ndt-users list created

[Rich Carlson <>]

Larry;

A couple of months ago I found that tests were timing out and failing 
after the C2S test.  The problem turned out to be a bug in the applet 
code.  Specifically, Java uses blocking I/O calls and the client would 
enter a write state (I/O call), but the server closed the connection due 
to a timeout.  The result was that the client would hang, and the S2C 
test would fail.

This bug was fixed in v3.6.4.  The ANL and USCS servers both pre-date 
this version.  (Yes, I know the version numbers are higher, but that's 
another story).

One way to verify that 3.6.4 does fix this problem is to test against 
one of the measurementlab.org servers 
http://www.measurementlab.org/measurement-lab-tools#tool1

Rich

On 11/2/2010 5:13 AM, Larry Vaden wrote:
> Hello NDT-users,
>
> The test is performed against ndt.anl.gov:7123 and fails;  the test
> does not fail when performed against ndt.ucsc.edu:7123.
>
> Verizon dry DSL --- ActionTec GT704WGB dsl modem --- MikroTik RB750
> --- XP laptop
>
> The ActionTec obtains a public IP address from Verizon.
>
> The MikroTik diverts only RFC1918 space via L2TP tunnel to our network
> (texoma.net, ASN 4963).
>
> Everything seems to function OK (public address space, RFC1918 address
> space suffers ~ 2 msec latency).
>
> NDT takes ~ 2 min to complete the 10 second C2S test, then has
> problems with the S2C test.
>
> Double NATing is occurring.
>
> Is this likely a cockpit error on my part?
>
> THANKS for such a great tool --- we use it often to find problems in
> our rural wireless network.
>
> kind regards/ldv
>
> Larry Vaden, CoFounder
> Internet Texoma, Inc.
> Serving Rural Texomaland Since 1995
> We Care About Your Connection!
>
> ===== testing against ndt.internet2.edu
>
> TCP/Web100 Network Diagnostic Tool v5.5.4b
> click START to begin
>
> ** Starting test 1 of 1 **
> Connected to: ndt.anl.gov  --  Using IPv4 address
> Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
> checking for firewalls . . . . . . . . . . . . . . . . . . .  Done
> running 10s outbound test (client-to-server [C2S]) . . . . . 370.0kb/s
> running 10s inbound test (server-to-client [S2C]) . . . . . . Protocol error!
> S2C throughput test FAILED!
> Protocol error!
>
> click START to re-test
>
> ** Starting test 1 of 1 **
> Connected to: ndt.anl.gov  --  Using IPv4 address
> Another client is currently being served, your test will begin within
> 135 seconds
> Another client is currently being served, your test will begin within 90 
> seconds
> Another client is currently being served, your test will begin within 45 
> seconds
> Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
> checking for firewalls . . . . . . . . . . . . . . . . . . .  Done
> running 10s outbound test (client-to-server [C2S]) . . . . . 371.0kb/s
> Error in parsing tests results!
>
> click START to re-test
>
> ===== testing against ndt.ucsc.edu:7123
>
>
> TCP/Web100 Network Diagnostic Tool v5.5.4a
> click START to begin
>
> ** Starting test 1 of 1 **
> Connected to: ndt.ucsc.edu  --  Using IPv4 address
> Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
> checking for firewalls . . . . . . . . . . . . . . . . . . .  Done
> running 10s outbound test (client-to-server [C2S]) . . . . . 372.0kb/s
> running 10s inbound test (server-to-client [S2C]) . . . . . . 760.80kb/s
> Your PC is connected to a Cable/DSL modem
>   [S2C]: Packet queuing detected
>
> click START to re-test