Showing papers on "Geographic routing published in 1989"

Message routing system for shared communication media networks

Abstract: A plurality of disparate communication network systems communicate with each other through the use of different physical media protocols. Each of the systems has at least one input and one output. A message routing system couples a transmitter at any one system input to a receiver at any other system output using a message format that is structure independent of the location of the receiver in the system. Each receiver/transmitter device coupled to any one system input has a unique, fixed and unchangeable identification code regardless of the communication network system to which it is connected. To couple a message from any one receiver/transmitter device to a second receiver/transmitter device at an unknown location within the communication network system, a message format is transmitted from the sending location containing the fixed, unique identification code of the receiving station. A routing system having a plurality of intermediate routing devices receives the message format and couples it to the receiving station at the unknown location using only the fixed, unique identification codes of the transmitting and receiving stations and the addresses of the intermediate routing devices for determining routing.

Method for routing packets in a packet communication network

Abstract: A packet network routing method and system based on geographic coordinate identifiers is described. Each node in a network is uniquely identified by absolute geographical coordinates or by a code indicating absolute location in an external coordinate-based reference system (node coordinates), and such absolute geographical coordinates or the equivalent are employed as part of a packet identifier for each packet generated for use in making routing decisions. The node coordinates of a local node and its neighboring nodes and the packet coordinates are used by means at each node through which a packet is routed for determining a desired forwarding route of a data packet. The routing may be prioritized according to preselected criteria, preferably achieving maximum forward progress using the least amount of power. The packet routing protocol according to the invention requires no routing directory or table to perform data routing. Each node of the network collects in a table or is otherwise provided with information about the quality of communication between itself and its neighboring nodes. When a data packet has been received at a node, it is routed further through the network based on criteria derived from the history of communication between the local node and its neighbors.

High Performance Communications In Processor Networks

Abstract: In order to provide an arbitrary and fully dynamic connectivity in a network of processors, transport mechanisms must be implemented, which provide the propagation of data from processor to processor, based on addresses contained within a packet of data. Such data transport mechanisms must satisfy a number of requirements - deadlock and livelock freedom, good hot-spot performance, high throughput and low latency. This paper proposes a solution to these problems, which allows deadlock free, adaptive, high throughput packet routing to be implemented on networks of processors. Examples are given which illustrate the technique for 2-D array and toroidal networks. An implementation of this scheme on arrays of transputers is described. The scheme also serves as a basis for a very low latency routing strategy named the mad postman, a detailed implementation of which is described here as well.

Method and apparatus for providing a local area network bridge

Abstract: A communication bridge interconnecting two or more local area networks. Input buffers forward packet headers of received data packets through to a routing engine. The routing engine contains one or more routing tables each having a plurality of table locations containing table data in the form of station addresses and routing data. The table is accessed by applying a hashing algorithm to a received destination address contained in the data packet to determine the table location and then checking that the station address retrieved from the table location corresponds with the destination address in the received data packet.

An optimal shortest-path routing policy for network computers with regular mesh-connected topologies

Abstract: A probabilistic routing policy, the Z/sup 2/ (zigzag) routing policy, is presented within the class of nonadaptive, shortest-path routing policies for regular mesh-connected topologies such as n-dimensional toroids and hypercubes. The focus of the research is routing in networks of computers in a distributed computing environment, where constituent subcomputers are organized in a mesh-connected topology and communication among individual computers takes places by some form of message exchange. The authors prove the optimality of this policy with respect to two criteria: (1) maximizing the probability of reaching the destination from a given source without delays at intermediate nodes; and (2) minimizing the expected lifetime of a message. >

The Arc Oriented Location Routing Problem

Abstract: The location routing problem is concerned with locating depots and creating routes to service customers. In particular, location-allocation-routing (LAR) algorithms are designed to locate facilities, allocate customers to facilities and design the routes through these customers. In the literature, the typical location routing problem is a node oriented problem, where depots and customers are all represented by nodes and the routing is a node routing problem. In this paper, an Arc Oriented Location Routing Problem (AOLRP) is described, where the customers to be serviced are represented by arcs. Therefore, the allocation of customers to depots is an arc oriented problem as well as the resulting routing problem. An algorithm is presented for solving the AOLRP and computational results are given regarding parameter settings and performance of this algorithm.

