A Specific Scheme for Rate-Controlled Smooth Scheduling Based on Timeslot-Iteration

Packet schedulers are the key to guarantee quality of service in computer networks. The rate-controlled EDF schedulers embrace the good characteristics of output smoothness. But the methods used in the existing EDF schedulers to calculate eligible time are based on a real or virtual global system time, which is too complex to be implemented in high-speed networks. The paper presents a specific and practical scheme to implement a timeslot based EDF scheduler which named TiRSS (Rate-controlled Smooth Scheduling Based on Timeslot-iteration). In order to avoid the dependence of the global system time, TiRSS apply a new feasible state tracking mechanism which update the state of queues along with the scheduling timeslot iteratively. Theory analysis proved the state tracking mechanism can accurately track the process of packet transmitting in the ideal scheduling model. Through this counting mechanism combined with EDF scheduling principle, TiRSS realizes a practical implementation to EDF scheduler based on timeslot-iteration. The sufficient theoretical analysis and simulation results show that TiRSS is reasonable and effective.