On-line routing and wavelength assignment for dynamic traffic in WDM ring and torus networks

Abstract

We develop on-line routing and wavelength assignment (RWA) algorithms for WDM bidirectional ring and torus networks with N nodes. The algorithms dynamically support all k-allowable traffic matrices, where k denotes an arbitrary integer vector [k1, k2, ..., kN ], and node i, 1 ≤ i ≤ N , can transmit at most ki wavelengths and receive at most ki wavelengths. Both algorithms support the changing traffic in a rearrangeably nonblocking fashion. Our first algorithm, for a bidirectional ring, uses (N i=1 ki)/3 wavelengths in each ring direction and requires at most three lightpath rearrangements per new session request regardless of the number of nodes N and the amount of traffic k. When all the ki's are equal to k, the algorithm uses kN/3 wavelengths, which is known to be the minimum for any off-line rearrangeably nonblocking algorithm. Our second algorithm, for a torus topology, is designed for the special case with all the ki's equal to k. For a square torus network with N nodes, the algorithm uses k √ N/2 wavelengths in each fiber, which is shown to be at most two times a lower bound obtained by assuming full wavelength conversion at all nodes. In addition, the algorithm requires at most √ N −1 lightpath rearrangements per new session request regardless of the amount of traffic k.

Link Fault Localization Using Bi-Directional M-Trails in All-Optical Mesh Networks

“…Manhattan grids), in view of the information theoretical lower bound log 2 (|E| + 1) . Note that a 2D grid graph is similar to circulant graphs with every node of nodal degree 4, which have been recognized as excellent candidate topologies for highreliability network design in modern communication networks [18]- [21]. For example, circulant graphs of degree four have been considered for the design of WDM local networks and interconnection subsystems [18], [20], [21].…”

On-line routing and wavelength assignment for dynamic traffic in WDM ring and torus networks

“…Another type of problem formulation, referred to as the nonblocking formulation, assumes prior knowledge of the set of all the traffic matrices, or equivalently the traffic demands, to be supported [15], [16], [17], [18]. In [16], the set of traffic matrices is characterized by the maximum link load in the network.…”

Uniform vs. non-uniform band switching in WDM networks

“…T HE MAJORITY of the routing and switching literature for WDM networks has focused on how to minimize the total number of wavelengths [1], [2], [3], [4], [5], [6], [7], [8], since the number of wavelengths used specifies the amount of capacity required on each fiber. However, this single-resource approach does not take into account the switching necessary at each node which routes each call to its destination.…”