Distributed split flow routing mechanism for multi-node packet switching communication network

Abstract: Routing variables for near optimally controlling the distributed flow of information signals from a node s over a multinode communication network to a destination node d are generated in accordance with a prescribed heuristic among network path delays. A prescribed routing variable value (e.g. zero) is assigned to each route to a node n, representing that that node is not to be used to route information signals from node s to node d, for any node of the network that either is not directly connected to node s, has not established a connection path to a destination node d, or is using node s as part of its communication path to destination node d. The path delays from node s to neighboring nodes n are measured and a measurment of the path delay from node s to destination node d is obtained. In addition periodically updated measurements of the path delays from neighboring nodes n to destination node d are received. For each neighboring node that may be used to route traffic, its associated routing variable is generated in accordance with the heuristic among the path delays. The path delay from node s to node d is then updated in accordance with a weighted sum of the routing variables and transmitted to neighboring nodes.

Upper and lower bounds for routing schemes in dynamic networks

Abstract: An algorithm and two lower bounds are presented for the problem of constructing and maintaining routing schemes in dynamic networks. The algorithm distributively assigns addresses to nodes and constructs routing tables in a dynamically growing tree. The resulting scheme routes data messages over the shortest path between any source and destination, assigns addresses of O(log/sup 2/n) bits to each node, and uses in its routing table O(log/sup 3/n) bits of memory per incident link, where n is the final number of nodes in the tree. The amortized communication cost of the algorithm is O(log n) messages per node. Also given are two lower bounds on the tradeoff between the quality of routing schemes (i.e. their stretch factor) and their amortized communication cost in general dynamic networks. >

A distributed routing algorithm for mobile radio networks

Abstract: The authors present a distributed routing protocol intended for use in networks where the rate of topological change is not so fast as to make 'flooding' the only possible routing method but not so slow as to make one of the existing protocols for a static topology applicable. The routing algorithm adapts asynchronously in a distributed fashion to arbitrary changes in topology in the absence of global topological knowledge. The protocol maintains a set of loop-free routes to each destination from any node that desires a route. The protocol's performance, measured in terms of end-to-end packet delay and throughput, is compared with that of pure flooding and an alternative algorithm that is well suited to the medium-rate topological change environment envisioned here. The results show that, when the rate of topological change becomes very high, flooding is preferable to the other alternatives. For lower rate of change, it appears that, when the effects of channel access are accounted for, the performance of the new algorithm is encouraging in that it has been generally superior to that of the alternative protocols. >

Robust algorithms for packet routing in a mesh

Abstract: This paper considers the problem of permutation packet routing on a √n×√n mesh-connected array of processors. Each node in the array is assumed to be independently faulty with a probability bounded above by a valuep. This paper gives a routing algorithm which, ifp⩽ 0.29, will with very high probability route every packet that can be routed inO(√n logn) steps with queue lengths that areO(log2n). Extensions to higher-dimensional meshes are given.

Method for accessing data in a table and its application to the routing of data between remote stations

Abstract: The present invention relates to the accessing data in tables and its application to apparatus for providing a communication bridge interconnecting two or more local area networks (LAN). A LAN (1) is connected to another LAN 2 by means of a bridge generally designated by the numeral (3). Input buffers (11, 21) forward packet headers of received data packets through to a routing engine (5). The routing engine (5) contains one or more routing tables each having a plurality of table locations containing table data in the form of station addresses and routing data. The table is accessed by applying a hashing algorithm to a received destination address contained in the data packet to determine the table location and then checking that the station address retrieved from the table location corresponds with the destination address in the received data packet. If the table location is empty or the destination address does not match the station address, the data packet is forwarded to all interconnected LANs. Otherwise, the data packet is forwarded according to the retrieved routing data. Embodiments are described wherein the table locations are over-written by applying the hashing algorithm to the source address of a received data packet and writing in at the resultant table location the source address and routing information of the received data packet. A time stamp can also be written at this time so that obsolete data entries are not employed for routing.

