Question

Some IERs in my network are failed. How do I go about finding the causes of failure?

Answer

There are many sources from which you can gather information about the IERs, some of them are:

(a) Evaluate in Capacity Planner: Choose "Evaluate..." from the Capacity Planning menu. A web report is produced. Look at the section on Traffic Performance, Time intervals with failures for details about the traffic failures. Say, you have a network where IP data is going over a Promina network and the CP report says that no route is found at the IP layer, then one of the things to check would be the Promina circuit defined between the IP routers at the source and destination. Check that the circuit has indeed been defined (from the Configuration OPFAC), is active and has enough bandwidth to accommodate the traffic.

(b) Logical Views: Logical views give you very similar information to what you get from the Capacity Planner report, but it is presented in a graphical form. Say, in the above network the Promina circuit has not been setup. If you view the IP layer logical view, you will see that the source and destination routers are not connected, i.e. no path at the IP layer.

(c) IER files: These are text files that record IER (and thread, if using threaded IERs) details and are located in the results folder inside the scenario folder. The <project>-<scenario>.ier_fail has a listing of all the failed IERs with details, including the reason for failure. Sometimes, the reason could sound very generic (depending on where exactly the failure was detected), but it is usually a good starting point. Say, the reason for failure is "Unable to find valid SE". You need to check the source and destination devices. It is possible that you are attempting to send a Top Secret message over Unclassified equipment -- which won't work (with the default decision table settings).

(d) DES log: Any protocol issues encountered by the simulation are logged in the file <project>-<scenario>.nt.lo which is located in the scenario folder. This file can also be accessed from the DES -> Open DES log menu.

(e) DES stats: DES statistics can be very valuable in troubleshooting your network. Say IERs are not going through and you suspect that the packets are being dropped somewhere in the network. One quick way to find out where the packets are being dropped could be to collect link statistics for the various links and see where throughput becomes zero. Once you know what device is dropping packets, it might be straight-forward to figure out the reason.