Showing papers on "Routing table published in 1981"

Apparatus using a decision table for routing data among terminals and a host system

Abstract: A router module controls interfaces to (a) terminals, (b) communications to a host system, and (c) a permanent storage device like a digital cassette. The router module utilizes routing logic including a decision table to effect the routing through the interfaces named. The terminals include data entry terminals and a printer module and the router module enables several data entry terminals to utilize the printer module. The router module is located on a substrate which can be mounted in one of the data entry terminals to utilize the associated power supply.

Provably Good Channel Routing Algorithms

Abstract: In this paper we present three new two-layer channel routing algorithms that are provably good in that they never require more than 2d-1 horizontal tracks where d is the channel density, when each net connects just two terminals. To achieve this result, we use a slightly relaxed (but still realistic) wiring model in which wires may run on top of each other for short distances as long as they are on different layers. Two of our algorithms will never use such a “parallel run” of length greater than 2d-1 and our third algorithm will require overlap only at jog points or cross points. Since in this wiring model at least d/2 horizontal tracks are required, these algorithms produce a routing requiring no more than four times the best possible number of horizontal tracks. The second algorithm also has the property that it uses uses at most 4n contacts, where n is the number of nets being connected.

Advances in Verifiable Fail-Safe Routing Procedures

Abstract: Two new versions of a distributed protocol for establishing and maintaining loop-free routing tables for communication networks with changing topology are presented. The protocols here possess significant advantages over previous versions in terms of complexity of the node algorithm and of the validation procedure, as well as the communication and storage needs. In addition, we present a procedure for establishing new and disrupted calls in a virtual or physical circuit-switched network, and for canceling existing calls, such that each call is loop-free and is established according to the routing tables provided by the protocol.

A Technique for Adaptive Routing in Networks

Abstract: A two-level adaptive routing scheme for packet-switched computer communication networks is proposed and investigated. The first level is quasi-static and based on the global network status. The second level is dynamic with decisions being made at each node in an attempt to obtain the savings in average delay predicted by a multiserver model of the node. Simulations confirm the predicted improvement.

Optimal Routing in Rectilinear Channels

Abstract: Programs for integrated circuit layout typically have two phases: placement and routing. The router should produce as efficient a layout as possible, but of course the quality of the routing depends heavily on the quality of the placement. On the other hand, the placement procedure would like to know how good a routing it can expect without actually routing the wires. This paper presents fast algorithms for optimal routing and for accurately estimating the area cost of such routings without actually laying them out.

An Evaluation of Local Path ID Swapping in Computer Networks

Abstract: This paper analyzes a method for identifying end-to-end connections in computer networks which is designed to provide reductions in the sizes of the packet headers and routing tables stored in the nodes. The method, known as Local Path ID Swapping, uses a shortened connection identifier, called the LPID, in the message headers and routing tables. In general, the LPID field is swapped in the message header from node to node along the path of the route. Some analytical results are presented for evaluating the important tradeoffs involved in LPID swapping. Most notable is the tradeoff between the size of the LPID field and the number of connections which can be defined in the network.

Internetworking in the Military Environment

Abstract: : The increasing requirement for data communications in the military environment and the heterogeneous nature of the network technologies and protocols involved are highlighted. The main section of the paper discusses how the design of a military internet architecture is influenced by the military requirements especially that of survivability. Comparison with the civilian PTT approach to internetworking shows that while there are economic advantages to using civilian international standards where possible, these standards do not satisfy the military requirements. In particular the strategies for routing in a heavily changed network environment and addressing hosts that migrate from one network to another must form an integral part of the overall architectural design. This results in gateways whose routing tables have a finer degrees of detail of the internet topology than is usually required but which do not contain connection orientated information. (Author)

A Failsafe Distributed Protocol for Minimum Delay Routing

Abstract: Previous distributed routing protocols in data-communication networks that achieve minimum average delay are extended to take into consideration topological changes in the network.

TWIGY A Topological Algorithm Based Routing System

Abstract: A two-level approach to routing is described, in which a multi-layer printed circuit board routing problem is broken down into a set of single-layer ones. A topological transformation is then applied to accomplish single-layer routing. A solution found for each layer by a search in this new domain is then translated back into physical space by means of a deterministic drawing algorithm. The algorithms are independent of specific technological parameters, affording their use on a variety of board routing grids, pad diameters and wire sizes.

Delay Analysis of Broadcast Routing in Packet-Switching Networks

Abstract: Broadcast addressing is the capability to send a packet from a source node to all other nodes in the network. Store-and-forward, packet-switching networks are not inherently designed to carry broadcast packets, and broadcasting has to be implemented by some sort of routing algorithm. In this paper, the source based forwarding algorithm is considered. With this algorithm, a spanning tree is defined for each node, and broadcast packets are sent along the branches of these trees. Approximation methods are presented to obtain a lower bound and estimates of the mean broadcast time. The accuracy of these methods is evaluated by comparison with simulation.

A distributed minimum hop routing algorithm

Abstract: A two-part distributed algorithm for minimum hop routing in message-switched networks subject to end-to-end average message delay constraints is developed. The first part of the algorithm provides for unconstrained minimum hop routing, while the second corrects this routing to satisfy the delay constraints. Both parts are implemented nodewise via low-order linear programs wherein the information exchange required for each node to carry out its computations involves only adjacent neighbor nodes. The algorithm is illustrated via an example of an 8- node, 14-link network with 7 commodities, and directions for future research to enhance present results are indicated.

Aiming at a General Routing Strategy

Abstract: A general method for automatic routing, based on a channel splitting approach, is presented. A weighted graph depicting multilayer partitions and allowing expected channel occupancy estimation is introduced. Problems and algorithms related to the detailed routing phase are briefly reviewed.

A Preprocessor for Channel Routing

Abstract: This paper presents a "preprocessor" which separates a channel routing problem into two subproblems. One is a specialized channel routing problem where no two nodes of two different nets are of the same y-grid position. The other is a problem of connecting pairs of nodes where each pair of nodes has a path reserved for it. The use of a "preprocessor" in channel routing [5] is justified by the comparison of routing results.

Adaptive routing in large communication networks: Probabilistic study

Abstract: A network model is presented and conditions for stochastic stability of the network system are given. For adaptation algorithms which change the routing probabilities slowly (small stepsize), expressions for steady-state variances are derived; usimg these, guidelines for the selection of algorithm parameters are discussed.