Applicability of MIMO as metric for frame latency

ATM frame latency is one of the main QoS parameters and consequently an important target in performance testing. We compare MIMO (message in message out), a new metric for measuring frame latency, versus other metrics and in particular versus LCD (last cell delay). Analysis of examples as well as measurement results demonstrate that MIMO is less affected by test workload and is a better indicator of the switch performance, in particular for out-of-service testing. We show how to aggregate MIMO for a network of switches. The expression of MIMO aggregation clearly indicates the contribution of each network element and their interconnections to the total frame latency