QoS Routing under Multiple Additive Constraints: A Generalization of the LARAC Algorithm

Consider a directed graph G(V; E), where V is the set of nodes and E is the set of links in G. Each link (u; v) is associated with a set of k C 1 additive nonnegative integer weights C_uv D (cuv;w¹ uv;w² _uv; : : : ;wk _uv). Here, c_uv is called the cost of link (u; v) and wi _uv is called the ith delay of (u; v). Given any two distinguish nodes s and t, the QoS routing (QSR) problem QSR(k) is to determine a minimum cost s-t path such that the ith delay on the path is atmost a specied bound. This problem is NP-complete. The LARAC algorithm based on a relaxation of the problem is a very efficient approximation algorithm for QSR(1). In this paper, we present a generalization of the LARAC algorithm called GEN-LARAC. A detailed convergence analysis of GEN-LARAC with simulation results is given. Simulation results provide an evidence of the excellent performance of GEN-LARAC.We also give a strongly polynomial time approximation algorithm for the QSR(1) problem.