Showing papers on "Zone Routing Protocol published in 1994"

Highly dynamic Destination-Sequenced Distance-Vector routing (DSDV) for mobile computers

Abstract: An ad-hoc network is the cooperative engagement of a collection of Mobile Hosts without the required intervention of any centralized Access Point. In this paper we present an innovative design for the operation of such ad-hoc networks. The basic idea of the design is to operate each Mobile Host as a specialized router, which periodically advertises its view of the interconnection topology with other Mobile Hosts within the network. This amounts to a new sort of routing protocol. We have investigated modifications to the basic Bellman-Ford routing mechanisms, as specified by RIP [5], to make it suitable for a dynamic and self-starting network mechanism as is required by users wishing to utilize ad hoc networks. Our modifications address some of the previous objections to the use of Bellman-Ford, related to the poor looping properties of such algorithms in the face of broken links and the resulting time dependent nature of the interconnection topology describing the links between the Mobile Hosts. Finally, we describe the ways in which the basic network-layer routing can be modified to provide MAC-layer support for ad-hoc networks.

An architecture for wide-area multicast routing

Abstract: Existing multicast routing mechanisms were intended for use within regions where a group is widely represented or bandwidth is universally plentiful. When group members, and senders to those group members, are distributed sparsely across a wide area, these schemes are not efficient; data packets or membership report information are occasionally sent over many links that do not lead to receivers or senders, respectively. We have developed a multicast routing architecture that efficiently establishes distribution trees across wide area internets, where many groups will be sparsely represented. Efficiency is measured in terms of the state, control message processing, and data packet processing, required across the entire network in order to deliver data packets to the members of the group.Our Protocol Independent Multicast (PIM) architecture: (a) maintains the traditional IP multicast service model of receiver-initiated membership; (b) can be configured to adapt to different multicast group and network characteristics; (c) is not dependent on a specific unicast routing protocol; and (d) uses soft-state mechanisms to adapt to underlying network conditions and group dynamics. The robustness, flexibility, and scaling properties of this architecture make it well suited to large heterogeneous inter-networks.

Reliable transport protocol for internetwork routing

Abstract: A reliable transport protocol, suitable for routing protocols, that works with unicast transmission and multicast transmission, and an improved routing protocol based thereon. Multicast transmissions can be interspersed with unicast transmissions in situations where some of the receivers have received all of the packets sent to them and others have not. A mechanism to deliver multicast packets quickly to some receivers, even when there are unacknowledged packets pending for other receivers. When a packet is multicast from a sender node to all of its neighbors, the sender puts the packet on a queue for each neighbor and retransmits the packet if an acknowledgement has not been received within a predetermined period of time. If the packet is retransmitted, it is transmitted as a unicast. The invention takes advantage of the fact that the sender already has to maintain state information to determine who has not received its packets. A technique for distributing routing information gathered by a router outside an autonomous system of routers using the same routing protocol. A metric calculated by an identical routing protocol or a different routing protocol may be distributed and used by routers in a different autonomous system. Packets may be labeled with authentication information or with an administrative tag that specifies a method of routing in response to policy considerations.

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 [8] consists of removing the cyclic dependencies between channels. Although this 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 [12] 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 propose a necessary and sufficient condition for deadlock-free adaptive routing. This condition is the key for the design of maximally adaptive routing algorithms with minimum restrictions. Some examples are given, showing the application of the new theory. In particular, we propose a partially adaptive routing algorithm for k-ary n-cubes which doubles the throughput without increasing the hardware complexity significantly.

