Showing papers on "Geographic routing published in 1979"

A Failsafe Distributed Routing Protocol

Abstract: An algorithm for constructing and adaptively maintaining routing tables in communication networks is presented. The algorithm can be employed in message as well as circuit switching networks, uses distributed computation, provides routing tables that are loop-free for each destination at all times, adapts to changes in network flows, and is completely failsafe. The latter means that after arbitrary failures and additions, the network recovers in finite time in the sense of providing routing paths between all physically connected nodes. For each destination, the routes are independently updated by an update cycle triggered by the destination.

An overview of the new routing algorithm for the ARPANET

Abstract: The original routing algorithm of the ARPANET, in service for over a decade, has recently been removed from the ARPANET and replaced with a new and different algorithm. Although the new algorithm, like the old, is a distributed, adaptive routing algorithm, it is not similar to the old in any other important respect. In the new algorithm, each node maintains a data base describing the delay on each network line. A shortest-path computation is run in each node which explicitly computes the minimum-delay paths (based on the delay entries in the data base) from that node to all other nodes in the network. The average delay on each network line is measured periodically by the nodes attached to the lines. These measured delays are broadcast to all network nodes, so that all nodes use the same data base for performing their shortest-path computations. The new routing algorithm was extensively tested on the ARPANET before being released. This paper describes the algorithm and summarizes the results of these tests.

Optimal Distributed Routing for Virtual Line-Switched Data Networks

Abstract: An algorithm that provides minimum delay routing in a data communication network using virtual line-switching is presented. The algorithm uses distributed computation in the sense that the nodes of the network update their information in an orderly fashion based on messages received from their neighbors. Receipt of these messages also triggers the various steps of the update and rerouting, so that these operations are performed in appropriate sequencing. For stationary input requirements and fixed topology the algorithm reduces network delay at each step and provides loop-free routing in the network. The method also provides an algorithm for quasi-static routing, when the input flows are slowly changing.

Binary Routing Networks

Abstract: The design of a communications network based on simple routing of packets through the network and suitable for use in local systems is presented. Several network topologies are considered using differing node structures. Generation of routing information is discussed together with flow control. It is shown that high performance is easily obtained and the system drawbacks do not affect the design for local networks.

Dynamic models of shortest path routing algorithms for communication networks with multiple destinations

Abstract: This paper provides analysis and computational results relating to the dynamic behavior of shortest path routing algorithms for store and forward communication networks. A companion paper [1] focuses on networks with a single destination. The present work considers networks with multiple destinations.

A Routing Algorithm for Signal Processing Networks

Abstract: Algorithms are described here which are suitable for control of a distributed network of signal processors which are interconnected with dedicated paths using decentralized routing control. This paper discusses the algorithm used to implement the processing required at the switching node processor, which can be realized with any of several LSI technologies. Although centralized systems are more efficient in terms of hardware, a single failure in the controller may disable the entire network. This distributed network is implemented with a crossbar switch at each node which facilitates the simultaneous utilization of multiple paths in the network. Index Terms-Computer networks, data routing algorithms, digital signal processing, distributed processing, signal processing networks.

A decentralized algorithm for optimal routing in data-communication networks

Abstract: The goal coordination technique of optimization theory for large-scale systems is used to develop a decentralized algorithm for optimal routing in data-communication networks. The algorithm is in two parts of which the first solves the optimal flow assignment problem and the second provides the corresponding optimal routing. All calculations are distributed among the nodes and require information only from adjacent nodes. The results are illustrated via an example and problems for future research are indicated.

Failsafe distributed optimal routing in data-communication networks

Abstract: : Iterative protocols for adaptive routing in line and message switched data communication networks are presented in this thesis. Distributed computation is used in the sense that each node in the network bases all its decisions on control messages received only from its neighbors. Thus, each node in the network determines individually onto which of its outgoing links to send the flow, addressed to a specific destination. The control messages exchanged between neighbors contain information about network connectivity, network congestion and link failures. Loop-free routing for each destination is maintained in the network at all times. Generally, prevention of loops results in saving resources and reduction in delay. In addition, loop-free routing establishes a partial ordering on the set of nodes of the network. The latter property is extensively utilized throughout this work. failsafe and deadlock-free operation of the protocols is guaranteed, meaning that after arbitrary failures and additions of links and nodes, the network recovers in finite time. Recovery means that routing paths are provided between all connected nodes. For stationary input traffic statistics and fixed topology the protocols are optimal. they reduce network delay at each iteration and minimum average delay over all routing assignments is obtained in steady-state.

DYNhUIC MODELS OF SHORTEST PATH mING ALGORITHUS POR C!OHWNICATICN NETWRKS WITH KJLTIPLE DESTINATICNS

Abstract: This paper provides analysis and canputational results relating to the dynamic behavior of shortest path routing algorithms for store and forward comnunication networks. A companion paper 111 focuses on networks with a single destination. The present work considers networks with multiple destinations. which examines the dynamic behavior of shortest path routing algorithms for comnunication networks with a single destination. We examine here the case wh&e there are several destinations. Generally speaking, the results obtained for single destination networks have extensions to the multiple destination case although the analysis is considerably more romplex. Similarly as for single destination algorithms we find that the addition of a bias factor and the presence of an averaging mechanism have a stabilizing effect on dynamic behavior. Our results also suggest that the presence of multiple destinations has a damping effect on the dynamic behavior of the algorithm. Similarly as in [l] we consider a network &el with a continuum of nodes and rely on methods of convergence analysis for discrete-time systems with Euclidean state space. The possibilities for extension of these results to finite node networks

A simulation model for network routing

Abstract: The simulation program described in this paper was devised as a vehicle for the study of communication network routing procedures. It was designed to model the behavior of a wide range of network topologies and routing disciplines. An event driven simulation approach was chosen to minimize program development time and complexity.GASP-IV was selected as the simulation language. The determining factor in choosing the language was the clean interface it presents to FORTRAN. The use of GASP-IV permits utilizing the full power of FORTRAN in describing complex routing algorithms while simultaneously relieving the programmer of the responsibility for such essential housekeeping functions as enqueuing and dequeuing messages, file manipulation and event sequencing.As an application of this simulator, a loop-free distributed adaptive routing algorithm is proposed and analyzed. Simulation results are presented and the effect of the algorithm on overall network performance is examined. In addition to a loop-free property, the algorithm is shown to provide a partial solution to the single path routing problem. Furthermore, a modification to the algorithm is given which precludes message loss, and is shown to be superior in performance to current update algorithms (PUA).