[73101] in North American Network Operators' Group
Re: That MIT paper
daemon@ATHENA.MIT.EDU (David G. Andersen)
Thu Aug 12 16:37:13 2004
Date: Thu, 12 Aug 2004 16:36:35 -0400
From: "David G. Andersen" <dga@lcs.mit.edu>
To: nanog@merit.edu, "David G. Andersen" <dga@lcs.mit.edu>
Mail-Followup-To: "David G. Andersen" <dga@lcs.mit.edu>,
nanog@merit.edu
In-Reply-To: <20040812113536.GD74928@snowcrash.tpb.net>
Errors-To: owner-nanog-outgoing@merit.edu
On Thu, Aug 12, 2004 at 01:35:36PM +0200, Niels Bakker scribed:
>
> * dga@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
--
work: dga@lcs.mit.edu me: dga@pobox.com
MIT Laboratory for Computer Science http://www.angio.net/