EIGRP--A Fast Routing Protocol based on Distance Vectors

Abstract: EIGRP{A FAST ROUTING PROTOCOL BASED ON DISTANCE VECTORS Bob Albrightson Cisco Systems Menlo Park, CA 94025 albright@cisco.com J.J. Garcia-Luna-Aceves University of California Santa Cruz, CA 95064 jj@cse.ucsc.edu Joanne Boyle Cisco Systems Menlo Park, CA 94025 boyle@cisco.com Abstract Early routing protocols were based on distance vectors; they were very simple and easy to implement but had the severe drawbacks of counting to innity and routing loops. These problems were reduced using such techniques as split horizon and hold-downs; however, for these techniques to work in practice, long convergence times are introduced. Routing protocols based on link states have been implemented to address the problem of slow convergence in distance-vector protocols, but they add complexity in conguration and troubleshooting. We present a new distance-vector protocol that converges as quickly as current link-state protocols, while maintaining loop freedom at every instant. The protocol is based on three main elements: a transport algorithm that supports the reliable exchange of messages among routers, the diusing update algorithm, which computes shortest paths distributedly, and modules that permit the operation of the new routing protocol in a multiprotocol environment. 1 INTRODUCTION Today's intradomain routing protocols can be classied as distance-vector or link-state protocols. In a distance-vector protocol, a router knows the length of the shortest path from each neighbor node to every network destination, and uses this information to compute the shortest path and next router in the path to each destination. A router sends update messages to its neighbors, who in turn process the messages and send messages of their own, if needed. Each update message contains a vector of one or more entries, each of which species, as a minimum, the distance to a given destination. In contrast, in a link-state protocol a router must receive information about the entire topology to compute the shortest path to each destination using a local shortest-path algorithm such as Dijkstra's algorithm [1]. Each router broadcasts update messages, containing the state of each of the router's adjacent links, to every other router in the network. The distance vector protocols used in the Internet thus far are based on variants of the distributed Bellman-Ford algorithm (DBF) for shortest-path computation [1]. The primary disadvantage of DBF is that incorrect entries in routing tables may form routing-table loops for one or more destinations whenever link costs increase [9]. Because a router chooses as its successor to a destination any neighbor router who appears to oer the shortest path to that destination, the router may choose paths that lead to loops for as long as those neighbor routers with viable paths to the destination oer path lengths longer than those paths leading to loops. The worst case of this problem is rather severe: when routers fail or the network partitions, a router can detect such events only after it has considered all possible path lengths to the one or more destinations that have become unreachable through any of its neighbors. Accordingly, this

Adaptive deadlock- and livelock-free routing with all minimal paths in torus networks

Abstract: This paper consists of two parts. In the first part, two new algorithms for deadlock- and livelock-free wormhole routing in the torus network are presented. The first algorithm, called Channels, is for the n-dimensional torus network. This technique is fully-adaptive minimal, that is, all paths with a minimal number of hops from source to destination are available for routing, and needs only five virtual channels per bidirectional link, the lowest channel requirement known in the literature for fully-adaptive minimal worm-hole routing. In addition, this result also yields the lowest buffer requirement known in the literature for packet-switched fully-adaptive minimal routing. The second algorithm, called 4-Classes, is for the bidimensional torus network. This technique is fully-adaptive minimal and requires only eight virtual channels per bidirectional link. Also, it allows for a highly parallel implementation of its associated routing node. In the second part of this paper, four worm-hole routing techniques for the two-dimensional torus are experimentally evaluated using a dynamic message injection model and different traffic patterns and message lengths. >

Compressionless routing: a framework for adaptive and fault-tolerant routing

Abstract: Compressionless Routing (GR) is a new adaptive routing framework which provides a unified framework for efficient deadlock-free adaptive routing and fault-tolerance. CR exploits the tight-coupling between wormhole routers for flow control to detect potential deadlock situations and recover from them. Fault-tolerant Compressionless Routing (FCR) extends Compressionless Routing to support end-to-end fault-tolerant delivery. Detailed routing algorithms, implementation complexity and performance simulation results for CR and FCR are presented.CR has the following advantages: deadlock-free adaptive routing in torus networks with no virtual channels, simple router designs, order-preserving message transmission, applicability to a wide variety of network topologies, and elimination of the need for buffer allocation messages. FCR has the following advantages: tolerates transient faults while maintaining data integrity (nonstop fault-tolerance), tolerates permanent faults, can be applied to a wide variety of network topologies, and eliminates the need for software buffering and retry for reliability. These advantages of CR and FCR not only simplify hardware support for adaptive routing and fault-tolerance, they also can simplify communication software layers.

Static routing system

Abstract: A desired static route is read from a static routing table and a polling is effected on a network connected to a terminal at regular intervals. If a normal response is issued from the network, then information about the above static route is entered in a routing table. If no normal response is delivered from the network, then the information about the static routes entered in the routing table is deleted.

Routing method for a hierarchical communications network, and a hierarchical communications network having improved routing

Abstract: A method and apparatus for selecting routes in a hierarchical communications network wherein a number of mutually isolated areas are provided at a first level, which areas are mutually linked at a second level. In the network, routing devices are provided at both levels. For selecting a route from a first area to a second area, use is made of routing information stored in the routing devices of the first level, relating to the first level and to reaching the nearest routing device of the second level. Use is also made, in the routing devices of the first level, of routing information relating to the second level.

