That MIT paper

Thu Aug 12 20:36:35 UTC 2004

On Thu, Aug 12, 2004 at 01:35:36PM +0200, Niels Bakker scribed:
> 
> * dga at lcs.mit.edu (David G. Andersen) [Thu 12 Aug 2004, 02:55 CEST]:
> > Global impact is greatest when the resulting load changes are
> > concentrated in one place.  The most clear example of that is changes
> > that impact the root servers.  When a 1% increase in total traffic
> > is instead spread among hundreds of thousands of different, relatively
> > unloaded DNS servers, the impact on any one DNS server is minimal.
> > And since we're talking about a protocol that variously occupies less than
> > 3% of all Internet traffic, the packet count / byte count impact is
> > negligible (unless it's concentrated, as happens at root and
> > gtld servers).
> 
> This doesn't make sense to me.  You're saying here that a 1% increase in
> average traffic is a 1% average increase in traffic.  What's your point?
>
> if a load change is concentrated in one place how can the impact be
> global?

  Because that point could be "critical infrastructure" (to abuse
the buzzword).  If a 1% increase in DNS traffic is 100,000 requests
per second (this number is not indicative of anything, just an
illustration), that could represent an extra request per second per
nameserver -- or 7,000 more requests per second at the root.
One of these is pretty trivial, and the other could be
unpleasant.

> At root and gTLD servers I assume DNS traffic occupies significantly
> more than 3% of all traffic there.  Still, a 1% increase remains 1%.

   Sure, but the ratio still plays out.  If your total traffic due
to DNS is small, then even a large (percentage) increase in DNS traffic
doesn't affect your overall traffic volume, though it might hurt
your nameservers.  If you're a root server, doubling the DNS traffic
nearly doubles total traffic volume, so in addition to DNS-specific
issues, you'll also start looking at full pipes.

  -Dave

-- 
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