Hardness and Approximation of the Survivable Multi-Level Fat Tree Problem

—With the explosive deployment of “triple play” (voice, video and data services) over the same access network, guaranteeing a certain-level of survivability for the access network is becoming critical for service providers. The problem of economically provisioning survivable access networks has given rise to a new class of network design problems, including the so-called SURVIVABLE MULTI-LEVEL FAT TREE problem (SMFT). We show that two special cases of SMFT are polynomialtime solvable, and present two approximation algorithms for the general case. The first is a combinatorial algorithm with approximation ratio min{ L/2 + 1, 2 log2 n} where L is the longest Steiner path length between two terminals, and n is the number of nodes. The second is a primal-dual (2∆s + 2)approximation algorithm where ∆s is the maximum Steiner degree of terminals in the access network. We then show that approximating SMFT to within a certain constant c > 1 is NPhard, even when all edge-weights of ...

• Type: Conference
• Year: 2009
• Where: INFOCOM
• Authors: Hung Q. Ngo, Thanh-Nhan Nguyen, Dahai Xu
• Keywords: Access Network, Approximation Algorithms, Communications, INFOCOM 2009, Survivable Access Networks