 
Summary: BuyatBulk Network Design
Baruch Awerbuch \Lambda Yossi Azar y
Department of Computer Science Department of Computer Science
Johns Hopkins University Tel Aviv University
Baltimore, MD 21218 Tel Aviv 69978, Israel
Abstract
The essence of the simplest buyatbulk network
design problem is buying network capacity ''whole
sale'' to guarantee connectivity from all network
nodes to a certain central network switch. Capac
ity is sold with ''volume discount'': the more ca
pacity is bought, the cheaper is the price per unit
of bandwidth. We provide O(log 2 n) randomized
approximation algorithm for the problem. This
solves the open problem in [15]. The only pre
viously known solutions were restricted to special
cases (Euclidean graphs) [15].
We solve additional natural variations of the
problem, such as multisink network design, as
well as selective network design. These problems
