Abstract: An arrangement for testing flow control logic in a network device such as a network switch includes a traffic generator configured for transmitting pause frames having prescribed pause values. The network device is configured for continuously transmitting data frames on a network medium. The traffic generator is configured for outputting a first pause frame to the network device that specifies a first pause interval on the order of ten minutes, followed by outputting during the first pause interval a second pause frame specifying a second pause interval substantially less than the first pause interval, for example on the order of ten seconds. The traffic generator is configured for measuring a time interval between transmission of the first pause frame and reception of subsequent data frames from the network device for evaluation of the flow control logic. Hence, the traffic generator can determine whether the second pause frame causes the flow control logic to cancel the first pause frame.