Showing papers on "Hazy Sighted Link State Routing Protocol published in 1989"

An adaptive hierarchical routing protocol

Abstract: An adaptive hierarchical routing protocol based on the extension of the new Arpanet scheme is proposed and its simulated performance is presented. The protocol can adapt to rapidly changing environments and works for arbitrarily large networks. A number of existing schemes as well as the proposed scheme are simulated under many different environments and clustering structures. The proposed protocol is found to be superior to the other protocols tested in many different types of network traffic and topological configurations. The results indicate that intercluster links must be reliable, because (1) the failure of these links can significantly degrade the routing performance, even though the protocol does not degrade as badly as the existing scheme and (2) hierarchical routing protocols usually prefer small clusters, which means that there will be many intercluster links. The tradeoff between two conflicting performance criteria, response speed and communication overhead, is shown. >

Sirpent: a high-performance internetworking approach

Abstract: A clear target for computer communication technology is to support a high-performance global internetwork. Current internetworking approaches use either concatenated virtual circuits, as in X.75, or a “universal” internetwork datagram, as in the DoD Internet IP protocol and the ISO connectionless network protocol (CLNP). Both approaches have significant disadvantages.This paper describes Sirpent™ (Source Internetwork Routing Protocol with Extended Network Transfer)1, a new approach to an internetwork architecture that makes source routing the basis for interconnection, rather than an option as in IP. Its benefits include simple switching with low per-packet processing and delay, support for accounting and congestion control, and scalability to a global internetwork. It also supports flexible, user-controlled routing such as required for security, policy-based routing and realtime applications. We also propose a specific internetwork protocol, called VIPER™2, as a realization of the Sirpent approach.

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. >

Robust design and planning of a worldwide intelligent network

Abstract: The authors describe the structure of the worldwide intelligent network (WIN), describe methods for its design and planning, investigate the adequacy of decentralized control for problem-free worldwide call completion, explore the feasibility of adaptive routing and control concepts, discuss network robustness/reliability objectives, and describe a strategy for achieving these objectives for all cooperating international carriers. Several decentralized adaptive routing policies that are particularly attractive in the WIN environment and network performance improvements that can be achieved with the introduction of flexible routing capabilities are characterized. It is shown by example that network integration coupled with flexible routing and bandwidth allocation for preferential treatment of new services provides an effective approach for robust and economical new service provisioning. >

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. >

Multi-packet-routing on mesh connected arrays

Abstract: In this paper we study the problem of routing packets on an r-dimensional mesh-connected array of processors. The focus of this paper lies on routing with each processor containing exactly k packets, k > 2, initially and finally (so-called k-k-routing). For two-dimensional n x n grids the number of transport steps is at most ~kn + O(kn/f(n)) with a buffersize of O(kf(n)). In the special case of a sequence of k permutation routing problems this step count can be reduced to kn + O(kn/f(n)). For an r-dimensional cube, r > 3, with side length n the same technique yields an algorithm with step count [~] ( 2 r 2)n + O(kn/f(n) 1/(r-1)) and a buffer size of O(kf(n)). Furthermore it is shown that splitting large packets into smaller ones has benefits for permutation routing problems. 1 I n t r o d u c t i o n The performance of parallel computation is heavily influenced by the existence of fast data movement algorithms [AJP86]. In this area especially mesh connected processor arrays have drawn attention because of their simple interconnection and their easy scalability. A nl x . . . x n~ mesh connected array is a set mesh(n1,..., n~)of N = n l . . . n~ identical processors where each processor P = (pl,...,p~),O _< Pi _< ni 1, is directly connected to all its nearPermission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and /o r specific permission. @ t989 A C M 0 8 9 7 9 1 3 2 3 X / 8 9 / 0 0 0 6 / 0 3 3 6 $1.50 est neighbours only. A processor Q = ( q l , . . . , q r ) is called nearest neighbour of P iff the manhattan distance between P and Q is 1 (d(P,Q) = Eir=l IPi -qi[)" The control structure of the grid of processors is assumed to be of the MIMD type (Multiple Instruction Multiple Data). That is, each processor has its own program memory, different processors can perform different instructions at the same clock period, there is a global clock, and each processor can send data only to its nearest neighbours during one clock period. Bidirectional communication can occur with all nearest neighbours in one clock cycle. Furthermore, each processor has only a limited number of registers for data (e.g. the buffer size is constant or log N). D e f i n i t i o n I (k -k p a c k e t r o u t i n g ) A k-k pakket routing problem is the problem of transporting k packets from each processor in the mesh to k destination processors. Each processor in the mesh sends and finally receives k packets. More formally a k-k routing problem is described by a (k+l) tuple (mesh, address],..., addressk ) where each addressi is a map from mesh to mesh and for all processors P in the mesh we have k Ei=~ ]address~-l(P)l = k. All the packets in address~-l(mesh) are said to lie in layer i. In the case of k = 1 address1 is a bijective func tion by definition and the problem is then called a permutation routing problem. This basic problem has been extensively studied in the literature. For n × n meshes some algorithms based on sorting only need 3n+O(low order) steps and a buffer*This research was supported by SIEMENS AG, Mfinchen, and by the Deutsche Forschungsgemeinschaft, Grant No. Ku 658/1-1.

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. >

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 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. >