Showing papers on "Destination-Sequenced Distance Vector routing published in 1995"

A distributed routing algorithm for mobile wireless networks

Abstract: We present a loop-free, distributed routing protocol for mobile packet radio networks. The protocol is 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 nearly-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's uniqueness stems from its ability to maintain source-initiated, loop-free multipath routing only to desired destinations with minimal overhead in a randomly varying topology. 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 which is well-suited to the high-rate topological change environment envisioned here. For each protocol, emphasis is placed on examining how these performance measures vary as a function of the rate of topological changes, network topology, and message traffic level. The results indicate the new protocol generally outperforms the alternative protocol at all rates of change for heavy traffic conditions, whereas the opposite is true for light traffic. Both protocols significantly outperform flooding for all rates of change except at ultra-high rates where all algorithms collapse. The network topology, whether dense or sparsely connected, is not seen to be a major factor in the relative performance of the algorithms.

A necessary and sufficient condition for deadlock-free adaptive routing in wormhole networks

Abstract: Deadlock avoidance is a key issue in wormhole networks. A first approach by W.J. Dally and C.L. Seitz (1987) consists of removing the cyclic dependencies between channels. Many deterministic and adaptive routing algorithms have been proposed based on that approach. Although the absence of cyclic dependencies is a necessary and sufficient condition for deadlock-free deterministic routing, it is only a sufficient condition for deadlock-free adaptive routing. A more powerful approach by J. Duato (1991) only requires the absence of cyclic dependencies on a connected channel subset. The remaining channels can be used in almost any way. In this paper, we show that the previously mentioned approach is also a sufficient condition. Moreover, we propose a necessary and sufficient condition for deadlock-free adaptive routing. This condition is the key for the design of fully adaptive routing algorithms with minimum restrictions, An example shows the application of the new theory. >

A Location Based Heuristic for General Routing Problems

Abstract: We present a general framework for modeling routing problems based on formulating them as a traditional location problem called the capacitated concentrator location problem. We apply this framework to two classical routing problems: the capacitated vehicle routing problem and the inventory routing problem. In the former case, the heuristic is proven to be asymptotically optimal for any distribution of customer demands and locations. Computational experiments show that the heuristic performs well for both problems and, in most cases, outperforms all published heuristics on a set of standard test problems.

Routing subject to quality of service constraints in integrated communication networks

Abstract: With increasingly diverse QOS requirements, it is impractical to continue to rely on conventional routing paradigms that emphasize the search for an optimal path based on a predetermined metric, or a particular function of multiple metrics. Modern routing strategies must not only be adaptive to network changes but also offer considerable economy of scope. We consider the problem of routing in networks subject to QOS constraints. After providing an overview of prior routing work, we define various QOS constraints. We present a call architecture that may be used for QOS matching and a connection management mechanism for network resource allocation. We discuss fallback routing, and review some existing routing frameworks. We also present a new rule-based, call-by-call source routing strategy for integrated communication networks. >

Routing in Communications Networks

Abstract: I. CIRCUIT-SWITCHING NETWORKS. AT&Ts Dynamic Routing Network, G.R. Ash Dynamic Alternative Routing, R.J. Gibbens, F.P. Kelly, and P.B. Key II. PACKET-SWITCHING NETWORKS. Distance Vector Routing, G.S. Malkin and M.E. Steenstrup Inter-Domain Routing: EGP, BGP, and IDRP, Y. Rekhter Link State Routing, J. Moy AppleTalk Routing, A.B. Oppenheimer and F. Kuang SNA Routing, A. Garuge III. HIGH-SPEED NETWORKS. Routing in Optical Networks, J. Bannister, M. Gerla, and M. Kovacevic On Routing in ATM Networks, S. Gupta, K.W. Ross, and M. El Zarki Routing in the plaNET Network, I. Cidon and R. Guerin Deflection Routing, F. Borgonovo IV. MOBILE NETWORKS. Routing in Cellular Mobile Radio Communications Networks, J. Ketchum Packet Radio Routing, G.S. Lauder

