Re: [Codel] [Bloat] Network test tools for many parallel/concurrent connections?

[Dave Taht <dave.taht@gmail.com>]

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On May 14, 2013 12:21 PM, "Stephen Hemminger" <stephen@networkplumber.org>
wrote:
>
> On Tue, 14 May 2013 15:48:38 +0200
> Jesper Dangaard Brouer <jbrouer@redhat.com> wrote:
>
> >
> > (I'm testing fq_codel and codel)
> >
> > I need a test tool that can start many TCP streams (>1024).
> > During/after the testrun I want to know if the connections got a fair
> > share of the bandwidth.
> >
> > Can anyone recomment tools for this?
> >
> > After the test I would also like to, "deep-dive" analyse one of the TCP
> > streams to see how the congestion window, outstanding-win/data is
> > behaving.  Back in 2005 I used-to-use a tool  called
> > "tcptrace" (http://www.tcptrace.org).
> > Have any better tools surfaced?
> >
>
>
> You may want to look at some of the "realistic" load tools since
> in real life not all flows are 100% of bandwidth and long lived.

You may want to look at some realistic load tools since in real life
99.9Xx% of all flows are 100% of bandwidth AND long lived.

At various small timescales a flow or flows can be 100% of bandwidth.

But it still takes one full rate flow to mess up your whole day.

This is why I suggested ab.

Here bandwidth is an average usually taken over a second and often much
more. If you sample at a higher resolution, like a ms, you are either at
capacity or empty.

Another way of thinking about it is for example, mrtg takes samples every
30 seconds and the most detailed presentation of that data it gives you is
on a 5 minute interval. The biggest fq codel site I have almost never shows
a 5 minute average over 60% of capacity, but I know full well that Netflix
users are clobbering things on a 10 sec interval and that there are
frequent peaks where it is running at capacity for a few seconds at a time
from looking at the data on a much finer interval and the fq codel drop
statistics.

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