 
Summary: Maximizing Throughput in MultiQueue Switches
Yossi Azar
Arik Litichevskey
Abstract
We study a basic problem in MultiQueue switches. A switch connects m input ports to a
single output port. Each input port is equipped with an incoming FIFO queue with bounded
capacity B. A switch serves its input queues by transmitting packets arriving at these queues,
one packet per time unit. Since the arrival rate can be higher than the transmission rate and
each queue has limited capacity, packet loss may occur as a result of insufficient queue space.
The goal is to maximize the number of transmitted packets. This general scenario models most
current networks (e.g., IP networks) which only support a "best effort" service in which all
packet streams are treated equally. A 2competitive algorithm for this problem was designed
in [5] for arbitrary B. Recently, a 17
9 1.89competitive algorithm was presented for B > 1 in
[3]. Our main result in this paper shows that for B which is not too small our algorithm can do
better than 1.89, and approach a competitive ratio of e
e1 1.58.
1 Introduction
Overview: Switches are a fundamental part of most networks. Networks use switches to route
packets arriving at input ports to an appropriate output port, so that the packets will reach their
