Re: Network integrity and non-random removal of nodes

[<sgorman1 () gmu edu>]

Hmm - not sure on who owns the trees, but if anyone does know it would
be very useful.  Most of the work I've read say the connection
distribution follows a power law, and is why I did not think it would
follow a linear pattern, but just guess work on my part.  There has been
some work at BU that says all the power law stuff is just sampling bias
inherent in traceroute type of data aquisition.  In which case
vulnerbility might not be as dire as some of the early reports.  How to
get an accurate topology is the real big problem, but no need to reopen
the private sector vs government vs academia debate.  

----- Original Message -----
From: William Waites <ww () styx org>
Date: Thursday, November 21, 2002 7:56 pm
Subject: Re: Network integrity and non-random removal of nodes

> > > > "Sean" ==   <sgorman1 () gmu edu> writes:
>
>    >> The supposition  would be that  the remaining nodes  are evenly
>    >> distributed around the core  so the percentage of nodes outside
>    >> of the core without connectivity  should be roughly the 
> same as
>    >> the percentage of nodes removed  from the core.  At least until
>    >> the core goes non-linear...
>
>    Sean> Is that the supposition stated in the paper? 
>
> No.
>
>    Sean> The  reason being  it  contradicts quite  a  bit of  similar
>    Sean> research.   Nodes inside  and  outside of  the  core do  not
>    Sean> typically  disconnect at the  same rate.   
>
> References? Note  that I posited  that the rate was  proportional, not
> the same.
>
>    Sean> The nodes  outside of  the core on  the other hand  are much
>    Sean> more sparsely connected.  55% of them are trees meaning that
>    Sean> they only have one connection.  There is no back up 
> link, so
>    Sean> if their big hub node goes down they are out of commission.
>
> That's more or less what I  said.  If the trees are evenly distributed
> around the core, and  you take away 2% of the core,  you can 
> expect 2%
> of the  trees to disappear too.  Of course 2%  of the trees is  a much
> larger number of nodes than 2% of the core.
>
>    Sean> Hence you could have large numbers of nodes outside the core
>    Sean> disconencted  before you  would  see any  effect inside  the
>    Sean> core.  By the time the core goes non-linear the 
> periphery is
>    Sean> gonna be long gone and disconnected.
>
> True iff the links to  the periphery are not evenly distributed across
> the  core, which is  my, perhaps  faulty, underlying  assumption. Does
> UUNet still own most of the trees?
>
> -w