Analysis and design of a highly reliable transport architecture for ISDN frame-relay networks

Abstract: The authors explore control strategies in the design of a high-performance transport architecture for integrated services digital network (ISDN) frame-relay networks. For real-time congestion control, buffer management, priority queueing, adaptive windowing, and selective frame, discard policies are described that can effectively maximize network efficiency while preventing unfair usage of shared network resources. Virtual-circuit routing strategies are proposed that ensure an efficient distribution of traffic loads across the network despite variations in traffic patterns and topology changes. It is shown that source routing provides significant performance benefits over link-by-link routing, particularly in large networks that are not so densely connected. Routing table update and call acceptance mechanisms are described that provide for efficient bandwidth management in the network. Fault-tolerant strategies are described that include fast failure detection and local reroute. These strategies are capable of restoring affected virtual circuits in less than 10 s, which is adequate for session maintenance under most application scenarios. >

Deadlock-free message routing in multicomputer networks

Abstract: The execution of a concurrent computation by a network of processors requires a routing algorithm that is deadlock free. Many routing algorithms proposed for processor networks have the potential of deadlock due to the cyclic topology of the network. In this paper we first formalize the concept of message routing. Next, we show a method by which a deadlock-free routing algorithm can be constructed out of a given routing algorithm. Finally the method is illustrated by constructing deadlock-free routing algorithms for cartesian product processor networks.

Autonomous routing scheme for large scale network based on neural processing

Abstract: The authors discuss an autonomous routing scheme (called Holonic Routing) for large-scale networks that uses the principle of neural networks. In this scheme each node computes the optimal route whenever it tries to transmit a packet; thus the network can always maintain a balanced load, providing maximum transmission capacity in response to changes in traffic and topology. Because the routing procedure is packet by packet, even if a failure occurs in transit the packet will automatically be routed to avoid failed parts. Thus, a reliable nonstop network can be easily constructed using this scheme. The scheme is especially suitable for multimedia networks where large capacity and high reliability are needed. >

A routing architecture for very large networks undergoing rapid reconfiguration

Abstract: A routing architecture is described for very large communications networks with greater than 10,000 routing nodes and 100,000 end nodes. This architecture, called the Traveler Architecture, is designed to be independent of network configuration and to be robust even under conditions of rapid reconfiguration. Traveler is an extension of the ISO routing protocols. The Traveler architecture is designed to work with traffic characteristic of existing large networks, such as the Internet. While Traveler does not require a particular routing algorithm, it is designed to work in conjunction with families of distributed routing algorithms. Because Traveler is based on the paradigm of a human traveler, it attempts to use non-deterministic and heuristic methods rather than purely algorithmic methods to determine high quality routes between two points. Traveler builds on the Landmark and Area routing architectures.

Routing in multiple domain networks

Abstract: The problem of management and control in a large and, for simplicity, homogeneous packet-switched network is investigated. In particular, routing is considered as an important function of network management. The network consists of several individually controlled domains interconnected via gateway links. Each domain is controlled by its own network control center, while the overall network performance is managed by the integrated network control center. Each center has only a portion of the information required for global routing. The impact of the reduced information available at each center on network performance is investigated. A general approach to designing a hierarchical algorithm for routing in multi-domain networks is presented. A heuristic procedure suitable for packet-switched networks is proposed. An example of the algorithm is shown. Its performance is compared against a lower bound to the network performance. >

Performance evaluation of adaptive traffic routing in a metropolitan network: a case study

Abstract: A performance analysis of adaptive traffic in the telephone network of Marseilles, France is presented. The authors give the main reasons for introducing flexible routing-especially, state-dependent routing-in modern telephone networks. They present the Marseilles network under study and briefly describe the routing algorithm and the network design method used. They consider a number of scenarios ranging from traffic overloads to network failures in order to evaluate the robustness and performance of the adaptively routed network. Simulations that emphasize the role of state-dependent routing in network efficiency are presented and analyzed. In some specific cases, the state-dependent routing is complemented with predictive control actions to limit low priority or overflow traffic. This results in an improved grade of service. It is concluded that adaptive traffic routing can cope with a large range of network conditions, such as traffic overloads and equipment failures. >

An Algorithm for Joint Routing and Scheduling in Radio Networks

Abstract: The problem of evacuation in minimum time of a PRN is considered. We decompose the problem into a scheduling problem for one hop neighbor transmissions and a routing problem. We propose an iterative algorithm for the routing problem. Finally we view the routing problem as a sequence of maxflow problems.

Acknowledgment-based broadband switching architecture

Abstract: A simple architecture for broadband switching based on a multistage interconnection network without internal buffers is proposed. An acknowledgment-based mechanism to manage contention situations that arise in the routing network is provided. The proposed architecture can be used with different kinds of routing networks to obtain a compromise between performance and complexity. For this purpose, performance comparisons between some significant examples of routing networks are also presented.

