Showing papers on "Zone Routing Protocol published in 1996"

Quality-of-service routing for supporting multimedia applications

Abstract: Several new architectures have been developed for supporting multimedia applications such as digital video and audio. However, quality-of-service (QoS) routing is an important element that is still missing from these architectures. In this paper, we consider a number of issues in QoS routing. We first examine the basic problem of QoS routing, namely, finding a path that satisfies multiple constraints, and its implications on routing metric selection, and then present three path computation algorithms for source routing and for hop-by-hop routing.

An efficient routing protocol for wireless networks

Abstract: We present the Wireless Routing Protocol (WRP). In WRP, routing nodes communicate the distance and second-to-last hop for each destination. WRP reduces the number of cases in which a temporary routing loop can occur, which accounts for its fast convergence properties. A detailed proof of correctness is presented and its performance is compared by simulation with the performance of the distributed Bellman-Ford Algorithm (DBF), DUAL (a loop-free distance-vector algorithm) and an Ideal Link-state Algorithm (ILS), which represent the state of the art of internet routing. The simulation results indicate that WRP is the most efficient of the alternatives analyzed.

A novel distributed routing protocol to support ad-hoc mobile computing

Abstract: This paper presents a new, simple and bandwidth-efficient distributed routing protocol for ad-hoc mobile networks. Unlike the conventional distributed routing algorithms, our protocol does not attempt to consistently maintain routing information in every node. In an ad-hoc mobile network where mobile hosts are acting as routers and where routes are made inconsistent by mobile host movements, we employ a new associativity-based routing scheme where a route is selected based on nodes having associativity states that imply periods of stability. In this manner, the routes selected are likely to be long-lived and hence there is no need to restart frequently, resulting in higher attainable throughput. The association property also allows the integration of ad-hoc routing into a BS-oriented wireless LAN environment, providing fault tolerance in times of base station (BS) failures. The protocol is free from loops, deadlock and packet duplicates and has scalable memory requirements. Simulation results obtained reveal that shorter and better routes can be discovered during route re-constructions.

End-to-end routing behavior in the internet

Abstract: The large-scale behavior of routing in the Internet has gone virtually without any formal study, the exception being Chinoy's analysis of the dynamics of Internet routing information [Ch93]. We report on an analysis of 40,000 end-to-end route measurements conducted using repeated "traceroutes" between 37 Internet sites. We analyze the routing behavior for pathological conditions, routing stability, and routing symmetry. For pathologies, we characterize the prevalence of routing loops, erroneous routing, infrastructure failures, and temporary outages. We find that the likelihood of encountering a major routing pathology more than doubled between the end of 1994 and the end of 1995, rising from 1.5% to 3.4%. For routing stability, we define two separate types of stability, "prevalence" meaning the overall likelihood that a particular route is encountered, and "persistence," the likelihood that a route remains unchanged over a long period of time. We find that Internet paths are heavily dominated by a single prevalent route, but that the time periods over which routes persist show wide variation, ranging from seconds up to days. About 2/3's of the Internet paths had routes persisting for either days or weeks. For routing symmetry, we look at the likelihood that a path through the Internet visits at least one different city in the two directions. At the end of 1995, this was the case half the time, and at least one different autonomous system was visited 30% of the time.

Guidelines for creation, selection, and registration of an Autonomous System (AS)

Abstract: This memo discusses when it is appropriate to register and utilize an Autonomous System (AS), and lists criteria for such. ASes are the unit of routing policy in the modern world of exterior routing, and are specifically applicable to protocols like EGP (Exterior Gateway Protocol, now at historical status; see [EGP]), BGP (Border Gateway Protocol, the current de facto standard for inter-AS routing; see [BGP-4]), and IDRP (The OSI Inter-Domain Routing Protocol, which the Internet is expected to adopt when BGP becomes obsolete; see [IDRP]). It should be noted that the IDRP equivalent of an AS is the RDI, or Routing Domain Identifier.

Routing high-bandwidth traffic in max-min fair share networks

Abstract: We study how to improve the throughput of high-bandwidth traffic such as large file transfers in a network where resources are fairly shared among connections. While it is possible to devise priority or reservation-based schemes that give high-bandwidth traffic preferential treatment at the expense of other connections, we focus on the use of routing algorithms that improve resource allocation while maintaining max-min fair share semantics. In our approach, routing is closely coupled with congestion control in the sense that congestion information, such as the rates allocated to existing connections, is used by the routing algorithm. To reduce the amount of routing information that must be distributed, an abstraction of the congestion information is introduced. Using an extensive set of simulation, we identify a link-cost or cost metric for "shortest-path" routing that performs uniformly better than the minimal-hop routing and shortest-widest path routing algorithms. To further improve throughput without reducing the fair share of single-path connections, we propose a novel prioritized multi-path routing algorithm in which low priority paths share the bandwidth left unused by higher priority paths. This leads to a conservative extension of max-min fairness called prioritized multi-level max-min fairness. Simulation results confirm the advantages of our multi-path routing algorithm.

