Abstract: A test system and method for providing a network simulator to simulate the packet delivery delay and loss dynamics of an network such as the Internet. The test system delays and drops packets delivered between host devices on the test system according to a trace profile of the actual network packet delivery dynamics. The trace profile is recorded using a network measurement system transmitting and measuring the delivery of packets on the network. The trace profile records the actual network packet delivery dynamics, which is utilized by the test system to simulate the network packet performance. Using the test system as a network simulator, developers of interactive network application can accurately develop and test the performance of interactive network applications under realistic network conditions.