The technology disclosed includes a software architecture for methods and devices used to test routers, switches and the like, particularly high volume infrastructure devices. In particular, this architecture associates test data stream definitions with emulated devices that send test frames or packets to and receives them from a system or device under test (“DUT”). By relating the test data stream definitions to definitions of the emulated devices that are coupled to the DUT, automation of test frame and/or test packet design improves, especially where some of the information needed to generate test frames and/or packets is dynamically generated during a test.