Competitive routing of virtual circuits in ATM networks

Abstract: Classical routing and admission control strategies achieve provably good performance by relying on an assumption that the virtual circuits arrival pattern can be described by some a priori known probabilistic model. A new on-line routing framework, based on the notion of competitive analysis, was proposed. This framework is geared toward design of strategies that have provably good performance even in the case where there are no statistical assumptions on the arrival pattern and parameters of the virtual circuits. The on-line strategies motivated by this framework are quite different from the min-hop and reservation-based strategies. This paper surveys the on-line routing framework, the proposed routing and admission control strategies, and discusses some of the implementation issues. >

A family of fault-tolerant routing protocols for direct multiprocessor networks

Abstract: Our goal is to reconcile the conflicting demands of performance and fault-tolerance in interprocessor communication. To this end, we propose a pipelined communication mechanism-pipelined circuit-switching (PCS)-which is a variant of the well known wormhole routing (WR) mechanism. PCS relaxes some of the routing constraints imposed by WR and as a result enables routing behavior that cannot otherwise be realized. This paper presents a new class of adaptive routing algorithms-misrouting backtracking with m misroutes (MB-m). This class of routing algorithms is made possible by PCS. We provide an analysis of the performance and static fault-tolerant properties of MB-m. The results of an experimental evaluation of PCS and MB-3 are also presented. This methodology provides performance approaching that of WR, while realizing a level of resilience to static faults that is difficult to achieve with WR. >

An improved heuristic for the period vehicle routing problem

Abstract: In the period vehicle routing problem, each customer requires a certain number of deliveries per week. Given these frequency requirements, customers must be allocated to days. A vehicle routing problem is solved over each day. We have improved upon best-known solutions to problems from the literature using a new heuristic procedure. The heuristic also works well on 19 newly generated test problems.

Bandwidth-delay based routing algorithms

Abstract: Multimedia applications often require guaranteed quality of service and resource reservation, which has raised a number of challenging technical issues for routing. We consider two new routing algorithms based on bandwidth and delay metrics. The implications of routing metrics on path computation are examined and the rationales behind the selection of bandwidth and delay metrics are discussed. Two new routing algorithms based on bandwidth and delay metrics are presented and some of their important properties are investigated.

Evaluation of multicast routing algorithms for real-time communication on high-speed networks

Abstract: Multicast (MC) routing algorithms capable of satisfying the QoS requirements of real-time applications will be essential for future high-speed networks. We compare the performance of all of the important MC routing algorithms when applied to networks with asymmetric link loads. Each algorithm is judged based on the quality of the MC tree it generates and its efficiency in managing the network resources. Simulation results over random networks show that unconstrained algorithms are not capable of fulfilling the QoS requirements of real-time applications in wide-area networks. One algorithm, reverse path multicasting, is not suitable for asymmetric networks irrespective of the requirements of the application. The three constrained Steiner tree (CST) heuristics reported to date are also studied. Simulations show that all three heuristics behave similarly and that they can manage the network efficiently and construct low cost MC trees that satisfy the QoS requirements of real-time traffic. The execution times of the CST heuristics depend on the MC group size, but they are always larger than those of the unconstrained algorithms.

ROMM routing on mesh and torus networks

Abstract: ROMM is a class of Randomized, Oblivious, Multi--phase, Minimal routing algorithms. ROMM routing offers a potential for improved performance compared to both fully randomized algorithms and deterministic oblivious algorithms, under both light and heavy loads. ROMM routing also offers close to best case performance for many common routing problems. In previous work, these claims were supported by extensive simulations on binary cube networks [30, 31]. Here we present analytical and empirical results for ROMM routing on wormhole routed mesh and torus networks. Our simulations show that ROMM algorithms can perform several representative routing tasks 1.5 to 3 times faster than fully randomized algorithms, for medium--sized networks. Furthermore, ROMM algorithms are always competitive with deterministic, oblivious routing, and in some cases, up to 2 times faster.

