North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

How many nexuses would it take?

  • From: Sean Donelan
  • Date: Fri Jul 28 07:51:57 2000

I took a stab at estimating what it would take to knock out the
top 4% of ASNs on the Internet, thus meeting Tu's threshold for
partitioning the net.  Of course, to really determine this requires
perfect knowledge, and at least some NDA information from the
providers involved.

My rough estimate is 60 different physical locations worldwide would
need to be destroyed.  But I suspect congestive collapse would occur
after 20 different physical locations were destroyed.  This assumes
you went after the nexus(es?) of the Net.  You could possibly isolate
the requisite nexuses, without destroying them. But knowing those
locations requires a level of knowledge about the physical overlap
between providers I don't have.

I think there is a substantial physical overlap between providers' right
of ways, so I wouldn't be suprised if the same level of effort to destroy
the connectivity of the top 4% of the providers damaged the top 25% (SWAG)
since many of the 'tier 2,' and even 'tier 3' providers co-locate in
the same physical locations as the top 4%.  But I have no proof, only
a educated guess.

>From the studies I know about, disrupting national telephone service
would require less effort.  A logical attack on the net would require
substitutionally less effort.

This also assumes a static network.  Network operators could substantially
increase the number of peering locations and ASN interconnectivity in
response.  Those shadow connections and locations I spoke about.  Unlike
telephone switches, backbone routers are very fungible.  So its not
inconceivable, some new connectivity between ASNs would rapidly appear in
places where there wasn't any before.

A lot of Tier 2 and Tier 3 providers are multi-homed, but don't currently
provide transit between backbones.  This is an administrative policy, not
a physical restriction.  It is possible for substantial additional inter-ASN
connectivity to be brought up very quickly, assuming you had enough remaining
communications to coordinate it.

Is the shadow connectivity of tier 2 and tier 3 providers enough to invalidate
the theory the Internet as a scale-free network?   I don't know.

On Wed, 26 July 2000, Dave Crocker wrote:
> The proffered theory is that a small number of nexus points that form an 
> essential core.  Take out that small number and the remaining alternate 
> paths won't be sufficient.
> 
> 25 is probably a large number, never mind one or two orders of magnitude more.
> 
> Some effort at figuring out how many (and which) would have to be 
> simultaneously removed strikes me as a worthy exercise, to make sure that 
> the number is high (and the specific sights are well enough protected.)
> 
> Perhaps it's already been done and the results kept quiet.  That's fine.
> 
> As long as the fragility is nowhere near as extreme as the article implies.