Performance modeling and analysis of hypoexponential network servers

Hypoexponential servers are commonly seen in today’s computer and communication networks whereby incoming packets are processed by the network server in multiple stages with each stage having a different processing time. This paper presents an analytical model to capture the behavior and subsequently analyze the performance of these network servers or similarly behaving systems. From our model, we derive key performance measures and features which include CPU utilization, system idleness, mean throughput, packet loss, mean system and queuing packet delays, and mean system and queue sizes. In addition, we present two popular finite queueing models (namely, M / D / 1 / K and M / M / 1 / K) to approximate our hypoexponential model. Results show that the both of these approximate models give close results when the system queue size is large.