Efficient fully adaptive wormhole routing in n-dimensional meshes

Abstract: An efficient fully adaptive wormhole routing algorithm for n-dimensional meshes is developed. The routing algorithm provides full adaptivity at a cost of one additional virtual channel per physical channel irrespective of the number of dimensions of the network. The algorithm is based on dividing the network graph into two acyclic graphs that contain all of the physical channels in the system. Virtual channels are classified as either waiting or nonwaiting channels. Busy channels that a message waits for to become available are classified as waiting channels, otherwise they are classified as nonwaiting channels. Thus, a message considers nonwaiting channels first to reach its destination. If all non-waiting channels are busy, the message considers waiting channels. Messages acquire waiting channels in two phases. In each phase, waiting channels belonging to one acyclic network graph are traversed. This 2-phase routing algorithm could be either minimal or nonminimal. However, we concentrate on minimal routing. It is demonstrated that this adaptive routing algorithm can utilize the virtual paths (channels) between any two nodes more efficiently than any of the present algorithms with the same hardware requirement. >

Multicast routing in self-routing multistage networks

Abstract: The authors present a study on multicast routing algorithms for the self-routing multistage networks. This work is based on the use of the cube concept which consists of a group of outlets reachable in one pass through the network. A multicast connection is decomposed into associated cubes such that each cube can be self-routed through the network. The context of this work is a recursive scheme for multistage network where the outlets are fed back to the inlets through external links. Three routing algorithms are proposed. The emphasis is on evaluating the performance of those algorithms in terms of two metrics. Extensive results from analysis and simulations are given to derive insights into the performance of the proposed routing algorithms. >

MDP routing in ATM networks using virtual path concept

Abstract: The virtual path (VP) concept has been proposed to simplify traffic control and resource management in future B-ISDN. In particular, call setup processing can be significantly reduced when resources are reserved on VPs. However, this advantage is offset by a decrease in statistical multiplexing gains of the networks. The focus of this paper is on how to improve bandwidth efficiency through adaptive routing when capacity is reserved on all VPs. The authors first examine two VP capacity reservation strategies. They then design and evaluate computationally feasible Markov decision process-based routing algorithms and show that the network blocking probability can be significantly reduced by MDP routing. >

Optimum routing of multicast streams

Abstract: The authors show that the problem of optimally routing multicast streams can be formulated as an integer programming problem. They propose an efficient solution technique, composed of two parts: (i) an extension to the decomposition principle, to speed up the linear relaxation of the problem, and (ii) enhanced value-fixing rules, to prune the search space for the integer problem. They characterize the reduction in run time gained using these techniques. Finally, they compare the run times for the optimum multicast routing algorithm and for existing heuristic algorithms. >

Controlling alternate routing in general-mesh packet flow networks

Abstract: High-speed packet networks will begin to support services that need Quality-of-Service (QoS) guarantees. Guaranteeing QoS typically translates to reserving resources for the duration of a call. We propose a state-dependent routing scheme that builds on any base state-independent routing scheme, by routing flows which are blocked on their primary paths (as selected by the state-independent scheme) onto alternate paths in a manner that is guaranteed—under certain Poisson assumptions— to improve on the performance of the base state-independent scheme. Our scheme only requires each node to have state information of those links that are incident on it. Such a scheme is of value when either the base state-independent scheme is already in place and a complete overhaul of the routing algorithm is undesirable, or when the state (reserved flows) of a link changes fast enough that the timely update of state information is infeasible to all possible call-originators. The performance improvements due to our controlled alternate routing scheme are borne out from simulations conducted on a fully-connected 4-node network, as well as on a sparsely-connected 12-node network modeled on the NSFNet T3 Backbone.

Fully adaptive minimal deadlock-free packet routing in hypercubes, meshes, and other networks: algorithms and simulations

Abstract: This paper deals with the problem of packet-switched routing in parallel machines. Several new routing algorithms for different interconnection networks are presented. While the new techniques apply to a wide variety of networks, routing algorithms will be shown for the hypercube, the two-dimensional mesh, and the shuffle-exchange. Although the new techniques are designed for packet routing, they can be used alternatively for virtual cut-through routing models. The techniques presented for hypercubes and meshes are fully-adaptive and minimal. A fully-adaptive and minimal routing is one in which all possible minimal paths between a source and a destination are of potential use at the time a message is injected into the network. Minimal paths followed by messages ultimately depend on the local congestion encountered in each node of the network. All of the new techniques are completely free of deadlock situations. >

A multiple-path routing strategy for vehicle route guidance systems

Abstract: This paper analyzes the transportation effectiveness of a multiple-path routing strategy using traffic simulation from the perspective of planning and designing a vehicle route guidance system. The test results indicate that the multiple-path routing strategy performs better than the commonly used shortest-path routing strategy.

