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An improved algorithm for CIOQ switches # Yossi Azar + Yossi Richter #

Summary: An improved algorithm for CIOQ switches #
Yossi Azar + Yossi Richter #
The problem of maximizing the weighted throughput in various switching settings has been
intensively studied recently through competitive analysis. To date, the most general model
that has been investigated is the standard CIOQ (Combined Input and Output Queued) switch
architecture with internal fabric speedup S # 1. CIOQ switches, that comprise the backbone of
packet routing networks, are N ×N switches controlled by a switching policy that incorporates
two components: Admission control and scheduling. An admission control strategy is essential to
determine the packets stored in the FIFO queues in input and output ports, while the scheduling
policy conducts the transfer of packets through the internal fabric, from input ports to output
ports. The online problem of maximizing the total weighted throughput of CIOQ switches
was recently investigated by Kesselman and Ros’en in [15]. They presented two di#erent online
algorithms for the general problem that achieve non­constant competitive ratios (linear in either
the speedup or the number of distinct values, or logarithmic in the value range). We introduce
the first constant­competitive algorithm for the general case of the problem, with arbitrary
speedup and packet values. Specifically, our algorithm is 8­competitive, and is also simple and
easy to implement.
1 Introduction
Overview: Recently, packet routing networks have become the dominant platform for data trans­


Source: Azar, Yossi - School of Computer Science, Tel Aviv University


Collections: Computer Technologies and Information Sciences