Showing papers on "Dynamic Source 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 routing protocol for packet radio networks

Abstract: : The authors present a new distance-vector routing protocol for a packet radio network. The new distributed routing protocol, Wireless Routing Protocol (WRP), works on the notion of second-to-last hop node to a destination. WRP reduces the number of cases in which a temporary routing loop can occur and also provides a mechanism for the reliable transmission of update messages. The performance of WRP has been compared quantitatively by simulations with that of distributed Bellman-Ford (DBF), DUAL (a loop-free, distance-vector algorithm), and an ideal link-state algorithm (ILS) that represents the state of the art of Internet routing in a highly dynamic environment. The simulation results indicate that WRP is the most efficient of the algorithms simulated in a wireless environment.

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

Adaptive routing protocols for hypercube interconnection networks

Abstract: A taxonomy for characterizing adaptive routing protocols for hypercube interconnection networks (HINs) is presented. The taxonomy is based on classes of routing decisions common to any HIN. This taxonomy is used to discuss existing and proposed protocols. Rather than an exhaustive enumeration of related research, the protocols selected for discussion are intended to be representative of the classes defined by the taxonomy. These protocols are candidates for use in massively parallel architectures configured with HINs. To provide some insight into their behavior in very large HINs, results of simulation studies of representative protocols are presented. >

Method and system for routing packets in a packet communication network using locally constructed routine tables

Abstract: In a packet communication system, wherein nodes are assigned an absolute coordinate-based address and routing decisions are made at each node (S2, S7) without the use of directory-based routing, routing decisions made for a particular packet with an ultimate destination are stored at each node so that the next packet sent by that node to that same ultimate destination can be forwarded in accordance with the previous routing decision made for that destination. Routing decisions are stored locally at each node in a routing table (S6, S12). In one embodiment, nodes also store routing information about the source node for a packet so that when a return packet is received for the original source, the relay node will not have to make a routing decision.

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. >

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.

Performance analysis of mesh interconnection networks with deterministic routing

Abstract: This paper develops detailed analytical performance models for k-ary n-cube networks with single-hit or infinite buffers, wormhole routing, and the nonadaptive deadlock-free routing scheme proposed by Dally and Seitz (1987). In contrast to previous performance studies of such networks, the system is modeled as a closed queueing network that: includes the effects of blocking and pipelining of messages in the network; allows for arbitrary source-destination probability distributions; and explicitly models the virtual channels used in the deadlock-free routing algorithm. The models are used to examine several performance issues for 2-D networks with shared-memory traffic. These results should prove useful for engineering high-performance systems based on low-dimensional k-ary n-cube networks. >

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.

Routing in multihop packet switching networks: Gb/s challenge

Abstract: The authors survey networking solutions that have been proposed for high-speed packet-switched applications. Using these solutions as examples, they identify the specific problems resulting from very high transmission rates and explain how these problems influence the design of high-speed networks and protocols. They conclude that the solutions based on deflection routing are the most promising ones and suggest a number of directions for their evolution. By a packet-switching protocol we mean the network-specific portion of the third OSI layer (i.e., the network layer) of the protocol stack. One part of a packet-switching protocol (according to our definition) is the routing scheme, i.e., the set of rules that assign incoming packets to output links. In general, we can talk about the following three components of the communication subnetwork which are relevant from our point of view: the routing protocol; the congestion-control mechanisms that can be effectively incorporated into the routing protocol; and the network topology. These components are closely related to each other and together offer a single functionality. We discuss routing protocols and congestion-control mechanisms employed in contemporary packet-switched networks, not necessarily in networks operating at very high transmission rates. Then, following some basic definitions related to the topology component, we investigate the challenges posed by the Gb/s transmission rates. >

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.

A preservation-based multicast (RBM) routing protocol for mobile networks: initial route construction phase

Abstract: We propose a combined multicast routing, resource reservation and admission control protocol, termed Reservation-Based Multicast (RBM), that borrows the “Rendez-vous Point” or “Core” concept from multicast routing algorithms proposed for the Internet, but which is intended for operation in mobile networks and routes hierarchically-encoded data streams based on user-specified fidelity requirements, real-time delivery thresholds and prevailing network bandwidth constraints. The protocol exhibits the fully distributed operation and receiver-initiated orientation of these proposed algorithms; but, unlike them, the protocol is tightly coupled to a class of underlying, distributed, unicast routing protocols thereby facilitating operation in a dynamic topology. This paper focuses on the initial route construction phase, assumed to occur during a static “snapshot” of the dynamic topology, and is therefore applicable to fixed networks as well, e.g. the Internet.

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. >

Method and apparatus for deadlock-free routing around an unusable routing component in an N-dimensional network

Abstract: A method and apparatus for deadlock-free routing around an unusable routing component in a network reroutes paths between source and destination nodes by initially identifying an unusable routing component. A shadow direction within the network is then determined, the shadow direction being from the unusable routing component to an edge of the network. The paths between nodes are then rerouted so that the paths bypass the unusable routing component and limit the use of any routing components in the network between the unusable routing component and the edge in the shadow direction.

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.

System for service control point routing

Abstract: The present invention is a service control point (SCP) for use in a telecommunications network, and in particular, as a component of a telecommunications signaling system. The SCP includes multiple databases which allow routing plans to be stored and implemented. The SCP is operable to accept queries from switches for routing information. The SCP is further operable to reply to these queries with information identifying a connection as opposed to a routing number.

Method for automatically routing circuits of very large scale integration (VLSI)

Abstract: An automated routing tool for routing interconnections between circuit elements, standard cells and/or cell blocks of cell-based designs which incorporates the best features of both currently known gate array routing techniques with currently known cell-based routing techniques. The invention eliminates the disadvantages of permitting the detailed router to adjust the relative positions of the circuit elements, standard cells and/or cell blocks during the detailed routing process. The method employs a topology manager which iteratively compacts the circuit topology while at the same time optimizing the routing of the interconnections among the circuit elements, standard cells and/or cell blocks of the circuit design. The method employs bin-based global routing, which identifies expandable boundaries and which provides input to a compaction routine which expands or contracts the expandable areas in accordance with the result of the global routing process. The detailed routing step is not performed until after the relative positions of the circuit elements, cells and/or cell blocks have been already fixed.

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.