In wavelength-division-multiplexing networks, the fault-tolerance is very important since failures may lead to a significant amount of data loss. At the same time, the waveband switching technique is very interesting since it can save switching ports in optical cross-connections. In addition, the hierarchical routing in multidomain optical networks is very challenging since the interdomain routing is based on aggregative virtual topology. However, previous works did not jointly consider the three issues. We propose two schemes, segment-based protection (SBP) and path-based protection (PBP), to provide the fault-tolerance and waveband grooming in multidomain optical networks. In SBP, for each connection we first compute an interdomain loose route based on virtual topology, and then we compute the intradomain exact path-pairs in each single domain traversed by the loose route based on physical topology. In PBP, for each connection we first compute an interdomain loose primary path and an interdomain loose backup path based on virtual topology, and then we compute the intradomain exact paths in each single domain traversed by the loose primary path and backup path based on the physical topology. To support multidomain waveband grooming, we present the layered auxiliary graph. Simulation results show that PBP performs better than SBP.
As a special case of p cycles, a Hamiltonian cycle protection scheme is proposed to achieve fast failure restoration and simple management in fault-tolerant networks. We extend the idea of a Hamiltonian cycle protection scheme to fault-tolerant wavelength-division-multiplexing (WDM) optical fiber networks, and propose a new Heuristic Hamiltonian cycle protection algorithm (HHCPA) to tolerate the single-fiber failure. In the HHCPA, we consider the idea of differentiated protection for different-level demands, i.e., high-level demands with protection requirements and low-level demands without protection requirements. We also develop the link-cost function to achieve the load balancing and proper link selection in computing the light paths for each demand to effectively reduce the backup wavelength consumption. Simulation results show that, compared to conventional algorithm, the HHCPA can obtain significant performance improvement in resource utilization ratio and blocking probability.
Supporting QoS (Quality of Service) and improving bandwidth utilization are necessary in IP/DWDM optical Internet. In this paper, with the introduction of game theory and layered graph, a static traffic grooming scheme is proposed based on artificial immune algorithm to minimize network resource occupancy and maximize comprehensive QoS satisfaction degree, achieving Nash equilibrium between network provider utility and user utility. Simulation results have shown that the proposed scheme is both feasible and effective.
IP over DWDM optical Internet is one of the main networking techniques for NGI (Next Generation Internet), and how to improve its fault-tolerance capability and QoS (Quality of Service) becomes critical. Fault-tolerant QoS routing is one of the effective solutions. In this paper, a reactive fault-tolerant integrated QoS unicast routing scheme is proposed based on heuristic A algorithm to deal with the case of single-link/single-node failure. Its objective is to make the best balance among delay, load and the cost of wavelength conversion, trying to improve the wavelength utilization and failure restoring rate. Simulation results have shown that the proposed scheme is both feasible and effective.
A Quality of Service (QoS) multicast routing algorithm in IP/DWDM optical Internet is proposed in this paper, taking QoS requirement and cost into account. Due to the NP-hard nature of this problem, a QoS and cost optimized or sub-optimized multicast routing tree is constructed based on tabu-hierarchy genetic algorithm with network load balance supported. Simulation results have shown that the proposed algorithm is both feasible and effective, and is advantageous over its counterpart based on the traditional genetic algorithm.
IP/DWDM optical Internet is considered to be one of the most potential candidates for NGI (Next Generation Internet) backbone. However, the bottlenecks caused by the electronics still exist. A solution to this problem is to design an optimal virtual topology. In this paper, a novel virtual topology design method is presented, minimizing the sum of traffic-weighted hop count. Based on the given physical topology and the specific traffic matrix, the corresponding virtual topology is designed, and then, over which the traffic is routed. Due to its NP-hard nature, the design problem is decomposed into three subproblems: virtual topology construction, wavelength assignment and traffic routing, which are solved with heuristic algorithms respectively. To verify the feasibility and the effectiveness of the proposed method, a simulation environment is developed and simulation has been done over some actual network topologies. Simulation results have shown that the proposed method is both feasible and effective.
IP/DWDM optical Internet is considered to be a promising candidate for Next Generation Internet backbone. Fault-tolerant mechanisms have become critical technologies in IP/DWDM optical Internet. In this paper, based on preventive and reactive schemes, four fault-tolerant routing mechanisms in IP/DWDM optical Internet are proposed to deal with the problem of routing and wavelength assignment with dynamic single/multiple point failures under dynamic traffic demands, such as link/node/channel failures. The proposed mechanisms take load balancing into account, and a heuristic wavelength assignment algorithm is introduced to reduce the end-to-end delay. Simulation results have shown that the proposed fault-tolerant routing mechanisms are both feasible and effective.
The paper discusses integrated QoS multicast routing and wavelength assignment algorithm in IP/DWDM Internet. Given a QoS multicast request with the bandwidth requirement, the multicast end-to-end delay and the delay variation bounds, we propose an algorithm, which can find a QoS-based multicast tree satisfying the above three constraints. The proposed algorithm constructs the multicast tree based on logical topology generated from physical topology. The logical topology is similar to the wavelength graph. Thus, the search process of the multicast tree means finding both route and available wavelength. By this way, the proposed algorithm integrates routing and wavelength assignment into a single process. We explain the correctness of the algorithm finally.
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