Design analysis of nonhierarchical node-by-node routing virtual circuit networks

Abstract: The author describes a novel approach to the design of node-by-node routing virtual circuit data networks. A major challenge in the design of such networks is to ensure that the network has loop-free alternate routing. The approach explicitly integrates the loop-free alternate routing requirements into the network design process and produces loop-free cost optimized networks. This is achieved by identifying a topology which supports loop-free alternate routing. This topology is optimal in the sense of achieving a prescribed level of network connectivity with the fewest possible links. This topology have several desirable routing properties, based on which a simple loop-free alternate routing scheme has been developed. Further, by solving an optimization problem, it is possible to find the optimal connectivity between nodes that minimizes the total link length. This leads to a significant reduction in network cost. Two methods for solving this optimization problem have been developed. >

A simple table-free distributed routing algorithm for 802.6

Abstract: The authors propose a simple table-free routing technique for the IEEE 802.6 Distributed Queue Dual Bus (DQDB). It offers the simplicity of high-speed packet switching, such as Batcher-Bayan, techniques to metropolitan-area networks. As in high-speed packet switching networks, it consists of a number of stages. A so-called self-routing technique routes a packet from one end to the other without table processing. By checking only one bit in the routing tag of a message at each stage, a switch knows to which switch the message is to be routed in the next stage. The proposed technique is similar to the knockout switch. However, instead of performing switching in a small area, it covers a much wider (metropolitan) area. Therefore, the technique becomes distributed. The proposed routing technique can be extended to cover a service of point-to-multipoint communications, something which is essential for B-ISDN, while maintaining much of its simplicity. Various issues of sequential delivery, replication, and label management are addressed. A novel technique for simplifying topologies is presented. >

A routing scheme for hierarchically structured LAN/WAN networks

Abstract: The authors propose a routing scheme for multiorganizational networks structured hierarchically in a two-level LAN/WAN (local-area network/wide-area network) configuration. The targeted networks, besides being hierarchical, are small in size than the public internets. These two characteristics play a key role in identifying suitable routing mechanisms. The authors propose a simple area routing algorithm for the two-level LAN/WAN network. Its main features consist of a decentralized interarea routing algorithm, with centralized routing functions within areas for interarea routing only. The routing mechanism does not interfere with the operation of the local subnets. The operation of the routing centers is fairly simple and can easily be duplicated in all the gateway nodes for reliability. The gateway routing protocol is based on source routing and is very simple to implement, consisting of only a mapping function. It involves very little processing overhead at the transit gateways. >

Distributed routing algorithm performance in hostile environments

Abstract: The authors consider the problem of optimum shortest-path routing in a communications network consisting of multiple nodes and links located in a hostile environment. The robustness of the routing algorithm to node or link failures is of interest here. The type of environment suggests that use of distributed or noncentralized algorithms in which convergence of the network to the shortest-path routing tables is of primary concern. Two distributed routing algorithms (that of L.R. Ford, Jr., and D.R. Fulkerson, Flows in Networks. Princeton, NJ: Princeton Univ. Press, 1962, and that of P.M. Merlin and S. Segall, IEEE Trans. Commun. vol. COM-27, 1280-7, Sept. 1979) are examined in terms of speed and overhead. Computer simulations measure algorithm performance in a simple network and also in a satellite shell network. Both algorithms discussed have advantages and disadvantages, but the Merlin and Segall algorithm is shown to provide exclusive freedom from packet looping. >

A class of adaptive routing and link assignment algorithms for large-scale networks with dynamic topology

Abstract: The authors present novel algorithms for adaptive routing and link assignment, which can be used in a large-scale network (1000-10000 nodes) with dynamic topology and stress. Special attention was given to performance (delay, throughput, and survivability) and implementation cost issues as the size of the network grows. These costs are controlled by a logical partitioning of the network into areas. The proposed class of algorithms addresses the following key issues: maintenance of up-to-date routing information in the presence of dynamics, robustness to failures that can partition areas, optimization of routing algorithm performance through multiple path routing, and optimization of network topology for performance metrics of delay, link performance, and connectivity. >

Congestion based routing in packet radio networks

Abstract: The authors develop a routing procedure that is sensitive to the performance of each link in the presence of multiuser interference. They consider a multihop network using code division multiple access (CDMA) and assume an inverse fourth power law for radio signal propagation. They measure link congestion by the mean number of schedulings per successful packet transmitted on the link. The routing algorithm selects the best links from any specified candidate set, and routes end-to-end traffic over the least congested paths. It is possible to have all links in the network as potential candidates. Even if a set of routing links is specified with a uniform routing range, the algorithm performs better than a minimum-hop routing. >