.  

The kicker, that the author's are alluding to, is that the more 
heterogenous a network is the more vulnerable it is to targeted 
attack.  By taking out a highly connected node - lots of poorly 
connected nodes that use it as a hub are lost.  The AS network had the 
highest heterogenous score of real-world tested networks, so lots of 
folks on that bandwagon.  

That said I don't think the tolerance parameter they set up in the 
paper makes much sense when applied to the Internet at the AS level.  
Basically it says once traffic exceeds a certain threshold the node 
will fail and cause cascades across the network.  You guys are the 
experts but that does not sound overly realistic.
----- Original Message -----
From: Douglas Denault <doug () safeport com>
Date: Saturday, February 8, 2003 7:31 am
Subject: Re: Cascading Failures Could Crash the Global Internet

> The model proposed makes several assumptions. My question is about:
>
>   Many real-world networks are heterogeneous and as such are 
> expected to
>   undergo large-scale cascades if some vital nodes are attacked.
>
> on page 3. I do not get the basis for this assumption. So any help 
> for a 60's
> educated math major would be appreciated.
>
>
> On Thu, 6 Feb 2003 sgorman1 () gmu edu wrote:
>
> > The paper is avaibable on the Los Alamos site free of charge:
> >
> > http://xxx.lanl.gov/PS_cache/cond-mat/pdf/0301/0301086.pdf
> >
> >
> >
> > ----- Original Message -----
> > From: Sean Donelan <sean () donelan com>
> > Date: Thursday, February 6, 2003 12:43 pm
> > Subject: Cascading Failures Could Crash the Global Internet
> >
> > > Sigh, there are differences between tightly coupled networks, 
> such as
> > > the electric power grid and loosely couple networks like the 
> > Internet.
> > > But there are also some similarities, such as electric grids 
> use DC
> > > interconnections to limit how far AC disturbances propagate; the
> > > Internet uses AS interconnections to limit IGP disturbances from
> > > propagating.
> > >
> > > http://sci.newsfactor.com/perl/story/20686.html
> > >
> > > The actual article requires payment to read
> > > http://ojps.aip.org/getabs/servlet/GetabsServlet?
> > prog=normal&id=PLEEE8000066000006065102000001&idtype=cvips&gifs=Yes
> > >
>
> _____
> Douglas Denault
> doug () safeport com
> Voice: 301-469-8766
>  Fax: 301-469-0601