Dynamic wavelength routing in multifiber WDM networks

The research, development, and deployment of wavelength division multiplexing (WDM) technology are now evolving at a rapid pace to fulfill the increasing bandwidth requirement and deploy new network services. Routing and wavelength assignment algorithms play a key role in improving the performance of wavelength-routed all-optical networks. We study networks with dynamic wavelength routing and develop accurate analytical models for evaluating the blocking performance under dynamic input traffic in different topologies. Two dynamic routing algorithms are first developed and the performances of the algorithms in single-fiber WDM networks are studied using both analytical models and simulation. We also develop efficient algorithms to optimally place a given number of wavelength converters on a path of a network. Finally we consider the effect of multiple fibers on WDM networks without wavelength conversion. We develop analytical models for evaluating the blocking performance of multifiber networks with fixed-path routing, alternate-path routing, and fixed-path least-congestion routing algorithms. The number of fibers required to provide high performance in multifiber networks with different routing algorithms are also studied

Fiber requirement in multifiber WDM networks with alternate-path routing

An important problem in multifiber WDM networks is to decide how many fibers per link are required to guarantee high network performance. The fiber requirement may depend on many factors, e.g., the network topology, traffic patterns, the number of wavelengths per fiber, and the routing algorithm employed in the network. We study the fiber requirement under dynamic traffic in different topologies with alternate path routing (APR) in this paper. A new analytical model is developed to evaluate the blocking performance of such networks. Our analytical and simulation results show that the number of required fibers per link to provide high network performance is slightly higher in the APR than the fixed-path routing (FPR). However, a small number of fibers per link are still sufficient to guarantee high network performance in both the regular mesh-torus networks and the irregular NSFnet with APR. Since multiple fibers have the same effect as limited wavelength conversion, our analytical model is also applicable in networks with limited wavelength conversion.This is a manuscript of a proceeding published as Li, Ling, and Arun K. Somani. "Fiber requirement in multifiber WDM networks with alternate-path routing." In Proceedings Eight International Conference on Computer Communications and Networks, pp. 338-343. IEEE, 1999. DOI: 10.1109/ICCCN.1999.805540. Posted with permission.</p

Fiber Requirement in Multifiber WDM Networks with Alternate-Path Routing

An important problem in multifiber WDM networks is to decide how many fibers per link are required to guarantee high network performance. The fiber requirement may depend on many factors, e.g., the network topology, traffic patterns, the number of wavelengths per fiber, and the routing algorithm employed in the network. We study the fiber requirement under dynamic traffic in different topologies with alternate path routing (APR) in this paper. A new analytical model is developed to evaluate the blocking performance of such networks. Our analytical and simulation results show that the number of required fibers per link to provide high network performance is slightly higher in the APR than the fixed-path routing (FPR). However, a small number of fibers per link are still sufficient to guarantee high network performance in both the regular mesh-torus networks and the irregular NSFnet with APR. Since multiple fibers have the same effect as the limited wavelength conversion, our analytical ..

Traffic grooming and wavelength conversion in optical networks

Wavelength Division Multiplexing (WDM) using wavelength routing has emerged as the dominant technology for use in wide area and metropolitan area networks. Traffic demands in networks today are characterized by dynamic, heterogeneous flows. While each wavelength has transmission capacity at gigabit per second rates, users require connections at rates that are lower than the full wavelength capacity. In this thesis, we explore network design and operation methodologies to improve the network utilization and blocking performance of wavelength routing networks which employ a layered architecture with electronic and optical switching. First we provide an introduction to first generation SONET/SDH networks and wavelength routing networks, which employ optical crossconnects. We explain the need and role of wavelength conversion in optical networks and present an algorithm to optimally place wavelength conversion devices at the network nodes so as to optimize blocking performance. Our algorithm offers significant savings in computation time when compared to the exhaustive method.;To make the network viable and cost-effective, it must be able to offer sub-wavelength services and be able to pack these services efficiently onto wavelengths. The act of multiplexing, demultiplexing and switching of sub-wavelength services onto wavelengths is defined as traffic grooming. Constrained grooming networks perform grooming only at the network edge. Sparse grooming networks perform grooming at the network edge and the core. We study and compare the effect of traffic grooming on blocking performance in such networks through simulations and analyses. We also study the issue of capacity fairness in such networks and develop a connection admission control (CAC) algorithm to improve the fairness among connections with different capacities. We finally address the issues involved in dynamic routing and wavelength assignment in survivable WDM grooming networks. We develop two schemes for grooming primary and backup traffic streams onto wavelengths: Mixed Primary-Backup Grooming Policy (MGP) and Segregated Primary-Backup Grooming Policy (SGP). MGP is useful in topologies such as ring, characterized by low connectivity and high load correlation and SGP is useful in topologies, such as mesh-torus, with good connectivity and a significant amount of traffic switching and mixing at the nodes