A fault recovery system that is fast and reliable is essential to today's networks, as it can be used to minimize the impact of the fault on the operation of the network and the services it provides. This paper proposes a methodology for performing automatic protection switching (APS) in optical networks with arbitrary mesh topologies in order to protect the network from fiber link failures. All fiber links interconnecting the optical switches are assumed to be bidirectional. In the scenario considered, the layout of the protection fibers and the setup of the protection switches is implemented in nonreal time, during the setup of the network. When a fiber link fails, the connections that use that link are automatically restored and their signals are routed to their original destination using the protection fibers and protection switches. The protection process proposed is fast, distributed, and autonomous. It restores the network in real time, without relying on a central manager or a centralized database. It is also independent of the topology and the connection state of the network at the time of the failure.

Commercial telecommunications networks have tight real-time requirements for restoration after a failure. The problem of finding the available restoration paths and reassigning the interrupted traffic within such tight real-time requirements places difficult demands on the restoration protocol employed. This paper reviews several distributed network restoration protocols and presents a new distributed protocol called RREACT, for performing this function with a distributed algorithm which uses no prior network status or topography knowledge and which supports multiple simultaneous link restorations. Simulation results show that this protocol significantly outperforms other existing algorithms based on the Sender-Chooser approach, usually completing the total restoration in well under one second. In addition, enhancements to the basic algorithm are described which help to ensure near-optimal use of network spare channel resources and address such restoration situations where a complete r...

Four distributed link restoration algorithms are analyzed in detail using a set of important performance metrics and functional characteristics. The functional characteristics are used to explain how these algorithms function and provide insight into their performance. The analysis and simulation results indicate that the Two Prong link restoration algorithm, which is based on issuing aggregate restoration requests from both ends of the disruption and on an intelligent backtracking mechanism, outperforms the other three algorithms in terms of restoration time. The RREACT link restoration algorithm consistently found paths that use fewer spares. I.

Broadband networks based on ATM or SONET/SDH will provide flexible switching and multiplexing for a diverse mix of traffic between O-D pairs. This paper presents a VP-based distributed method of bandwidth allocation that may be applied to handle dynamically changing traffic load patterns in such a network.

The proposed research deals with the development of algorithms and simulation tools for the design and analysis of network survival approaches. A software simulation system called NETSIM was built to facilitate the construction of network models and the fast distributed network restoration algorithms. With NETSIM, we have designed and implemented three distributed network restoration algorithms: Two Prong path-based restoration algorithm (Two Prong), One Prong path-based restoration algorithm (One Prong), and a modified version of Grover's Self-Healing Network (SHN) algorithm (modified SHN). To evaluate the efficiency of these algorithms in terms of spare capacity usage, a front end interface to Bertseka and Tseng's Relax-III code was implemented to calculate the optimal spare usage for a given link break. A graphical user interface program, called nstool, was built to edit the network topology and status. It also provides an easy to use panel to allow user to specify the restoration a...

: Intense competition between transport network service providers and the widespread deployment of vulnerable high-capacity fiber optic transport facilities has created the need for networks with short restoration times. This paper presents an optimized distributed real time path restoration mechanism, named OPRA, capable of restoring network failures quickly with performance close to centralized multi-commodity max-flow. OPRA synthesizes restoration pathsets by autonomous, database-free, self-organizing interaction between nodes. Simulation results predict that OPRA will restore network failures in very minimally redundant networks in less than two seconds. I. Introduction A. Background The development of Digital Crossconnect Systems (DCS), and networks with physically diverse routes, promotes the use of mesh restoration techniques. Mesh-based survivable network architectures exploit the intelligence of DCS-based transport networks to minimize the amount of spare capacity required ...

this article, we will use the term network reliability in a broad sense and cover several subtopics. We will start with network availability and performability, and then discuss survivable network design, followed by fault detection, isolation, and restoration as well as preplanning. We will conclude with a short discussion on recent issues and literature.

The evolution of applications with high throughput requirements (e.g. grid computing, medical applications, immersive teleconferencing) is constantly raising the demand for high-bandwidth network technologies. In today’s spectrum of technologies, this essentially translates in pushing the deployment of optical networks. As the deployment of wavelength multiplexing technology