Survey of Routing Algorithms for Computer Networks

This thesis gives a general discussion of routing for computer networks, followed by an overview of a number of typical routing algorithms used or reported in the past few years. Attention is mainly focused on distributed adaptive routing algorithms for packet switching (or message switching) networks. Algorithms for major commercial networks (or network architectures) are reviewed as well, for the convenience of comparison

Protection and restoration algorithms for WDM optical networks

Currently, Wavelength Division Multiplexing (WDM) optical networks play a major role in supporting the outbreak in demand for high bandwidth networks driven by the Internet. It can be a catastrophe to millions of users if a single optical fiber is somehow cut off from the network, and there is no protection in the design of the logical topology for a restorative mechanism. Many protection and restoration algorithms are needed to prevent, reroute, and/or reconfigure the network from damages in such a situation. In the past few years, many works dealing with these issues have been reported. Those algorithms can be implemented in many ways with several different objective functions such as a minimization of protection path lengths, a minimization of restoration times, a maximization of restored bandwidths, etc. This thesis investigates, analyzes and compares the algorithms that are mainly aimed to guarantee or maximize the amount of remaining bandwidth still working over a damaged network. The parameters considered in this thesis are the routing computation and implementation mechanism, routing characteristics, recovering computation timing, network capacity assignment, and implementing layer. Performance analysis in terms of the restoration efficiency, the hop length, the percentage of bandwidth guaranteed, the network capacity utilization, and the blocking probability is conducted and evaluated

PATHALIAS, or, The Care and Feeding of Relative Addresses

Pathalias computes electronic mail routes in environments that mix explicit and implicit routing, as well as syntax styles. We describe the history of pathalias, its algorithms and data structures, and our design decisions and compromises. Pathalias is guided by a simple philosophy: get the mail through, reliably and efficiently. We discuss the principles of routing in heterogeneous environments necessary to make this philosophy a reality

PATHALIAS or The Care and Feeding of Relative Addresses

Pathalias computes electronic mail routes in environments that mix explicit and implicit routing, as well as syntax styles. We describe the history of pathalias, its algorithms and data structures, and our design decisions and compromises. Pathalias is guided by a simple philosophy: get the mail through, reliably and efficiently. We discuss the principles of routing in heterogeneous environments necessary to make this philosophy a reality.http://deepblue.lib.umich.edu/bitstream/2027.42/107874/1/citi-tr-86-2.pd

Intelligent Routing for Software-Defined Media Networks

The multimedia market is an industry with an ever-growing demand coupled with strict requirements. Be it in live streaming services or file content broadcast, multimedia providers need to deliver the best possible quality in order to meet their costumer’s requirements and gain or keep their trust. Multimedia traffic has a high impact on networks and, due to its nature, is sensitive to congestion or hardware failure. Thus, it is frequently that multimedia providers resort to third-party software to monitor quality parameters. Skyline Communications’ DataMiner® offers network monitoring, orchestrating and automation capabilities across a broad range of applications and environments. These features are enabled by the emergence of Software-Defined Networking (SDN) which provides a global view of networks and the ability to change network properties through software applications. This contrasts with traditional networks which are rigid, static and difficult to scale-up. An application that greatly benefits from the global network view of SDN is routing optimization. Through routing optimization, a network can effectively deliver more traffic by efficiently balancing load across the different links and paths between end points of a service, reaching an increased performance in data transport. This dissertation comes to light with the goal of optimizing DataMiner’s routing mechanism by exploring the routing optimization possibilities enabled by its SDN-like architecture. Both link cost optimization-based and Machine Learning (ML) approaches are evaluated as possible solutions to Skyline’s problem and several experiments were conducted to compare them and understand their impact on network performance while transporting multimedia streams.O mercado audiovisual é uma indústria onde a procura está em constante crescimento, bem como a exigência. Tanto durante transmissões ao vivo como de conteúdo multimédia pré-gravado, os provedores de multimédia necessitam de garantir a melhor qualidade possível para corresponderem aos requisitos dos seus clientes e conquistarem ou manterem a sua confiança nos seus serviços. O tráfego multimédia tem um forte impacto nas redes que o transportam e, graças à sua natureza, é bastante sensível a congestão ou a falhas de equipamento. Por este motivo, é frequente os provedores de multimédia recorrerem a aplicações externas para monitorização de parâmetros de qualidade. O DataMiner®, desenvolvido pela Skyline Communications, oferece a capacidade de monitorizar e orquestrar redes de transporte de multimédia bem como de automatizar as suas funcionalidades num vasto conjunto de enquadramentos e ambientes. Tais funcionalidades são oferecidas pelo aparecimento de SDN que permite que se tenha uma visão global de uma rede e que se altere de forma flexível as suas definições através de aplicações. As características de redes deste tipo contrastam fortemente com as redes tradicionais marcadas pela sua rigidez, estaticidade e dificuldade de expansão. Uma área que beneficia bastante com a visão global de redes oferecida pela tecnologia de SDN é a otimização do transporte de dados. Desta forma, uma rede consegue transportar mais dados de forma eficiente através do balanceamento da carga a que é submetida pelas diferentes ligações entre elementos e caminhos que conectam pontos de entrada e saída da mesma, atingindo altos níveis de desempenho. A presente dissertação surge da intenção da Skyline de otimizar o seu algoritmo de encaminhamento através da exploração de métodos alternativos introduzidos pela tecnologia de SDN. Tanto métodos baseados em otimização do custo de ligações da rede como em aprendizagem automática são avaliados como possíveis soluções para o problema proposto e diversas simulações são conduzidas para as comparar e averiguar o seu impacto no desempenho de redes de transporte de dados multimédia

