Scheduling multicasts on unit-capacity trees and meshes

Abstract

This paper studies the multicast routing and admission control problem on unit-capacity tree and mesh topologies in the throughput-model. The problem is a generalization of the edge-disjoint paths problem and is NP-hard both on trees and meshes. We study both the offline and the online version of the problem: In the offline setting, we give the first constant-factor approximation algorithm for trees, and an O((log log n)^2)-factor approximation algorithm for meshes. In the online setting, we give the first polylogarithmic competitive online algorithm for tree and mesh topologies. No polylogarithmic-competitive algorithm is possible on general network topologies [Bartal,Fiat,Leonardi, 96], and there exists a polylogarithmic lower bound on the competitive ratio of any online algorithm on tree topologies [Awerbuch,Azar,Fiat,Leighton, 96]. We prove the same lower bound for meshes