The Computing and Instrumentation Solutions (CIS) Division has developed a Network Diagnostic Tool (NDT) to help diagnose network performance and configuration problems. This tool can determine the speed (Dial-up to OC-192) and duplex (full or half) settings of your slowest link on the end-to-end path between a desktop client computer and a server running the NDT. It can determine if your performance is being limited by network congestion (e.g., competing traffic over the shared portions of the end-to-end path). It can also determine if the throughput is limited by the client's network configuration parameters. Finally, the tool looks for, and reports, two serious error conditions, duplex mismatch and faulty hardware.

The NDT distribution (web100-tools.tar) contains the programs and instructions needed to deploy an NDT server on your network or home institution.

Publicly accessible NDT servers are located at various points on the global Internet. The main HTML page contains links to these public servers. Please contact Rich Carlson racarlson@anl.gov to modify this list. There servers are provided as a service to the Internet community and this list may change as new servers are installed and old servers are decommissioned.

Argonne National Laboratory - Chicago IL (USA)
Swiss Education and Research Network (Switzerland)
University of Michigan - Flint MI (USA)
University of California - Santa Cruz (USA)

As noted above the tool will analyze the entire end-to-end path between the desktop client computer and the NDT server. The results are organized into three levels, allowing you to drill down to the level that you or your system administrator needs to identify the configuration problems. In addition, an email button is provided to make it easy to report problems to the local administrator. The user may also manually cut and pasting the results into an email if the automatic method fails. The ANL NDT may contain new functions or features under development.

Levels of Results Reported

Level 1 - Main Page The main page reports the high level results of each test. These results include the measured throughput to and from your desktop client computer, a summary of the kind of link you have (Dial-up to OC-192), if other traffic is using a shared network link(s), or if serious problems exist. This one sentence overview is intended to provide the user with a concise picture of the state of the network (i.e., something is seriously wrong or everything is working properly).

Level 2 - Statistics By clicking the "Statistics" button you will learn what is limiting the throughput and what, if anything, can be done to improve performance. The summary information on the Main Page is expanded here to show the results of the five configuration tests. This is followed by an analysis of what is limiting the throughput of this test. Throughput may be limited due to your desktop computer's configuration, the NDT server's configuration, or the network path connecting these two computers. The percentage of time spent in each state (i.e., receiver limited, sender limited, or network limited) is given. Suggestions for improving throughput may also be given. Lastly, the results of the several TCP performance enhancement options are reported. The NDT reports the results enhancement negotiation between the client and server (i.e., what enhancements are being used), unlike other tools which report what enhancements could be used.

Level 3 - More Details By clicking the "More Details" button you will see the detailed parameters and values that were used to perform this analysis. Near the bottom of this page you will find the detailed conditional tests that were used to analyze the five configuration tests. You will also find the theoretical network limits for this connection. These limits can help identify the major throughput limiting factors.

Email Results By clicking the "Report Trouble" button you will automatically generate an email message that can be sent to your network and/or system administrator. The NDT administrator can configure the proper email addresses for your site. This simplifies the steps a user needs to take to report a problem and ensures that the administrator received sufficient information to aid in troubleshooting the reported problem.

For more information and details on bringing up your own server contact Rich Carlson Email: RCarlson@internet2.edu Phone: (734) 352-7043