An efficient scheduling discipline for packet switching networks using earliest deadline first round robin*

In this paper we propose a frame-oriented scheduling discipline, EDF-RR (earliest-deadline-first round-robin), for OQ (output-queued) switch architecture and data traffic consisting of fixed-length cells. Bandwidth reservation for an active session is performed by holding a number of cell slots for the session in frames. Each cell that is going to be transferred in a frame is assigned a virtual release time and a virtual deadline according to the bandwidth reservation scheme. The transmitting order of the cells in frames is thus determined by nonpreemptive nonidling EDF algorithm so that cells of a backlogged session in frames are distributed as uniformly as possible. Through the analysis applying real-time scheduling theory and network calculus as well as network simulation, EDF-RR takes the advantage of low computational complexity, and possesses tight delay bounds and lenient buffer requirements. The proposed scheduling discipline is appropriate for distributed real-time systems as we show that sessions can be configured based on message traffic models and deadline requirements. Also, a modified version of EDF-RR, called EDF-DRR, can be applied as traffic regulator when jitter requirements exist among active sessions.