Securing the border gateway routing protocol

Abstract: We analyze the security of the border gateway routing protocol and identify a number of vulnerabilities in its design and the corresponding threats. We then present a set of proposed modifications to the protocol which minimize or eliminate the most significant threats. The innovation we introduce is the protection of the second-to-last information contained in the autonomous path attributes by the digital signatures, and the use of techniques developed for detecting loops in path-finding protocols to verify the selected route's path information. With these techniques we are able to secure full path information in near constant space, and avoid the recursive protection mechanisms previously assumed necessary.

BGP Communities Attribute

Abstract: Border Gateway Protocol [1] is an inter-autonomous system routing protocol designed for TCP/IP internets.

Fault-tolerant routing in hypercube multicomputers using local safety information

Abstract: Previous methods of making wormhole-routed meshes fault tolerant have been based on adding virtual channels to the networks. This paper proposes an alternative method, one based on the turn model for designing wormhole routing algorithms. The turn model produces routing algorithms that are deadlock free, very adaptive, minimal or nonminimal, and livelock free for direct networks--whether or not they contain virtual channels. This paper illustrates how to modify the routing algorithms produced by the turn model to handle dynamic faults. This paper first describes how to modify the negative-first routing algorithm, which the turn model produces for n-dimensional meshes without virtual channels, to make it one-fault tolerant. Simulations of the one-fault-tolerant routing algorithm and other minimal and nonminimal routing algorithms in a two-dimensional mesh indicate that misrouting increases communication latencies significantly at high throughputs. The conclusion is that misrouting should be used only for increasing the degree of fault tolerance, never for just increasing adaptiveness. Finally , the paper describes how to modify the negative-first routing algorithm to make it (n - 1)-fault tolerant for n-dimensional meshes without virtual channels.

Automatic layout standard cell routing

Abstract: A method of interconnecting transistors and other devices in order to optimize area of a layout of a cell while honoring performance constraints (1502) and enhancing yield starts with a prerouting step (152) that routes adjacent transistors using diffusion wiring (1506), routes power and ground nets (1508), routes aligned gates (1510), routes all remaining aligned source/drain nets as well as any special nets (1512). Next, all of the remaining nets are routed using an area based router (1408). Nets are order based on time criticality or net topology (1602). A routing grid is assigned for all the layers to be used in routing (1604). An initial coarse routing is performed (1606). Wire groups are assigned to routing layers (1608). Routing is improved and vias are minimized (1610). A determination is then made whether the routing solution is acceptable (1612). If the routintg solution is not acceptable, the routing space is expanded and routing costs and via costs are modifyied to improve the routing solution. Finally, the best routing solution is picked (1414).

Virtual trees routing protocol for an ATM-based mobile network

Abstract: The present invention is a system and method for routing cells in a wireless communications network, wherein the communications network includes a plurality of switching nodes and the cells are routed according to destination-rooted virtual path identifier (VPI) trees. The present invention includes a routing protocol for determining preestablished VPI trees rooted at each destination node. The routing protocol manages the routes of these trees, while ensuring that there are at least two VPI trees from each source to each destination for reliability reasons, and that each destination node has multiple VPI trees for load-balancing reasons. The routing protocol includes an off-line procedure for the determination of the initial VPI trees. In order to handle changes in network traffic and conditions, the routing protocol updates the routes of the VPI trees in a dynamic and distributed fashion. These update procedures are triggered by congestion, link/node failures and link/node additions.

Emergency mobile routing protocol

Abstract: An emergency routing protocol within a wireless communication network. A mobile device can establish a communication link to the system backbone even when, for whatever reason, it can no longer communicate directly with a base station. The emergency routing protocol enables a distressed mobile device to communicate with the system backbone through another mobile device serving as an intermediary. The intermediary mobile device forwards information destined to/received from the distressed mobile device to its intended destination.

Digital signature protection of the OSPF routing protocol

Abstract: The routing protocols used to disseminate routing information throughout the Internet are not protected from intruders or faulty router participants. This paper reports on work in progress to protect the OSPF routing protocol through the use of cryptography, specifically, digital signatures. The routing information is signed with an asymmetric cryptographic algorithm, allowing each router recipient to check the source and integrity of the information. This paper discusses the fundamental issues in security of routing protocols, reviews the basics of OSPF operation, describes the proposed design and discusses remaining vulnerabilities.

