Keynote/Boardwatch Internet Backbone Index A better test!!!

Tue Jul 1 15:55:54 UTC 1997

lhoward at UU.NET writes:

> 1.  Although a variety of backbones is used, the study does not say
> which ones.  Also, even though the study does point out the assymetrical
> routing of a web transavtion (hot-potato), it doesn't point out that the
> traffic being measured is a brief web request (which is dumped to the
> web server's backbone ASAP) answered by a long response (10KB in this
> case, dumped to the querier's backbone).

Ironically, the only person I can remember actively (and
publically) questioning the wisdom of hot potato routing
for several applications is Curtis Villamizar.  While Tony
Bates and I had what seemed to be good reasons for doing
closest-exit routing (among other routing policies) at the
time, and there are strong economic incentives for
maintaining closest-exit routing among peers, there are
certainly drawbacks.

Considering that the Keynote/Boardwatch study purports to
help content-providers decide where to locate their
content, poor performance attributable to closest-exit
routing should have engineers considering the wisdom of
that particular routing policy with respect to that
particular market segment, depending on the focus of their
businesses.

The nice thing about the Keynote test is that it might get
some of the cleverer people around here thinking of the
Internet in a more abstract way than they might be used to.

When I think in a more end-to-end fashion about comment #1
above, it seems that a provider who is rated poorly
deserves the rating, even though the performance problem
may be attributable to a peer's network's congested lines,
broken equipment, or whatever.  In effect, by taking an
end-to-end approach, this test also rates networks'
routing policies.  If the routing policy drives traffic
through a competitor's suboptimal path, and this degrades
end-to-end performance, then the provider with that
routing policy will receive a poorer rating than otherwise.

One of the things that should be thought about is that
there may be ways to improve end-to-end goodput by
changing one's own network based on what one can infer
from tests similar to the Keynote ones (or indeed similar
to Vern Paxson's tests), as much as what one can infer
from what one's own equipment is doing or seeing.

> All of the previous notwithstanding, I would be interested in a better
> version of this study.  Even more interesting would be to track how
> providers do over the course of several studies--who responds well to
> backbone congestion?

Personally, I would take this comment as a sign that the
study and its publication is astoundingly successful.

Finally, I would rather see people respond to congestion
in a cleverer fashion, i.e. by deploying or pressing for
the deployment of better WWW transport technology.  There
are some people with very clever ideas about caching and
lazy proxies, and some clever ideas about changing HTTP in
dramatic ways, that deserve some attention, as these ideas
are more likely to help people and information meet more
quickly in the long run than any amount of tweaking the
underlying transport fabric ever will.

	Sean.