Showing papers on "Static routing published in 1978"

A Basic Dynamic Routing Problem and Diffusion

Abstract: Diffusion theory has sometimes been successful in providing excellent approximate solutions to difficult queueing problems. Here we explore whether such methods can be used to analyze a basic dynamic routing strategy associated with a single idealized node in a data network. We analyze a dynamic routing policy where messages, or packets, that arrive at a certain node are routed to leave the node on the link having the shorter queue. In the model, message or packet arrivals are Poisson and the service time is exponentially distributed. We explore a heavy traffic diffusion method and we also discuss the limitations of an ad hoc approach to applying diffusion. For a node with K outgoing queues we find, under the assumption of heavy traffic, the optimum dynamic strategy, in the sense of minimizing the average delay. When this optimum dynamic strategy is compared to a static strategy where the outgoing traffic is split among the K queues, we find that the average delay for the dynamic system is better by a factor of K .

A Review of the Development and Performance of the ARPANET Routing Algorithm

Abstract: This paper presents a comprehensive review of the ARPANET routing algorithm, from its original implementation to our plans for future modifications. We hope that by collecting this information, and by providing considerable details, we can provide others with a useful reference document concerning some of the practical problems of network algorithm design. Much of the discussion below assumes a basic familiarity with the principles of packet switching, the ARPANET implementation, and some of the relevant terminology, information which can be found, for example, in [4]. Sections 1 and 2 give a brief summary of basic routing concepts and of the original routing algorithm, respectively. The following two sections describe in detail subsequent modifications and the actual implementation currently in use. Section 5 then discusses some problems that have developed over the past few years, as network usage has grown considerably. The final sections outline some explanations for these problems and some mechanisms for improving performance. We are in the process of implementing these and other changes to the routing algorithm.

Validation of algorithms for optimal routing of flow in networks

Abstract: This paper presents computational results relating to solution of convex multicommodity network flow problems by using several recently developed optimization algorithms. These algorithms are based on the ideas of Gallager's method for distributed optimization of delay in data communication networks [1], and gradient projection ideas from nonlinear programming [2], [3]. They can be used both with and without a line search. An important common feature of the algorithms which distinguishes them from other existing methods is that they utilize second derivatives and are geared towards approximating a constrained version of Newton's method. The computational results confirm that the algorithms tend to employ good search directions as well as automatically generate a satisfactory stepsize regardless of the level and pattern of traffic input to the network. This latter advantage is of crucial importance when the algorithms are used for distributed routing of flow in data communication networks where the use of line search is nearly impossible.

A recoverable protocol for loop-free distributed routing

Abstract: An algorithm fQr adaptive routing in data-conmunication networks is presented. The algorithm uses distributed computation, provides loop-fre_ routing for each destination in the network, adapts to changes in network flows and is completely failsafe. The latter means that after arbitrary failures and additions of nodes and links, the network recovers in finite time in the sense of providing routing paths between all physically connected nodes. Proofs of all these properties are provided in a separate paper.

Extension of an Adaptive Distributed Routing Algorithm to Mixed Media Networks

Abstract: By modeling the broadcast portion of a mixed media network as a fully connected point-to-point network with link capacities varying as functions of the traffic rate it is possible to extend an adaptive distributed routing algorithm that was originally developed for point-to-point ground networks. Additional modifications for improved dynamic performance at the satellite interface message processors are also considered.

Extension of an Adaptive Distributed Routing Algorithm to

Abstract: By modeling the broadcast portion of a mixed media network as a fully connected point-to-point network with link capacities varying as functions of the traffic rate it is possible to extend an adaptive distributed routing algorithm that was originally developed for point-to-point ground networks. Additional modifications for improved dynamic performance at the satellite interface message processors are also considered.

A Comparison of Information Policies for Minimum Delay Routing Algorithms

Abstract: The problem of routing in a computer networks is dealt with by separating the information problem and the control problem. Several classes of information policies are examined, and numerical comparisons are made of their performance, using representative values of network parameters. Routing based on the expected values of delay, rather than actual values of delay, is shown to be superior to the other algorithms considered.

A study on message routing and capacity assignment for store-and-forward computer communication networks

Abstract: This thesis considers message routing and channel capacity assignment problems for store-and-forward computer communication networks. In Chaper 1, fundamental aspects of a computer communication network are presented. Furthermore, a review of the previous researches and the problems studied in this thesis are summarized. In Chapter 2, a store-and-forward computer communication network is mathematically modeled as a simple queueing network. Using this model, many results are given later on. Next, the optimum route assignment problem is formulated as a problem finding the optimum route assignment with the minimum total average message delay. Its solution is derived as the optimum route assignment theorem which gives the necessary and sufficient conditions to minimize the total average message delay. Finally, detouring behavior of the optimum route assignment is -compared with that of the equal-delay-principle route assignment, and the difference between them is clarified In Chapter 3, a new adaptive routing procedure based on the optimum route assignment theorem is proposed. And,from simulation results, it is verified that the new procedure is able to select the route on which total message is transmitted by smaller delay than the ARPA procedure. In Chapter 4, the optimum channel capacity assignment problem is formulated, and its solution is obtained as the optimum channel capacity assignment theorem, which gives the necessary and sufficient conditions to minimize the total average message delay in the case

A minimum principle/queueing theory approach to routing in message-switched networks

Abstract: Preliminary results for minimum message-delay routing in message-switched, store-and-forward, data-communication networks are presented using a minimum principle/queueing theory approach. The routing algorithm is a decentralized one which requires only local information. The results are illustrated via a special case, and extensions and problems for future research are discussed.