Core selection methods for multicast routing

Abstract: Multicast routing is an important topic of both theoretical and practical interest. Several proposed multicast routing algorithms involve the designation of one or more network nodes as the "center" of the routing tree for each multicast group. The choice of this designated router (which we refer to as the "core") influences the shape of the multicast routing tree, and thus influences the performance of the routing scheme. We investigate the relationship between the choice of core and three performance measures. Specifically, we compare various methods of selecting a core with respect to their effect on the bandwidth, delay, and traffic concentration. We conclude that simple methods are adequate for widely distributed groups, but that the addition of group information can be leveraged to improve performance especially when the group is small or exhibits a high degree of locality. We also conclude that core choice can be used to control traffic concentration, in fact traffic concentration effects can be ameliorated by appropriate core choice policies.

A new exact algorithm for the vehicle routing problem based on q -paths and k -shortest paths relaxations

Abstract: We consider the basic Vehicle Routing Problem (VRP) in which a fleet ofM identical vehicles stationed at a central depot is to be optimally routed to supply customers with known demands subject only to vehicle capacity constraints. In this paper, we present an exact algorithm for solving the VRP that uses lower bounds obtained from a combination of two relaxations of the original problem which are based on the computation ofq-paths andk-shortest paths. A set of reduction tests derived from the computation of these bounds is applied to reduce the size of the problem and to improve the quality of the bounds. The resulting lower bounds are then embedded into a tree-search procedure to solve the problem optimally. Computational results are presented for a number of problems taken from the literature. The results demonstrate the effectiveness of the proposed method in solving problems involving up to about 50 customers and in providing tight lower bounds for problems up to about 150 customers.

Distributed, scalable routing based on vectors of link states

Abstract: We have present a new method for distributed routing in computer networks and internets using link-state information. Link vector algorithms (LVA) are introduced for the distributed maintenance of routing information in large networks and internets.

Chapter 5 Arc routing methods and applications

Abstract: Publisher Summary The term "arc routing" refers to routing problems where the key service activity is to cover arcs of a transportation network. In contrast to node routing, where the key service activity occurs at the nodes (customer sites) and arcs are of interest only as elements of paths that connect the nodes, arc routing focuses on the traversal of edges. Practical examples include the routing of street sweepers, snow-plowing, salt gritting (covering streets with salt grit), and inspection of streets for maintenance, postal delivery, and meter reading. In all examples, each street segment must be covered in its entirety. In meter reading, postal delivery, and the delivery of telephone books, the density of the customer locations along a street segment is sufficiently high to consider the street segment as a whole as the service entity. The basic methodology of arc routing by discussing generic arc routing models and their solution techniques is discussed. The chapter covers well-known postman problems that can be regarded as the classical problems of arc routing. The basic objective of these problems is to cover all arcs of a given network with an Euler cycle of minimum cost. The chapter considers the capacitated arc routing problem, where each vehicle tour (cycle) must observe an explicit capacity constraint. Two manufacturing problems that can be modeled as rural postman problems and also mentions other routing applications are discussed in the chapter.

The message flow model for routing in wormhole-routed networks

Abstract: In this paper, we introduce a new approach to deadlock-free routing in wormhole-routed networks called the message flow model. This method may be used to develop deterministic, partially-adaptive, and fully-adaptive routing algorithms for wormhole-routed networks with arbitrary topologies. We first establish the necessary and sufficient condition for deadlock free routing, based on the analysis of the message flow on each channel. We then use the model to develop new adaptive routing algorithms for 2D meshes. >

Topological design and routing for low-Earth orbit satellite networks

Abstract: We investigate a topological design and routing problem for low Earth orbit (LEO) satellite communication networks where each satellite can have a limited number of direct inter-satellite links (ISLs) to a subset of satellites within its line-of-sight. First, we model LEO satellite network as a FSA (finite state automaton) using satellite constellation information. Second, we solve a combined topological design and routing problem for each configuration corresponding to a state in the FSA. The topological design (or link assignment) problem deals with the selection of ISLs, and the routing problem handles the traffic distribution over the selected links to maximize the number of carried calls. This NP-complete mixed integer optimization problem is solved by a two-step heuristic algorithm that first solves the topological design problem, and then finds the optimal routing. The algorithm is iterated using the simulated annealing technique until the near-optimal solution is found. The link assignment table and the routing table that are pre-calculated off-line for each state are loaded into the satellites and a new set of these tables are retrieved at each state transition. The simulation result shows that the proposed method is applicable to practical LEO satellite networks.