Optimization in Telecommunication Networks

Network design and network synthesis have been the classical optimization problems intelecommunication for a long time. In the recent past, there have been many technologicaldevelopments such as digitization of information, optical networks, internet, and wirelessnetworks. These developments have led to a series of new optimization problems. Thismanuscript gives an overview of the developments in solving both classical and moderntelecom optimization problems.We start with a short historical overview of the technological developments. Then,the classical (still actual) network design and synthesis problems are described with anemphasis on the latest developments on modelling and solving them. Classical results suchas Menger’s disjoint paths theorem, and Ford-Fulkerson’s max-flow-min-cut theorem, butalso Gomory-Hu trees and the Okamura-Seymour cut-condition, will be related to themodels described. Finally, we describe recent optimization problems such as routing andwavelength assignment, and grooming in optical networks.operations research and management science;

Analysis of adaptive algorithms for an integrated communication network

Techniques were examined that trade communication bandwidth for decreased transmission delays. When the network is lightly used, these schemes attempt to use additional network resources to decrease communication delays. As the network utilization rises, the schemes degrade gracefully, still providing service but with minimal use of the network. Because the schemes use a combination of circuit and packet switching, they should respond to variations in the types and amounts of network traffic. Also, a combination of circuit and packet switching to support the widely varying traffic demands imposed on an integrated network was investigated. The packet switched component is best suited to bursty traffic where some delays in delivery are acceptable. The circuit switched component is reserved for traffic that must meet real time constraints. Selected packet routing algorithms that might be used in an integrated network were simulated. An integrated traffic places widely varying workload demands on a network. Adaptive algorithms were identified, ones that respond to both the transient and evolutionary changes that arise in integrated networks. A new algorithm was developed, hybrid weighted routing, that adapts to workload changes

Adaptive laser link reconfiguration using constraint propagation

This paper describes Harris AI research performed on the Adaptive Link Reconfiguration (ALR) study for Rome Lab, and focuses on the application of constraint propagation to the problem of link reconfiguration for the proposed space based Strategic Defense System (SDS) Brilliant Pebbles (BP) communications system. According to the concept of operations at the time of the study, laser communications will exist between BP's and to ground entry points. Long-term links typical of RF transmission will not exist. This study addressed an initial implementation of BP's based on the Global Protection Against Limited Strikes (GPALS) SDI mission. The number of satellites and rings studied was representative of this problem. An orbital dynamics program was used to generate line-of-site data for the modeled architecture. This was input into a discrete event simulation implemented in the Harris developed COnstraint Propagation Expert System (COPES) Shell, developed initially on the Rome Lab BM/C3 study. Using a model of the network and several heuristics, the COPES shell was used to develop the Heuristic Adaptive Link Ordering (HALO) Algorithm to rank and order potential laser links according to probability of communication. A reduced set of links based on this ranking would then be used by a routing algorithm to select the next hop. This paper includes an overview of Constraint Propagation as an Artificial Intelligence technique and its embodiment in the COPES shell. It describes the design and implementation of both the simulation of the GPALS BP network and the HALO algorithm in COPES. This is described using a 59 Data Flow Diagram, State Transition Diagrams, and Structured English PDL. It describes a laser communications model and the heuristics involved in rank-ordering the potential communication links. The generation of simulation data is described along with its interface via COPES to the Harris developed View Net graphical tool for visual analysis of communications networks. Conclusions are presented, including a graphical analysis of results depicting the ordered set of links versus the set of all possible links based on the computed Bit Error Rate (BER). Finally, future research is discussed which includes enhancements to the HALO algorithm, network simulation, and the addition of an intelligent routing algorithm for BP