Energy consumption of the telecommunication networks contributes to a large portion of the greenhouse gas
(GHG) emissions due to the global electricity consumption. Furthermore, backbone networks dominate the
energy consumption of the telecommunication networks by high peak data rates. In this paper, we enhance
our previously proposed energy-efficient availability design scheme for IP over WDM (IP/WDM) networks, i.e.,
Power-Aware Reliable Design (PARD).1 Here, PARD-QoP is proposed which incorporates Quality of Protection
(QoP) with power-aware reliable IP/WDM Network design. According to the QoP concept, each connection
demand specifies a working bandwidth capacity requirement and a minimum backup capacity requirement. We
evaluate the performance of PARD-QoP under the 14-node NSFNET topology for six QoP classes that are
uniformly distributed among the connection requests and for various demand sizes. The simulation results show
that PARD-QoP enhances its predecessor PARD by 7%-12% in terms of Capital Expenditure (CAPEX), denoting
the number of wavelength channels, and by 4%-8% in terms of Operational Expenditure (OPEX), denoting the
energy consumption. Moreover, PARD-QoP is shown to differentiate the demands in three availability classes as
99.9%, 99.99% and 99.999% with respect to the backup bandwidth requirements.
For a source-destination pair to communicate in a connection-oriented wavelength-routed optical network, a connection in the optical layer between the two nodes must be established. This process, also known as Routing and Wavelength Assignment (RWS), is realized by selecting a path between the two end nodes and allocating a suitable wavelength. The aim of the RWA process is to find routes and assign wavelengths for connection requests in a way that minimizes the consumption of network resources, while at the same time ensuring that no two lightpaths are assigned the same wavelength on a shared fiber link. Routing and wavelength assignment in wavelength-routed WDM networks is a major design issue, especially when survivability is a requirement. To minimize resources in such networks operating under static traffic environment, the problems of routing and wavelength assignment must be solved jointly as a single problem. This study proposes a different approach to formulate the problems of routing and wavelength assignment as Integer Linear Programming (ILP) problem. Unlike other formulations, where the routing sub-problem and wavelength assignment sub-problem are considered separately, this approach addresses the RWA problem compounded. Although this approach increases the number of variables in the problem, it guarantees the optimal solution. Furthermore, the problem may in many cases be solved using simpler linear programming techniques.
Explosion of data and mass availability of Internet connections around the globe had created huge bandwidth requirements for bandwidth hungry applications. Despite the technological advances in the core and their ability to transport, still much work has to be done in the access networks in order to be able to let the broadband traffic be transmitted transparently. Current solutions for access networks do not provide a concrete solution for the famous last mile problem. In this review we will investigate optical access networks as viable solutions to the ongoing problems in the access networks. Further we will study physical and technological limitations with the current state-of-the-art optical technology. We will address the optical access networks promises in responding to these shortcomings. We will thoroughly study passive optical networks (PONs), reviewing different type of PONs considering their benefits and limitations. We will conclude our study with comparison of these current solutions.
In this paper, we propose a new wavelength-reservation-based dynamic routing and wavelength assignment algorithm (RWA) to improve the fairness of previous RWA algorithms in wavelength-routed WDM networks. In the algorithm, RWA solutions available from static optimal virtual topology design are used to determine a set of wavelengths to be reserved on corresponding routes for each node pair. Based on the wavelength reservation, a set of dynamic wavelength allocation policies is proposed to use the reserved wavelengths efficiently by allowing the reserved wavelengths to be used by others. Simulation results based on NSFNET topology show that a modified RWA algorithm based on wavelength reservation can improve the fairness of the original RWA algorithm and can reduce the overall blocking probability when traffic load is low.
Fixed routing is favoured because it simplifies physical layer engineering, such as link budget calculations. The use of the fixed routing scheme can achieve fast bandwidth provisioning at the expense of inferior network blocking performance and lack of adaptability to traffic variation. In this paper, a load-balanced fixed routing scheme is proposed. For each source-destination pair, it assigns a fixed path such that the load-balancing requirement is met. This scheme is formulated into an Integer Linear Programming process. Both simulation and analytical methods are used to verify the effectiveness of the proposed planning algorithm. We also modify an analytical model of blocking probability by considering the load-balancing characteristic.
This paper studies the virtual topology design of wavelength-routed WDM networks. The focus is on the virtual topology design problem taking into account the quality of service (QoS) requirements of different user applications. To provide diverse QoS levels to meet different QoS requirements, we first propose a QoS model for WDM networks, in which we define four types of optical connections, each providing a diverse QoS level in terms of the transmission bandwidth and end-to-end delay. Correspondingly, we classify the network traffic into four categories with different QoS requirements for using the four types of connections. Based on this QoS model, we then formulate the virtual topology design problem as a linear programming problem with an objective to maximize the network throughput, and give an exact formulation of the problem.
This paper solves the problem of path selection for WDM mesh networks with a special focus on the implementation in middle-sized networks, such as metropolitan-area networks (MANs). A novel routing and signaling protocol, called Asynchronous Criticality Avoidance (ACA), is proposed to improve the network performance. With the ACA protocol, a specific set of wavelength channels are defined as critical links between a node pair according to dynamic link-state. Criticality information is defined as the critical links and the associated information, which is coordinated and disseminated by each source node to every other source node as an inter-arrival planning. Routing and wavelength assignment is performed along with the criticality avoidance mechanism, in which path selection process is devised to take the criticality information into consideration. Simulation is conducted in 22- and 30-node networks to examine the proposed approach. The simulation results show that the ACA protocol significantly outperforms the Fixed-Path Least-Congested (FPLC) scheme under the Fixed Alternate Routing architecture with various patterns of alternate paths assigned to each source-destination pair in the networks.
Survivability and continuity of service to the end users during the occurrence of failure have evolved to be a critical issue in the aspect of control and management of the next-generation Internet. The ordinary path-based and link-based shared protection schemes can only provide a limited spectrum of protection services with coarse protection granularity, which will not be able to satisfy the versatile requirements of multimedia applications on the Internet in the foreseeable future. In this paper we propose a framework, Short Leap Shared Protection (SLSP), for service-guaranteed end-to-end shared protection for the optical Internet. We will describe the algorithm for implementing this idea in detail and show that SLSP enhances the 1:N and M:N shared protection schemes in terms of scalability, flexibility and class of service.
Control architectures have recently been proposed to aid in unifying the packet and optical layers, with a goal of enabling network efficiency and operational simplicity for Internet service providers. Network applications that use the inter-layer information and control interfaces of these architectures are examined and analyzed for their value to different service providers and for their fit within the architectural models.