Communication in Multicomputers with Nonconvex Faults

Abstract: A technique to enhance multicomputer routers for fault-tolerant routing with modest increase in routing complexity and resource requirements is described. This method handles solid faults in meshes, which includes all convex faults and many practical nonconvex faults, for example, faults in the shape of L or T. As examples of the proposed method, adaptive and nonadaptive fault-tolerant routing algorithms using four virtual channels per physical channel are described.

Fault-tolerant adaptive routing for two-dimensional meshes

Abstract: Many massively parallel computers in use today utilize simple deterministic XY wormhole routing to transmit messages between nodes. Because XY routing does not provide any routing adaptability, it lacks the ability to avoid congested links, as well as faults. Therefore, the focus of this paper will be two-fold: improving the performance of wormhole routing and providing fault tolerance for up to N-1 faults in an N/spl times/N two-dimensional mesh. A simulation model based on the Intel Paragon is presented that compares several known routing strategies with the proposed strategy to illustrate how local state information can be used to provide a potential network throughput improvement of up to 20%, while achieving fault tolerance. >

Hierarchical distance-vector multicast routing for the MBone

Abstract: The exponential growth of the Multicast Back-bone (MBone) has resulted in increased routing overhead and processing costs. In this paper we propose a two-level hierarchical routing model as a solution to this problem. This approach involves partitioning the MBone into non-overlapping regions using DVMRP as the inter-region routing protocol; intra-region routing may be accomplished by any of a number of existing multicast protocols. Our design is flexible enough to accommodate additional levels of hierarchy, and protocols other than DVMRP at the higher levels. The unique feature of this approach is the independence of the higher level routing protocol from the subnet addresses, which allows for easy incremental deployment with small changes to existing intra-region protocols.

A two-phase algorithm for the partial accessibility constrained vehicle routing problem

Abstract: In the partial accessibility constrained vehicle routing problem, a route can be covered by two types of vehicles, i.e. truck or truck + trailer. Some customers are accessible by both vehicle types, whereas others solely by trucks. After introducing an integer programming formulation for the problem, we describe a two-phase heuristic method which extends a classical vehicle routing algorithm. Since it is necessary to solve a combinatorial problem that has some similarities with the generalized assignment problem, we propose an enumerative procedure in which bounds are obtained from a Lagrangian relaxation. The routine provides very encouraging results on a set of test problems.

Vehicle Routing Problem with Fuzzy Due-Time Using Genetic Algorithms

Abstract: 1050 preference very well. Even though customers are asked to provide a fixed time window for service, they really hope to be served at a desired time if possible, We call such a desired time the due-time, In such case, the preference information of customers can be naturally represented as a convex fuzzy number with respect to the satisfaction for service time, In the paper, we suggest to use the concept of fuzzy due-time to replace the concept of time window because it can describe customers preference better than fixed time-window. Thus we can use the mathematics of fuzzy calculus to handle these imprecise descriptions of cus-

Adaptive and dynamic message routing system for multinode wormhole networks

Abstract: In a multinode communication or multiprocessor network, messages are communicated from one node to another using an adaptive and dynamic routing scheme. The routing scheme includes two-level multi-path routing tables at each node to ensure efficient delivery of the messages. An entry in the level-1 table identifies a group of nodes and entry in the level-2 table identifies the address for each node within that group. The routing scheme also includes a deflection counter in each message header to avoid endless rerouting of messages and an exponential backoff and retry policy to avoid deadlocks.

