This paper proposes a novel linear formulation for the problem of segment shared protection, where the switching/merging nodes and the least-cost link-disjoint working and protection segments corresponding to each switching/merging node-pair are jointly determined for a connection request. A novel approach of <i>arc-reversal graph transformation</i> is introduced. We verify the ILP and compare it with three reported approaches for solving the segment shared protection problem, namely CDR, PROMISE, and OPDA, by launching dynamic connection requests on two network topologies. From the experiment results, we observe that the ILP can always yield better results in terms of the total cost taken by the working and protection segments. We conclude that the proposed ILP formulation is a step ahead of the most state-of-the-art techniques in solving the shared protection problem, which provides a means of evaluating any other segment shared protection algorithms.
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 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.