Scheduling real-time messages in a Fibre Channel Arbitrated Loop

Abstract

This paper addresses the problem of delivering real-time messages, both periodic and aperiodic, over a Fibre Channel Arbitrated Loop or FC-AL. Periodic messages typically have hard real-time constraints, whereas aperiodic messages are delivered as soon as possible. The deadlines of periodic messages are guaranteed by limiting the packet size under the access fairness algorithm defined in FC-AL. The aperiodic messages are delivered using a global server scheme based on the full duplex communication and transfer state facilitated in FC-AL. The algorithm presented in this paper is optimal in that it fully utilizes network bandwidth, while guaranteeing the respective deadlines of periodic messages.