Showing papers on "Hazy Sighted Link State Routing Protocol published in 1997"

A highly adaptive distributed routing algorithm for mobile wireless networks

Abstract: We present a new distributed routing protocol for mobile, multihop, wireless networks. The protocol is one of a family of protocols which we term "link reversal" algorithms. The protocol's reaction is structured as a temporally-ordered sequence of diffusing computations; each computation consisting of a sequence of directed link reversals. The protocol is highly adaptive, efficient and scalable; being best-suited for use in large, dense, mobile networks. In these networks, the protocol's reaction to link failures typically involves only a localized "single pass" of the distributed algorithm. This capability is unique among protocols which are stable in the face of network partitions, and results in the protocol's high degree of adaptivity. This desirable behavior is achieved through the novel use of a "physical or logical clock" to establish the "temporal order" of topological change events which is used to structure (or order) the algorithm's reaction to topological changes. We refer to the protocol as the temporally-ordered routing algorithm (TORA).

Associativity-Based Routing for Ad Hoc Mobile Networks

Abstract: This paper presents a new, simple and bandwidth-efficient distributed routing protocol to support mobile computing in a conference size ad-hoc mobile network environment. Unlike the conventional approaches such as link-state and distance-vector distributed routing algorithms, our protocol does not attempt to consistently maintain routing information in every node. In an ad-hoc mobile network where mobile hosts (MHs) are acting as routers and where routes are made inconsistent by MHs‘ movement, we employ an associativity-based routing scheme where a route is selected based on nodes having associativity states that imply periods of stability. In this manner, the routes selected are likely to be long-lived and hence there is no need to restart frequently, resulting in higher attainable throughput. Route requests are broadcast on a per need basis. The association property also allows the integration of ad-hoc routing into a BS-oriented Wireless LAN (WLAN) environment, providing the fault tolerance in times of base stations (BSs) failures. To discover shorter routes and to shorten the route recovery time when the association property is violated, the localised-query and quick-abort mechanisms are respectively incorporated into the protocol. To further increase cell capacity and lower transmission power requirements, a dynamic cell size adjustment scheme is introduced. The protocol is free from loops, deadlock and packet duplicates and has scalable memory requirements. Simulation results obtained reveal that shorter and better routes can be discovered during route re-constructions.

A new routing protocol for the reconfigurable wireless networks

Abstract: We propose a new routing protocol, the Zone Routing Protocol (ZRP), for the reconfigurable wireless networks, a large scale, highly mobile ad-hoc networking environment. The novelty of the ZRP protocol is that it is applicable to large flat-routed networks. Furthermore, through the use of the zone radius parameter, the scheme exhibits the adjustable hybrid behavior of proactive and reactive routing schemes. We evaluate the performance of the protocol, showing the reduction in the number of control messages, as compared with other reactive schemes, such as flooding.

A cluster-based approach for routing in dynamic networks

Abstract: The design and analysis of routing protocols is an important issue in dynamic networks such as packet radio and ad-hoc wireless networks Most conventional protocols exhibit their least desirable behavior for highly dynamic interconnection topologies We propose a new methodology for routing and topology information maintenance in dynamic networks The basic idea behind the protocol is to divide the graph into a number of overlapping clusters A change in the network topology corresponds to a change in cluster membership We present algorithms for creation of clusters, as well as algorithms to maintain them in the presence of various network events Compared to existing and conventional routing protocols, the proposed cluster-based approach incurs lower overhead during topology updates and also has quicker reconvergence The effectiveness of this approach also lies in the fact that existing routing protocols can be directly applied to the network --- replacing the nodes by clusters

QoS routing mechanisms and OSPF extensions

Abstract: This paper presents and discusses path selection algorithms to support QoS routes in IP networks. The work is carried out in the context of extensions to the OSPF protocol, and the initial focus is on unicast flows, although some of the proposed extensions are also applicable to multicast flows. We first review the metrics required to support QoS, and then present and compare several path selection algorithms, which represent different trade-offs between accuracy and computational complexity. We also describe and discuss the associated link advertisement mechanisms, and investigate some options in balancing the requirements for accurate and timely information with the associated control overhead. The overall goal of this study is to identify a framework and possible approaches to allow deployment of QoS routing capabilities with the minimum possible impact to the existing routing infrastructure.

