A real-time system is required to complete its work and deliver its sevices on a timely basis.We lays much emphasis on hard real-time characteristics of the system

because hard real-time performance is one important performance requirement of special system such as avionics network.The periodic task model is a well-known deterministic workload.With its various extensions

the model characterizes accurately many traditional hard real-time applications.Switched fabric is one of basic fibre channel topology.Fixed-length packet scheme is mainly used in fibre channel switches.Taking the study on fibre Channel switch fabric under hard real-time constraints as background

an optimization design of typical message set is proposed according to the weighted round-robin algorithm.It is derived and formally proved that the achievable utilization using the optimization design can be doubled at least.