Method and apparatus for storing and retrieving routing information in a network node

Abstract: Method and apparatus for storing and retrieving routing information in a node of a network, such as an ATM network, are disclosed. A routing table in each node of the network stores the routing information for each active call connection through the node, for example, identified by a virtual path identifier (VPI) and a virtual channel identifier (VCI). The routing table is indexed by a modified header error control (HEC) value, which may be the actual HEC value associated with a given cell, or a value calculated therefrom. Upon receipt of an incoming cell at a network node, the modified HEC value is calculated, to access the appropriate entry of the routing table. The routing table preferably stores a pointer to a memory location, such as a linked list of data structures, storing the actual routing information for each connection. An intermediate node data structure preferably stores the routing information for a particular connection through an intermediate node of the ATM network, while a leaf node data structure preferably stores the routing information for a particular connection associated with a leaf node of the ATM network. If a data structure in the indicated linked list has a VPI/VCI value matching the VPI/VCI value in the received cell header, the routing information for the next link of the call connection is retrieved, and the cell header information is validated.

Minimum-cost bounded-skew clock routing

Abstract: In this paper, we present a new clock routing algorithm which minimizes total wirelength under any given path-length skew bound. The algorithm constructs a bounded-skew tree (BST) in two steps: (i) a bottom-up phase to construct a binary tree of shortest-distance feasible regions which represent the loci of possible placements of clock entry points, and (ii) a top-down phase to determine the exact locations of clock entry points. Experimental results show that our clock routing algorithm, named BST/DME, can produce a set of routing solutions with skew and wirelength trade-off.

Link-state routing

Abstract: ƒ Same assumptions/goals, but different idea than DV: ƒ Tell all routers the topology and have each compute best paths ƒ Two phases: 1. Topology dissemination (flooding)-New News travels fast.-Old News should eventually be forgotten 2. Shortest-path calculation (Dijkstra's algorithm)-nlogn

Distance-vector routing

Abstract: Your program must start up and read a configuration file, the configuration file will provide you with the IP addresses of your directly connected neighbors, and the cost to reach those neighbors. Your program must connect to the IP addresses specified in the configuration file. Note that to bootstrap the network you are going to need to have your program retry connections that fail. Your program must also accept incoming IP connections, from neighbors, or from my master control client, which may inform you of a link cost change, or may ask you to deliver a message to a particular IP address. You can write your program in the language of your choice, however the program must run on Linux in the Olin 202 lab.

A theory of deadlock-free adaptive multicast routing in wormhole networks

Abstract: A theory for the design of deadlock-free adaptive routing algorithms for wormhole networks, proposed by the author (1991, 1993), supplies sufficient conditions for an adaptive routing algorithm to be deadlock-free, even when there are cyclic dependencies between channels. Also, two design methodologies were proposed. Multicast communication refers to the delivery of the same message from one source node to an arbitrary number of destination nodes. A tree-like routing scheme is not suitable for hardware-supported multicast in wormhole networks because it produces many headers for each message, drastically increasing the probability of a message being blocked. A path-based multicast routing model was proposed by Lin and Ni (1991) for multicomputers with 2D-mesh and hypercube topologies. In this model, messages are not replicated at intermediate nodes. This paper develops the theoretical background for the design of deadlock-free adaptive multicast routing algorithms. This theory is valid for wormhole networks using the path-based routing model. It is also valid when messages with a single destination and multiple destinations are mixed together. The new channel dependencies produced by messages with several destinations are studied. Also, two theorems are proposed, developing conditions to verify that an adaptive multicast routing algorithm is deadlock-free, even when there are cyclic dependencies between channels. As an example, the multicast routing algorithms of Lin and Ni are extended, so that they can take advantage of the alternative paths offered by the network. >

System for customer configuration of call routing in a telecommunications network

Abstract: In a telecommunications network operable for routing calls such as 800 calls, to a plurality of customer destinations, a system allows the customer to configure the routing of calls by entering selected call routing criteria such as a call-routing map associated with a time frame for implementation thereof included as part of an overall routing plan. The routing map includes the desired allocation of calls placed from a customer defined origination region to selected ones of the customer's call receiving destinations. Using the customer supplied criteria, the system then composes a set of call-handling statements, also called time features, which the network then compiles into an executable routing scheme for translating the dialed number into the physical number associated with the selected customer destination.