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Traffic Matrix Solver Troubleshooting

If the WorstLinkDiff is high, e.g., over 10%, you should analyze the Links tab. Sort on the Diff Util % Column to see the links with the worst link diffs. You can select the rows for these links and click the Highlight button to highlight the links on the map, and to check for reasons why the difference is high.

If “Measured Traffic” (actual load) on a link is extremely high but the traffic matrix tool places 0 traffic on that link (Model Traffic), this may be an indication of a routing scenario that needs to be resolved before proceeding. That is, you need to determine why the system is not routing any flow across that link. There are numerous possible reasons, and it varies from network to network. For example, there may be too many parallel links in part of the network, but the ECMP value is set too low.

The typical way to troubleshoot is by using the “P” Path button on the Map window, or via Network > Path & Capacity > Path, selecting two points, and analyzing the source of the bottleneck.

In some cases, you may have supplied an inaccurate set of sources and sinks. That is, the sources and sinks you specified for the traffic matrix flows does not match the locations where traffic is present, as indicated by your interface traffic file. Please consider adding a larger mesh of demands.

There can also be problems if the interface traffic data that you supplied is unknown or “0” on the vast majority of interfaces and the test demands are placed on these links. In this case, there is insufficient data to solve for a traffic matrix solution. Please check your interface traffic file.

Another problem is if you did not add seed demands to the network. You can do so either by loading in the demand file via File>Read, or adding more demands into the network using Modify > Elements > Demands. Once this is done, restart the Traffic Matrix operation.