Method of automatic updating and use of routing information by programmable and manual routing information configuration based on least lost routing

Abstract: In an electronic messaging system which has multiple sites, and in which each site is defined by a unique address space and has connectivity to at least one other site, messages are sent by receiving at a first site message routing information from a second site. The message routing information defines routes from the second site to one or more of the plurality of sites. The received message routing information is assimilated into previously known routing information to generate an updated accumulation of routing information. The updated accumulation of routing information is used to route messages to one or more of the plurality of sites. The updated accumulation of routing information may be replicated to still other sites in the messaging system, which in turn assimilate the information into their respective collections of known routing information. This process of receiving, assimilating and replicating may be repeated until each of the sites has substantially the same updated accumulation of routing information.

Adaptive routing in irregular networks using cut-through switches

Abstract: Many cut-through switches, which can greatly reduce network latency, are commercially available for the construction of high-speed local area networks. The interconnection of cut-through switches provides an excellent network platform for high-performance workstation clusters. A novel deadlock-free adaptive routing algorithm is proposed to allow irregular interconnection of cut-through switches. The adaptive routing algorithm is based on two unidirectional adaptive trails constructed from two opposite unidirectional Eulerian trails. Some heuristics are suggested in terms of the selection of Eulerian trails, the avoidance of long routing paths, and the degree of adaptivity. Extensive simulation experiments based on a more realistic finite input source model are conducted to evaluate the network performance under different network parameters and traffic conditions. Both bimodal and bursty messages are considered. Such switch-based irregular networks are truly incrementally scalable and have potential to be reconfigured to adapt to the dynamics of network traffic conditions.

Congestion-oriented shortest multipath routing

Abstract: We present a framework for the modeling of multipath routing in connectionless networks that dynamically adapt to network congestion. The basic routing protocol uses a short-term metric based on hop-by-hop credits to reduce congestion over a given link, and a long-term metric based on end-to-end path delay to reduce delays from a source to a given destination. A worst-case bound on the end-to-end path delay is derived under three architectural assumptions: each router adopts weighted fair queueing (or packetized generalized processor sharing) service discipline on a per destination basis, a permit-bucket filter is used at each router to regulate traffic flow on a per destination basis, and all paths are loop free. The shortest multipath routing protocol regulates the parameters of the destination-oriented permit buckets and guarantees that all portions of a multipath are loop free.

Universal algorithms for store-and-forward and wormhole routing

Abstract: In this paper we present routing algorithms that are tmiversal in the sense that they route messages along arbitrary (simple) paths in arbitrary networks. The algorithms are analyzed in terms of the number of messages being routed, the maximum number of messages that must cross any edge in the network (edge congestion), the maximum number of edges that a message must cross (dilation), the bufler size, and the bandwidth of the links. We present two main results, both of which have applications to ttnivexsal storeand-forwwd routing and universal wormhole routing. Our results yield significant performance improvements over all previously known universal routing algorithms for a wide range of parameters, and they even improve many time bounds for standard networks. In addition, we present adaptations of our main results for routing along shortest paths in arbitrary networks, and for routing in leveled networks, node-symmetric networks, edge-symmetric networks, expanders, butterflies, and meshes.

Snapshot routing with route aging

Abstract: A method and system for maintaining and updating routing information in a packet switching network for a set of quasidynamic routes, in which intermittent routing updates are permitted, so that routes are no longer "always static" or "always dynamic", but may change over time between static and dynamic, and are treated accordingly. The invention is particularly applicable to dial-on-demand serial communication links, but is also useful in any situation where it is desired to reduce the overhead from routing updates over a communication link, or where transmission over a communication link is not reliable. A protocol manager for a dynamic routing protocol is modified to determine, for each route, (1) whether to send updated routing information for that route (at the time it would otherwise send an up-date for a particular route), and (2) whether to age that route in its routing tables (at the time it would otherwise age that route). The modified protocol manager thus prevents automatic aging of routes, while avoiding the use of manually configured static routing tables. Routing information is thus learned automatically and dynamically at appropriate times, and refreshed periodically so that it eventually reflects actual changes to the network topology.

Adaptive source routing in multistage interconnection networks

Abstract: We describe the adaptive source routing (ASR) method which is a first attempt to combine adaptive routing and source routing methods. In ASR, the adaptivity of each packet is determined at the source processor. Every packet can be routed in a fully adaptive or partially adaptive or non-adaptive manner, all within the same network at the same time. We evaluate and compare performance of the proposed adaptive source routing networks and oblivious routing networks by simulations. We also describe a route generation algorithm that determines maximally adaptive routes in multistage networks.

