ndt-users list created

[Richard Carlson <>]

Hi Edson;

The short answer is:

that this message indicates that the old (original) algorithm for detecting an Ethernet duplex mismatch was triggered.  If the client is attached to a FastEthernet (100 Mbps) LAN then this duplex mismatch condition may exist.  More than likely it is a false positive and you should be looking for other problems.

The longer answer is:

The NDT server uses a collection of web100 variables to look for specific problems with a clients network connection and its configuration settings.  In the mid 90's there were a lot of problems with Ethernet duplex mismatch conditions, in this condition the PC and Ethernet switch don't agree on the duplex settings for the link and this causes poor performance in 1 direction and abysmal performance in the other direction.  After running a series of experiments I defined a set of conditions that would be true if a duplex mismatch condition existed in a FastEthernet LAN.  Basically this test was true if the server was resending a large number of packets and the throughput was asymmetric.  

Unfortunately this same condition is true for some networks that just have a high loss value and or asymmetric throughput (things like wireless LANs and cable/dsl connected clients).  This lead to an effort to improve this detection algorithm.  While our research showed a better detection algorithm, this new algorithm has not found it's way in to the production code for non-technical reasons.  I hope that one day soon a new detection algorithm can be released.  Stay tuned.

Regards;

Rich

On Jun 29, 2009, at 11:57 AM, Edson Rodriguez wrote:

Hello,
Does anyone know what the following warning means?:

"old duplex mismatch condition detected"

What throws me off is the "Old" part, since I have seen the  "duplex mismatch condition exists" before, which is different.

 

Please let me know.

Edson

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Edson Rodriguez
K-20 NSS - Regional Data ITU
NW Educational Service District
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Richard Carlson

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