tcp analysis tool?

Kevin Oberman oberman at
Fri Oct 19 10:22:47 PDT 2007

> Maksim Yevmenkin wrote:
> > On 10/18/07, Julian Elischer <julian at> wrote:
> >> does anyone have a favourite tool for analysing tcp flows to easily figure out why a transfer is slow?
> >>
> >> I am hoping for something that can help visualise the flow as one of those
> >> "two timeline poles with lines between them" diagrams..
> >>
> >> (that doesn't require too much extra software to be loaded.
> > 
> > i used tcptrace at one point.
> > 
> >
> > 
> > works on dumps produced by tcpdump and can do some plots and provides
> > some statistical data.
> > 
> > thanks,
> > max
> thanks..
> I see from the man page it can do what I want!

Both tcptrace and xplot (which is needed to display the graphs) are in

tcptrace does the best I have seen of reporting on what is happening
under the covers in a TCP transfer, but it does not exactly tell you why
performance is poor. It does the best job I have seen, but I still find
that I need to dump data into a spread-sheet and generate a plot to get
some data.

Figuring out why systems don't get good TCP performance is a very
difficult thing as there are so many things that can slow it down. We
have lots of GE or 10GE connected sites and only handful have any
clue about tuning for good TCP performance and many have other problems
that make end-system tuning inadequate to fix he problem.

If anyone figures out a better way to tell customers where the problem
is, let alone fixes it, would be a true hero! 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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