ndt-users list created

[Richard Carlson <>]

Hi Ken;

Thanks for the enquiry.  At the present time I don't know of anyone 
working on a parallel flow module.

The NDT system was designed to look for a very specific set of known 
problems that impacted performance.  The idea is that the campus NOC 
runs a local server and when the phone call comes in saying "what's 
wrong with the network?" the NOC staff gives the caller the NDT URL 
and says, "please run this test and we'll look at the results".  This 
lets the community get real data on possible problems and we can get 
past the finger pointing stage we usually get stuck in.

Thus the NDT was not designed as a generic test infrastructure or as 
a replacement for something like Iperf.  However, we have had some 
interest in expanding the NDT system to support more functions.  For 
example the folks at NCMC extended the system to allow the client to 
automatically repeat tests so they could monitor multiple links 
without having to install HW/SW at remote sites.  Once this code was 
working they shared the mods with us and we incorporated that 
functionally into the current distribution.  It's a sysadmin option 
that can be enabled by adding some PARAM options into the NDT web page.

Right now I have no plans to implement parallel TCP streams, and 
would point someone to BWCTL for this function.  However, I would 
have no objection to your checking into how to modify the NDT source 
code if you want/need this functionality.  All I ask is that you send 
me the patches that I can put into the NDT contrib directory or 
incorporate into the main NDT distribution.

Regards;
Rich
NDT developer

At 05:44 AM 4/17/2008, Webb, Ken wrote:
> Hi,
>
> I was wondering whether anyone has tried to adapt the NDT client to run
> parallel TCP sessions. The server I believe should already handle this,
> although I would still like to be able to limit the server to one client
> host at a time.
>
> In our test environment I'm seeing the sort of 'random' packet loss
> which seems to favour multiple parallel flows (with small window size)
> over single flows. As I'm interested in periodically measuring the
> effective size of the pipe available I'd like to adapt the client to run
> multiple sessions. Has anyone tried or does it run contrary to the
> philosophy and design of NDT?
>
> Ken Webb,
> UPC Broadband,
> Boeing Avenue 53,
> 1119PE Schiphol Rijk,
> The Netherlands.

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Richard A. Carlson                              e-mail: 

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