ndt-users list created

[Richard Carlson <>]

Hi Martyn;

Comments in-line
At 03:11 PM 10/27/2005, chet wrote:
> Is there an analyser I can use to read the results displayed by ndt, I'm 
> getting weird results when running tests under different environments, 
> back-to-back tests produce results similar to: -
>
> client to server 84.86Mb/s
> server to client 62.86Mb/s

Different results for different clients or after moving a client to a new 
location are to be expected.  That's one of the reasons I started this 
project, I couldn't easily document all these changes.

> I'm guessing I have got to do the /etc/sysctl.conf edit to resolve the 
> above issues but need to ask first
>
> If I put a HUB in the way then these results drop by around 20Mb/s, these 
> are not the exact results as I'm not in the office now

The HUB is a shared device, so the hosts will drop to half-duplex.  Half 
duplex connections will run at 60 - 70 % of the link capacity.  This is due 
to the Ethernet CDMA-CA protocol and should be expected.  (I'll note here 
that the half/full detection algorithm probably doesn't work right now so 
you'll get a report that the path is full duplex).

> My set up for back-to back results are both server and PC set to 100 half 
> duplex, server has twin p3 500 with 512 meg of ram, my laptop is a Pentium 
> p4 with 256 MB of ram
>
> If I go across a VLAN the Cat 5509 has it ports set to 100 half duplex and 
> the Cat 2900 is set to 100 half duplex, if I set them all to 100 full 
> duplex I get the following: -
>
> Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
> running 10s outbound test (client to server) . . . . . Server busy: Please 
> wait 30 seconds for previous test to finish

This indicates that the client can't reach the server.  Check the IPTABLES 
to ensure that hosts on this VLAN can access the server.  Or check for 
other firewalls that are blocking port 3002 (3003 is getting through 
because the middlebox test is working).  Also see below for some debugging 
steps.

> What is the optimum set up for server, is it 100 half duplex

I'd suggest connecting the server directly to a switch and running it in 
full-duplex mode.  This will prevent the NDT server link from becoming a 
bottleneck, making it easier to debug other problems.

> What is new in 3.1.4b as I'm using 4a, if I update to 4b I guess I leave 
> 4a where it is and just start ndt from 4b

version 3.1.4b simply adds in the appropriate shutdown() commands into the 
server to prevent multiple clients from interfering with each other.  If 
you have patched the web100srv.c file by hand, you do not need to 
download/install the 4b version.

Lastly, the NDT server supports a wide variety of debugging and analysis 
functions.  Most of them are enabled by command line options.  The 
interesting ones are:

        -t  This option causes the NDT server to write a tcpdump file for 
every
            test.  These files can be viewed via the tcpdump program or 
you can]
            create graphical plots using the tcptrace program.  (search 
the web if
            you want more details on these programs).  One simple debugging
            task is to run the web100srv process with the -t option and 
verify that
            2 -non zero length ndttrace-ip.addr.port.number files are 
created.  This
            indicates that the test ran and some data was collected.

        -x  This option causes the NDT server to run any experimental 
code.  At
            the present time the this will cause the server to write a Web100
            snap-log file for each server-to-client test.  You can then 
use the
            Web100 watchsender program to view the collected data.  Not much
            you can do with this, but it is available

        -d  This option turns on debugging.  The more -d flags you specify 
the
            more debugging details you get.  Messages are written to the 
stderr
             interface so you need to redirect them to a file or run the 
web100srv
             process in the foreground.

        Finally, there is a small program /usr/local/bin/analysis that 
parses the
        web100srv.log file and writes out a bunch of details.  You may 
find this
        useful or not.

Regards;
Rich
Rich

> Is there a analyser that I can use to manipulate the results
>
> Thanks
>
> Martyn

------------------------------------



Richard A. Carlson                              e-mail: 

Network Engineer                                phone:  (734) 352-7043
Internet2                                       fax:    (734) 913-4255
1000 Oakbrook Dr; Suite 300
Ann Arbor,  MI  48104