Scheduling Multirate Periodic Traffic in a Packet Switch

This paper explores scheduling multiclass periodic tra c with deadlines in a time slotted system through an N N switch Di erent tra c streams may have di erent periods and di erent rates Each packet must depart before the next packet in its stream arrives An algorithm is given to schedule all tra c if each period evenly divides all longer pe riods and if the utilization at each link is no larger than one Furthermore this algorithm can schedule all tra c with no restrictions on the periods if the link utilization does not exceed A simple greedy algorithm is presented and is shown to schedule all tra c with no restrictions on the periods if the link utilization does not exceed These two algorithms can also be applied to more general deterministically constrained tra c when the link utilization is at most and respectively James Giles and Bruce Hajek are with the Coordinated Science Laboratory and the Department of Electrical and Computer Engineering at the University of Illinois at Urbana Champaign Address of Corresponding Author Prof Bruce Hajek Coordinated Science Laboratory West Main Street Urbana IL USA Tel e mail b hajek uiuc edu