Showing papers on "Hazy Sighted Link State Routing Protocol published in 1991"

A framework for adaptive routing in multicomputer networks

Abstract: Message-passing concurrent computers, also known as multicomputers, such as the Caltech Cosmic Cube [47] and its commercial descendents, consist of many computing nodes that interact with each other by sending and receiving messages over communication channels between the nodes. The communication networks of the second-generation machines, such as the Symult Series 2010 and the Intel iPSC2 [2], employ an oblivious wormhole-routing technique that guarantees deadlock freedom. The network performance of this highly evolved oblivious technique has reached a limit of being capable of delivering, under random traffic, a stable maximum sustained throughput of ~~45 to 50% of the limit set by the network bisection bandwidth, while maintaining acceptable network latency. This thesis examines the possibility of performing adaptive routing as an approach to further improving upon the performance and reliability of these networks. In an adaptive multipath routing scheme, message trajectories are no longer deterministic, but are continuously perturbed by local message loading. Message packets will tend to follow their shortest-distance routes to destinations in normal traffic loading, but can be detoured to longer but less-loaded routes as local congestion occurs. A simple adaptive cut-through packet-switching framework is described, and a number of fundamental issues concerning the theoretical feasibility of the adaptive approach are studied. Freedom of communication deadlock is achieved by following a coherent channel protocol and by applying voluntary misrouting as needed. Packet deliveries are assured by resolving channel-access conflicts according to a priority assignment. Fairness of network access is assured either by sending round-trip packets or by having each node follow a local injection-synchronization protocol. The performance behavior of the proposed adaptive cut-through framework is studied with stochastic modeling and analysis, as well as through extensive simulation experiments for the 2D and 3D rectilinear networks. Theoretical bounds on various average network-performance metrics are derived for these rectilinear networks. These bounds provide a standard frame of reference for interpreting the performance results. In addition to the potential gain in network performance, the adaptive approach offers the potential for exploiting the inherent path redundancy found in richly connected networks in order to perform fault-tolerant routing. Two convexity-related notions are introduced to characterize the conditions under which our adaptive routing formulation is adequate to provide fault-tolerant routing, with minimal change in routing hardware, The effectiveness of these notions is studied through extensive simulations, The 2D octagonal-mesh network is suggested; this displays excellent fault-tolerant potential under the adaptive routing framework. Both performance and reliability behaviors of the octagonal mesh are studied in detail. A number of

An analysis of deflection routing in multi-dimensional regular mesh networks

Abstract: A Markov Chain based analysis for deflection routing in n-dimensional regular mesh networks is presented. Detailed analyses are given for the 2D mesh, and a generalization to higher dimensions is outlined. Analytic results are shown to agree very closely with simulations. A basic routing scheme in which all packets have equal priority and a priority scheme in which packets with fewer alternative routes are given priority are proposed and analyzed. Results show that the priority scheme gives higher maximum throughput and lower average packet delay than the basic scheme by reducing average deflections under heavy loads. With the priority scheme, the network performance is almost identical to that of the optimal diagonal routing scheme. By doubling the number of links the throughput is always more than doubled. The authors conclude that in the 2D case, bidirectional links are more cost-effective than unidirectional ones assuming the cost is the number of optical transceivers. >

Technology-trial of dynamic traffic routing with 5 minute updates

Abstract: DR5 (dynamic routing with 5-minute updates) is a routing scheme for telephone traffic in which traffic measurements provided by the switches at 5-min intervals are used to define the routing to be followed for the next 5 min. A successful technology-trial of DR5 was conducted in a five-node subnetwork of 1A-ESS switches. The authors describe the DR5 algorithm, the architecture used for its implementation in the technology trial, and the main results of the trial. They also provide the results of economic studies on the potential benefits of DR5 deployment, and they discuss the possible future implementation of dynamic routing as part of the advanced intelligent network (AIN) architecture. The work described considers dynamic routing in the circuit-switched voice network. >

An Expanded Spanning-tree Protocol For Home-oriented Network Management

Abstract: An expanded spanning-tree protocol capable to simultaneous configurations of plural logical spanning-trees is proposed. It configures a set of optimum spanning-trees and offers an optimal routing path to each packet. This protocol should be highly effective for minimizing the possible traffic increase caused by routing packets and for minimizing the transmission lag. Details of the operating algorithm of the bridge are described. Also proposed is a simplified version of this protocol, called the approximate protocol, which can be incorporated in a more compact form and is much easier to apply. The benefits of these proposed protocols are quantitatively evaluated in terms of the reduction of traffic and packet delay compared with the conventional protocol. >

Neural Network Routing for Random Multistage Interconnection Networks

Abstract: A routing scheme that uses a neural network has been developed that can aid in establishing point-to-point communication routes through multistage interconnection networks (MINs). The neural network is a network of the type that was examined by Hopfield (Hopfield, 1984 and 1985). In this work, the problem of establishing routes through random MINs (RMINs) in a shared-memory, distributed computing system is addressed. The performance of the neural network routing scheme is compared to two more traditional approaches - exhaustive search routing and greedy routing. The results suggest that a neural network router may be competitive for certain RMINs.

Multicast routing algorithms for 3-stage Clos ATM switching networks

Abstract: The author investigates the general problem of multicast routing in the three-stage Clos switching network, with point-to-point routing as a special case. An optimal and a heuristic algorithm have been designed and tested. The results show that the heuristic algorithm can find multicast routes that are close to optimal within a response time that is significantly lower than that of the optimal algorithm. Further analysis of the experimental data suggests a hybrid implementation in which the optimal and heuristic algorithms are run in parallel with a set time limit. The algorithms and the discussion provided also apply to other networks, including wide-area communication networks, with a two-hop structure. >

Intelligent routing in large-scale communications networks

Abstract: The authors consider a class of large-scale communication networks with both dynamic adaptive routing and deterministic routing mechanisms and devise efficient routing algorithms for network designs involving multiple types of traffic. Analytical approaches are combined with quasi-simulation methods to evaluate the performance measures for each given design. The design goal for the networks under study comprises multiple objectives and requirements. Modern expert system and artificial intelligence techniques are incorporated into the design methods to meet the objectives in efficient ways. The routing mechanisms will vary depending on the traffic types, and the affected network performance will be discussed. The study is also extended to integrated networks with voice and data traffic. >

A hierarchical scheme for combined access control and routing of circuit-switched traffic in ISDN environments

Abstract: For integrated networks that support circuit-switched traffic classes with varying bandwidth requirements, an efficient integration of the access control and routing functions is important in realizing optimum network performance. A hierarchical scheme for combined access control and routing is presented for realizing the above objective. The hierarchy comprises two levels; at the lower level each network node implements a distributed call routing strategy, while at the higher level a network supervisor implements an access control policy for minimizing the overall blocking probability. The access control problem to be solved at the supervisor level is formulated in an integer programming framework by a partitioning approach which divides the overall network into several distinct subnets, one corresponding to each bandwidth class. For routing the admitted calls within each subnet in an optimal fashion, a distributed minimum loss routing scheme is developed for implementation at the network nodes. Performance evaluation studies showing the superiority of the various control functions developed are presented. >