Some routing problems on broadband ISDN

Abstract: In this paper, three related virtual channel routing problems on Broadband ISDN are investigated and shown to be NP-complete A distributed routing heuristic is proposed to reduce the call blocking rate while preserving a fast call setup time Various traffic patterns and network topologies are employed to evaluate the performance of the proposed heuristic by simulations Two existing famous routing schemes are also applied for comparison The simulation results show that the proposed heuristic performs better in most cases than the other two schemes

Flexible routing and addressing for a next generation IP

Abstract: Due to a limited address space and poor scaling of backbone routing information, the Internet Protocol (IP) is rapidly reaching the end of its useful lifetime. The Simple Internet Protocol Plus (SIPP), a proposed next generation Internet Protocol, solves these problems with larger internet layer addresses. In addition, SIPP provides a number of advanced routing and addressing capabilities including mobility, extended (variable-length) addressing, provider selection, and certain forms of multicast. These capabilities are all achieved through a single mechanism, a generalization of the IP loose source route. We argue that, for reasons of simplicity and evolvability, a single powerful mechanism to achieve a wide range of routing and addressing functions is preferable to having multiple specific mechanisms, one for each function.

The MaTPi protocol: masking tuning times through pipelining in WDM optical networks

Abstract: The authors propose MaTPi, a new media-access protocol for the efficient utilization of resources in a local-area optical WDMA network. Most of the earlier work on reservation based media access protocols for single-hop optical networks has assumed the availability of state-of-the-art transmitters and/or receivers which are capable of tuning to the required wavelengths within nanoseconds. Their protocol operates in the region where the tuning times of the end-devices are of the same order of magnitude as the transmission time of a packet. In the basic MaTPi protocol, network throughput is improved by effectively overlapping the tuning duration of a transmitter in a node with the transmitting times of lasers in other nodes. They extend this basic protocol to the mult-MaTPi protocol, where each node has more than one transmitter to further improve the bandwidth efficiency of the network. Preliminary simulation results indicate that this practical protocol is indeed capable of achieving high throughput with low-cost, off-the-shelf components. A number of extensions to this protocol are also discussed. >

An efficient store-and-forward protocol for a shallow-water acoustic local area network

Abstract: A store-and-forward protocol for a shallow-water acoustic local area network is presented. This protocol permits random deployment of an unlimited number of possibly mobile acoustic modems in littoral zones. Modem connectivity is adaptively learned and permits the incorporation of fresh modems into an operating network. The main points of the protocol initialization, maintenance, routing, and rerouting algorithms are presented. The protocol borrows from existing algorithms for packet radio networks and presents methods to decrease delay and retransmission of packets to conserve the limited modem power. >

Scouting: fully adaptive, deadlock-free routing in faulty pipelined networks

Abstract: Adaptive routing protocols based on message pipelining using wormhole routing (WR) can provide superior performance However, the occurrence of faults can lead to situations that may produce deadlock Variants of adaptive WR have been introduced (PT Gaughan and S Yalamanchili, 1992) that employ backtracking and misrouting to first establish a path, followed by message pipelining (pipelined circuit switching, or PCS) This scheme avoids deadlock due to faults, but is overly conservative leading to reduced performance The paper introduces a new family of flow control mechanisms ranging from WR to PCS that offers a compromise by only decoupling the routing probe and the data fits the minimal extent required to provide deadlock-free routing in the presence of faults

A Fault-Tolerant Routing Algorithm in Hypercubes

Abstract: Fault-tolerant communication mechanism for multicomputer systems is an important feature to reliability-critical applications. In this paper, we will present a fault-tolerant routing algorithm that has a better performance than a previous work in the sense that it requires less message overhead and the message header needs to be updated at fewer intermediate nodes. A comparison between the algorithms and a previous work is given.

