Summary: On­Line Routing of Virtual Circuits with
Applications to Load Balancing and Machine
Scheduling \Lambda
James Aspnes y Yossi Azar z Amos Fiat x
Serge Plotkin -- Orli Waarts k
Abstract
In this paper we study the problem of on­line allocation of routes to virtual circuits (both
point­to­point and multicast) where the goal is to route all requests while minimizing the
required bandwidth. We concentrate on the case of permanent virtual circuits (i.e., once a
circuit is established, it exists forever), and describe an algorithm that achieves an O(logn)
competitive ratio with respect to maximum congestion, where n is the number of nodes in
the network. Informally, our results show that instead of knowing all of the future requests,
it is sufficient to increase the bandwidth of the communication links by an O(logn) factor.
We also show that this result is tight, i.e. for any on­line algorithm there exists a scenario
in which
\Omega\Gamma137 n) increase in bandwidth is necessary in directed networks.
We view virtual circuit routing as a generalization of an on­line load balancing problem,
defined as follows: jobs arrive on line and each job must be assigned to one of the machines
immediately upon arrival. Assigning a job to a machine increases this machine's load by
an amount that depends both on the job and on the machine. The goal is to minimize the

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

Collections: Computer Technologies and Information Sciences; Physics