a device would perform under pathological network conditions such as broadcast storms. Latency: Measures the round-trip time taken by a test frame to travel through a network device or across the network and back to the test port. Latency is the time interval that begins when the last bit of the input frame reaches the input port and ends when the first bit of the output frame is seen on the output port. It is the time taken by a bit to go through the network and back. Latency variability can be a problem. With protocols like voice over Internet protocol (VoIP), a variable or long latency can cause degradation in voice quality. System reset: Measures the speed at which a DUT recovers from a hardware or software reset. This subtest is performed by measuring the interruption of a continuous stream of frames during the reset process. System recovery: Measures the speed at which a DUT recovers from an overload or oversubscription condition. This subtest is performed by temporarily oversubscribing the device under test and then reducing the throughput at normal or low load while measuring frame delay in these two conditions. The difference between delay at overloaded condition and the delay and low load conditions represent the recovery time. From a laboratory and benchmarking perspective, the RFC 2544 methodology is an ideal tool for automated measurement and reporting. From a service turn-up and troubleshooting perspective, RFC 2544, although acceptable and valid, does have some drawbacks: Service providers are shifting from only providing Ethernet pipes to enabling services. Networks must support multiple services from multiple customers, and each service has its own performance requirements that must be met even under full load conditions and with all services being processed simultaneously. RFC 2544 was designed as a performance tool with a focus on a single stream to measure maximum performance of a DUT or network under test and was never intended for multiservice testing. With RFC 2544's focus on identifying the maximum performance of a device or network under test, the overall test time is variable and heavily depends on the quality of the link and subtest settings. RFC 2544 test cycles can easily require a few hours of testing. This is not an issue for lab testing or benchmarking, but becomes a serious issue for network operators with short service maintenance windows. Packet delay variation is a key performance indicator