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+ 1 additive nonnegative integer weights C
_uv
= (c
_uv
, w
_uv
¹
, w
_uv
²
,⋯, w
_uv
^k
). Here, c
_uv
is called the cost of link (u, v) and w
_uv
ⁱ
is called the i th 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 i
^th
delay on the path is atmost a specified 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.