Area-based, loop-free internet routing

Abstract: The diffusing update algorithms (DUAL) constitute a family of distributed routing algorithms that has been shown to be loop-free at every instant, to converge after an arbitrary sequence of link-cost or topological changes, and to outperform all other loop-free routing algorithms previously proposed from the standpoint of the combined temporal, message, and storage complexities. Two hierarchical routing schemes based on DUAL are presented to make it more applicable to very large internets. A scheme based on McQuillan's (1974, 1980) hierarchical routing scheme and a backbone-oriented scheme, similar to the one used in OSPF, are introduced to reduce the amount of routing information maintained at each router. The performance of these schemes is compared by simulation to the performance of the basic DUAL, an ideal routing algorithm based on topology broadcast, and OSPF. The simulation results suggest that DUAL with areas outperforms OSPF, and provide additional insight on the performance of OSPF, EIGRP, and area-based routing algorithms in general. >

Deterministic 1-k Routing on Meshes

Abstract: In 1-k routing each of the n2 processing units of an n x n mesh connected computer initially holds 1 packet which must be routed such that any processor is the destination of at most k packets. This problem has great practical importance in itself and by its implications for hot-potato worm-hole routing.

Dynamic routing in multi-class non-hierarchical networks

Abstract: With the introduction of B-ISDN networks based on ATM, networks supporting heterogeneous services have become a reality. We address the problem of dynamic routing in multiclass networks. The objectives of "sharing" network resources and providing "isolation" between classes are taken into consideration and two distinct classes of routing policies are proposed. The performance characteristics of the proposed routing policies are presented through extensive simulations, and appropriate comparisons are made. >

Computer-supported routing for intelligent networks and personalized wired communications

Abstract: We present the architecture, capabilities, and applications of CSTA, a European ISDN-OSI interface for routing in intelligent networks. It allows computer-supported routing of all types of telephony calls: voice, video, image, and data. This enhances routing in telephony networks in terms of speed, throughput, reliability, support of call priorities, and customization of routing to users requirements. We conclude by highlighting some areas for future research and standardization. >

Hierarchical adaptive routing: a framework for fully adaptive and deadlock-free wormhole routing

Abstract: Adaptive routing can improve network performance and fault-tolerance by providing multiple routing paths. However, the implementation complexity of adaptive routing can be significant, discouraging its use in commercial massively parallel systems. In this paper we introduce Hierarchical Adaptive Routing (HAR), a new adaptive routing framework which provides a unified framework for simple and high performance fully adaptive deadlock-free wormhole routing. HAR divides the physical network into several levels of virtual networks. There is one connection channel between two adjacent virtual networks that allows blocked packets in the higher level to move to the lower level. Different routing algorithms can be used in each virtual network; and the overall network is deadlock-free provided the rotating algorithm in the lowest level virtual network is deadlock-free. However, the routing algorithm in any other virtual network can be fully adaptive, even non-minimal, to increase performance. HAR has three advantages: fully adaptive deadlock-free routing in any non-wrapped and wrapped k-ary n-cube network with 2 and 3 virtual channels respectively, relatively small crossbars, and applicability to a wide variety of network topologies. Detailed implementation and simulation studies of a HAR for 2D mesh networks are presented. >

A new protocol for route discovery in multiple-ring networks. 1. The basic protocol

Abstract: Source routing requires that the source station knows a route to the destination. The paper presents a new bridge protocol for route discovery in multiple-ring networks, where several token-rings are connected by bridges. The protocol gives to the source station an indication of the availability of a route to the destination. If such a route exists, the source is supplied with a description/spl mdash/a list of ring and bridge identities/spl mdash/of the route that is fastest at the time of protocol execution. The main advantage of the new route discovery protocol over the existing one is its communication efficiency: the number of frames used is the sum of the number of rings and number of bridges in the network, as opposed to the exponential function required in the existing protocol. Another advantage of the new protocol is its option that allows determining routes to multiple destinations, thus supporting efficient multicast source routing. >

Route high speed changeover method and router

Abstract: PURPOSE:To reduce considerably a time switched to a backup route after the occurrence of a fault in the router in a network system having a redundant route between LANs and to switch a route at a high speed by having only to mount an additional function to the router without imposing any modification onto a communication terminal equipment. CONSTITUTION:Routers 1, 3 and routers 2, 4 being respectively in backup relation in a route between LANs 7 and 8 send periodically a monitor packet for mutual monitor with each other at an interval shorter than an interval of routing protocol packets in addition to the routing protocol packet for generating a routing table. Thus, the switching time to the backup route on the occurrence of a fault in a router is considerably reduced more than the case with using only a standard routing protocol such as RIP by means of the mutual monitor using the monitor packet. Furthermore, since this method does not give effect on the standard protocol, the effect is obtained without needing revision of an existing communication terminal equipment at all.