Connection Management in High-Speed Interconnection Systems

High-speed interconnection systems for linking high-performance computers with each other and with their intelligent peripheral devices have gained great importance in recent years. The HIPPI standard which governs the interfaces to most of today's high-speed interconnection systems is a representative, standardized interconnection solution and its control and performance issues are consequently of particular interest. This paper examines the issue of connection management control for these interconnection systems. It describes the interconnection system environment, the characteristics of the traffic being carried, and the ensuing problem of efficient connection management. Different management policies are described, ranging from policies that require a complete knowledge of the whole interconnection system's state for their operation, to policies operating with only local client state knowledge. Considerations relevant to performance and switch implementation complexity trade-offs of the different policies are presented. Finally, priority access supporting connection management policies using preemptive and non-preemptive disciplines are described, and for the first time compared, using an analytic model introduced in this paper. Comparison of the two disciplines gives insights useful in choosing the preferred connection management policy and priority discipline, as a function of implementation objectives, the system's particular traffic characterization and its performance requirements.