[e2e] number of flows per unit time in routers

[Detlef Bosau]

Ping Pan wrote:
> 
> Hi,
> 
> This is very interesting. Other than backbone links, does anyone have
> data on campus and carrier edge links? Have some flow duration
> information would be nice too.
> 
> Counting flows in the backbone is interesting, but the flows are mainly
> processed at edge. So it would be nice to see something in that region.
> 

I see the point. However, the problem is that in campus links
statistical methods are perhpas much more difficult to apply than in
backbone links.
In backbone links, I "tend to believe" (my apologies for the word, but
in fact TCP congestion control _has_ some aspects of a religion...) that
statistical abstraction is possible. I don´t believe this in campus
links.

However, from my own experience, on campus networks often routers are
equipped with "sufficient memory", i.e. congestion drop does hardly
occur, and than anything works fine. As long as the queues resulting
from that do not introduce inacceptable latencies, anything is fine.

So, although a study of network behaviour on campus networks may be
interesting, the question is: From what network size on this study
is really helpful and relevant? And in which cases networks are designed
by "feeling", "faith and religion", "well founded private opinions" - or
simply because the local BOFH-instance is big enough and old enough and
ugly enough to design a network and that´s it?

I think, this is an important question. I guess, that backbone traffic
is quite well understood today. Furthermore, I guess traffic
in small networks is not understood because there is nothing to
understand. You don´t need any networking expertise to provide
for a proper Linux installation party. The problem is the area in
between. When networks become that large that they _must_ be understood,
nevertheless
they are still that small that the statistical and asymptotic
abstraction from the Tier 1 Backbone do not hold.

This could be the case for networks with, just as a guess, say 5.000 to
100.000 participants. Just a guess. So, provider links and provider
networks
may be really interesting.

Detlef


-- 
Detlef Bosau
Galileistrasse 30
70565 Stuttgart
Mail: detlef.bosau at web.de
Web: http://www.detlef-bosau.de
Mobile: +49 172 681 9937