PROCEDURE FOR CORRECT COMPARISON OF CAR AND WFQ COUNTERS

When a comparison is needed between CAR counters (*) and WFQ counters (^) the only way to make correct measures is to force congestion on the interface to which WFQ is attached 100% of the time during the test, this because WFQ counters are only updated in case of congestion.
Congestion can be easily forced by running 1 UDP stream at a rate which exceeds the line rate. For example, if the line rate is 2 Mbps and mgen is the UDP traffic generator, possible mgen options are:

   -s 1000 -r 200

(*) with CAR counters we intend the information related to conformed and exceeding traffic which is displayed through the command:

   show int _interface_ rate-limit

(^) with WFQ counters we mean the information about the number of "matched" packets per class which can be displayed through the command

   show policy int _interface_

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