Joint Routing and Wavelength Allocation Subject to Absolute QoS Constraints in OBS Networks

From the network layer perspective, the problem of burst losses is one of the most challenging problems which restrain the development of optical burst switching (OBS) networks. Indeed, OBS is a buffer-less technology and the consequent lack of guarantees for data delivery may affect significantly the quality of service (QoS) perceived by end users. To overcome these obstacles, dedicated network mechanisms and design methods are required for QoS provisioning in the network. With this end in view, in this paper, we present a traffic engineering (TE) approach to support the end-to-end traffic delivery with absolute QoS guarantees, in terms of burst losses, in an OBS network. We focus on the establishment of explicit routing paths and minimum allocation of wavelength resources in network links under the requirement that certain absolute level of burst loss probability for a given set of traffic demands is guaranteed. In this paper, we call such an off-line problem the virtual topology (VT) design problem. Since the VT design problem is NP-complete, as an alternative to the mixed integer linear programming formulation, we develop a local search heuristic algorithm to solve it. Moreover, we focus on a dynamic OBS network scenario, where the offered traffic is subject to a change. In this context, we propose an on-line VT maintenance mechanism that is responsible for traffic admission control and adaptation of the VT to traffic changes. Eventually, proposed algorithms and mechanisms for the TE-driven end-to-end QoS approach are verified both numerically and by means of network simulations for a number of network scenarios.

I. Introduction

Optical burst switching has attracted considerable interest as an all-optical network architecture able to support efficiently the transport of IP packet traffic and which provides flexible access to the immense bandwidth of the optical fiber and the wavelength division multiplexing (WDM) technology [2], [3]. Optical burst switching (OBS) achieves subwavelength granularity of transmission and switching by assembling groups of IP packets into optical data bursts and reserving wavelength channels in WDM links for the time period just enough for the burst transmission.