One example method occurs at a test system implemented using at least one processor, the method comprising: sending, via an application programming interface (API) and to a first traffic generator, a first instruction for setting a rate of background test packets sent to or via a system under test (SUT) for a test session; sending the background test packets to or via the SUT during the test session; receiving, from at least one feedback entity, feedback indicating at least one traffic metric associated with the background test packets sent to or via the SUT during the test session; generating, using the feedback, a second instruction for adjusting the rate of background test packets sent during the test session; and providing, via the API and to the first traffic generator, the second instruction for adjusting the rate of background test packets sent to or via the SUT during the test session.