Ants and reinforcement learning: a case study in routing in dynamic networks

Abstract: We investigate two new distributed routing algorithms for data networks based on simple biological "ants" that explore the network and rapidly learn good routes, using a novel variation of reinforcement learning. These two algorithms are fully adaptive to topology changes and changes in link costs in the network, and have space and computational overheads that are competitive with traditional packet routing algorithms: although they can generate more routing traffic when the rate of failures in a network is low, they perform much better under higher failure rates. Both algorithms are more resilient than traditional algorithms, in the sense that random corruption of routing state has limited impact on the computation of paths. We present convergence theorems for both of our algorithms drawing on the theory of non-stationary and stationary discrete-time Markov chains over the reals. We present an extensive empirical evaluation of our algorithms on a simulator that is widely used in the computer networks community for validating and testing protocols. We present comparative results on data delivery performance, aggregate routing traffic (algorithm overhead), as well as the degree of resilience for our new algorithms and two traditional routing algorithms in current use. We also show that the performance of our algorithms scale well with increase in network size-using a realistic topology.

A system and traffic dependent adaptive routing algorithm for ad hoc networks

Abstract: An ad hoc network consists of a number of mobile hosts who communicate with each other over a wireless channel without any centralized control. The basic problem is to obtain a distributed routing scheme so that under the network connectivity assumption any mobile host can transmit/receive data from any other host in the network. In this paper we propose a new routing algorithm for ad hoc networks. The proposed algorithm uses a more appropriate distance measure given by the expected delay along a path, instead of the number of hops used in most of the existing algorithms. This metric allows the algorithm to adapt to changes not only in the topology of the network, but also in the traffic intensity. The algorithm uses a novel technique for estimating the path delays without requiring the links to be bidirectional or the clocks at the nodes in the network to be synchronized. The proposed algorithm is able to perform both reliable and good routing with low communication overhead and computational requirements.

An experimental study of insider attacks for OSPF routing protocol

Abstract: It is critical to protect the network infrastructure (e.g., network routing and management protocols) against security intrusions, yet dealing with insider attacks are probably one of the most challenging research problems in network security. We study the security threats, especially internal/insider threats, for the standardized routing protocol OSPF. In OSPF, a group of routers collaborate, exchange routing information, and forward packets for each other. If one (and maybe more than one) router is evil or compromised, how can this router damage the whole network? In this paper, we analyze OSPF and identify its strengths and weakness under various insider attacks. Furthermore, to confirm our analysis, we have implemented and experimented one attack, the max sequence number attack, on our OSPF routing testbed. Our attack is very successful against two independently developed router products as it will block routing updates for 60 minutes by simply injecting one bad OSPF protocol data unit.

A survey and comparison of wormhole routing techniques in a mesh networks

Abstract: The growing demand for high processing power in various scientific and engineering applications has made multiprocessing architectures increasingly popular. These multiprocessing systems consist of processing elements or nodes which are connected together by interconnection networks in various topologies. One of the design methodologies used for parallel machines has fed to the development of distributed memory message-passing concurrent computers, commonly known as multicomputers. They consist of many processing nodes that interact by sending messages (containing both data and synchronization information) over a communication link, between nodes. Thus, efficient communication in multicomputers is one of the important research areas in parallel computing today, and it depends on the underlying scheme for routing. For this reason it is essential to know which routing techniques are suitable and practical. Although an extremely wide number of routing algorithms have been proposed and implemented in hardware and software, it is difficult for the designer of a multicomputer to choose the best routing algorithm given a particular architectural configuration. In an attempt to overcome this difficulty, we present a survey and comparison of wormhole routing techniques in mesh interconnection networks. The mesh topology is important because of its scalability. Moreover, it has already been implemented in many commercial multicomputers.

