A network switching device (101) for quantifying available service-level capacity of a network (201) for projected network traffic. The network switching device (101) includes at least one input port (110-1a), at least one output port (110-6a), at least one packet-handling module, and at least one test-packet module. At least one packet-handling module is coupled to an input port (110-1a) and an output port (110-6a). At least one test-packet module is coupled with at least one network switching-device module. The test-packet module is to affect presence of a test packet in the network (201) for quantifying available service-level capacity of the network (201) for projected network traffic. A packet-injection system and method for quantifying available service-level capacity of the network (201) for projected network traffic are also provided.