A new hierarchical routing protocol for dynamic multihop wireless networks

Abstract: The routing techniques used in conventional packet radio networks are not suitable for dynamic multihop wireless networks because of their unique architecture. In this paper a new hierarchical multihop routing algorithm is introduced which balances the cost of location-update and path-finding operations by partitioning the terminals and mobile base stations to produce a virtual topology. Based on the virtual topology each network entity stores a fraction of the network topology information and maintains the routing efficiency. Finally, the performance of the hierarchical multihop routing algorithm is investigated through simulations.

System for routing computer network

Abstract: A routing system transmits and receives routing information in a computer network having computers of a first kind which support a routing protocol on a connectionless network protocol and computers of a second kind which do not support the routing protocol that is supported by the computers of the first kind, the computers of the first and second kinds being present in the same connectionless network. One of the computers of the first kind establishes a connection in a transport layer to another computer of the first kind through a computer of the second kind. Thereafter, data to be transmitted and received according to the routing protocol to a destination computer through the computer of the second kind are transmitted and receiving using the connection in the transport layer.

A dynamic routing protocol for broadband networks

Abstract: An efficient dynamic routing protocol is necessary for future broadband networks where a variety of services with different characteristics and QoS requirements are integrated. The main components of a dynamic routing protocol are the exchange of topology state information, the routing algorithm and the routing decision. The exchange of topology state information helps in keeping the network nodes updated on the network status and hence making the correct routing decision. The routing algorithm is responsible for computing the best paths for different source-destination pairs. The routing decision taken at a node decides the path to be followed by a certain call. Different alternatives are possible in the design of each of these components leading to different scenarios for the routing protocol. These different scenarios are examined based on both analytical and/or simulation results and the one with the best results in terms of efficiency as well as various performance measures is presented. The simulation is carried out over a practical network topology; the NSFNET.

Analysis methodology for simulation of distributed adaptive routing systems

Abstract: In network simulations, complex dynamical behavior is Previous analysis has identified limitations associated with Markov Chain Models and has established a need for the analysis of network dynamics through bound-queue/minimum-interarrival-time simulation models. In network simulations, complex dynamical behavior is observed even for simplistic stationary offered loads. An important contributor to the complexity of the network dynamics is the routing system. When a network consists of a large number of nodes, a routing system is applied in order to route traffic in an efficient manner between the nodes. The routing system has an important effect on the resulting network dynamics. This paper will discuss the complex dynamical behavior observed in networks controlled by distributed adaptive routing systems. This methodology can be applied during stability analyses of routing systems and is useful in system-level simulation verification.

Hybrid routing in dynamic networks

Abstract: In mobile radio communication networks the distribution of traffic loads and network topologies may vary from nearly static to very dynamic. This dynamic behaviour may vary both in space and in time. Since routing algorithms tend to be well suited to specific networking environments, it is very difficult to select a single routing algorithm that is most appropriate for a given network, if the network is subjected to varying degrees of dynamic behaviour. This paper proposes a routing strategy that smoothly adapts to changing network conditions by combining two distinct routing principles into a single hybrid routing procedure. The hybrid routing strategy exhibits a smooth change from shortest path routing to constrained flooding, as the behaviour of the network (or regions within) changes from quasi-static to very dynamic.

A distributed optimal routing strategy based on an estimation of the OD matrix

Abstract: This paper presents a distributed optimal routing strategy that is based on an estimation of the OD (origin-destination) matrix. This routing strategy may be employed in packet-switched networks. In the most common form of distributed routing, every node acts autonomously, distributing its link delay information to all other network nodes and periodic or aperiodic computing its own routing table based upon the link delays information obtained from other network nodes. The optimal routing assumes that the OD matrix is known. In order to avoid the transportation of the OD matrix through the communication network, it is estimated based on the link delays, the transit flows and the prior OD matrix. The represented routing strategy involves a computationally intensive iterative procedure, and therefore within large networks, this routing strategy becomes impractical. In these networks, during normal operation of the network, without changes in the network topology, a primitive routing algorithm such as a distributed Frank-Wolfe with fixed stepsize might be used. In addition, every node estimates the OD matrix. Then in the case of changes in the network topology, the estimated OD matrix is used to compute the routing tables. A further application of this strategy is within the network performance monitoring.