Universal continuous routing strategies

Abstract: We analyze universal routing protocols, that is, protocols that can be used for any communication pattern in any network, under a stochastic model of continuous message generation. In particular, we present two universal protocols, a store-and-forward and a wormhole routing protocol, and characterize their performance by the following three parameters: the maximum message generation rate for which the protocol is stable, the expected delay of a message from generation to service, and the time the protocol needs to recover from worst-case scenarios. Both protocols yield significant performance improvements over all previously known continuous routing protocols. In addition, we present adaptations of our protocols to continuous routing in node-symmetric networks, butterflies, and meshes.

Congestion control in asynchronous, high-speed wormhole routing networks

Abstract: High-speed networks use lightweight protocols and a simple switch architecture for achieving higher speeds. A lightweight switching technique for local area and campus environments is wormhole routing, in which the head of a packet (worm), upon arriving at an intermediate switch, is immediately forwarded to the next switch on the path. Thus, the packet, like a worm, may stretch across several intermediate switches and links. Wormhole routing networks provide low latency. However, they are particularly prone to congestion, thus requiring careful flow control. The authors consider high-speed, asynchronous, unslotted wormhole routing networks. For such networks, two different flow control mechanisms are compared and contrasted, namely, backpressure flow control and deflection routing (with local input rate control). With backpressure, in order to maintain deadlock-free routing, either up/down routing or shortest path routing with virtual channels is assumed. With deflection routing, to avoid livelocks, worm alignment (delayed deflection) is performed at the switches. It is shown via simulation that the throughput performance of the two schemes is comparable (except for up/down routing). The authors also discuss the tradeoffs with respect to the complexity of hardware, routing protocols and buffer requirements. The authors further examine the role of input rate control at the hosts to overcome unbounded delays typical of deflection routing, and show it is possible to achieve lower average number of hops and transit delays by employing suitable input rate control policies.

Optimal routing tables

Abstract: Jaap-Henk Hoepman Paul Vitfinyi (2WI CWI and University of Amsterdam v # u an edge incident to u on a path from u to v. This way, The optimal space used to represent routing schemes in communication networks is established, both for worst-case static networks and on the average for all static networks. Several factors may influence the cost of representing a routing scheme for a particular network. It is therefore unavoidable that we first describe several reasonable models in which to measure this cost. Failure to do so in the past has obfuscated previous results. We show that, in most models, for almost all graphs @(nz) bits are necessary and sufficient for shortest path routing. By ‘almost all graphs’ we mean the Kolmogorov random graphs which constitute a fraction of 1 – l/nc of all graphs on n nodes, where c ~ 3 is an arbitrary fixed constant. In contrsat, there is a model that rises the average case lower bound to $2(n2 log n) and another model where the average case upper bound drops to O(n logz n). This clearly exposes the sensitivity of such bounds to the model under consideration. Furthermore, if paths have to be short, but need not be shortest (i.e., if the stretch factor may be larger than 1), our other upper bounds indicate that much less space is needed on average, even in the more demanding models. For worst-case static networks we prove a f2(n2 log n) lower bound for shortest path routing, for those models where the nodes in the network are labelled 1,. ... n. This lower bound holds even for all stretch factors <2. Throughout, we use the incompressibility method baaed on Kolmogorov complexity.

Fault-tolerant routing strategy using routing capability in hypercube multicomputers

Abstract: This paper addresses fault-tolerant routing which is concerned with finding feasible minimum paths in a faulty hypercube. The concept of routing capability, which is defined with respect to the entire spectrum of distance, is proposed to assist routing function. The amount of information that is useful for message routing is increased with our scheme. The proposed algorithm routes a message in an attempt to minimize derouting. In particular, it makes use of the information embedded in routing capabilities to establish a path for a message for which an upper bound on its length may be determined at the source. We then propose the notion of directed routing capability which captures more useful information for shortest path routing in comparison with undirected counterpart. Routing in hypercubes with link failures is also addressed.

A bounded-hop-count deflection scheme for Manhattan-street networks

Abstract: We present a deflection method suitable for Manhattan-street networks (MSN), which, without dropping packets, limits the number of hops travelled by a packet on its way from source to destination. The proposed routing scheme is intended for bidirectional networks-with four incoming and four outgoing links per switch. In terms of average performance measures, our method performs no worse than the best local routing schemes, when the offered load is light or moderate. Unlike other deflection schemes proposed for MSN, our method is inherently asynchronous. This simplifies the switch design and eliminates some problems with the original synchronous approach, like the need to account for slight discrepancies in transmission rates of different switches.

Performance comparisons of two retransmission protocols for CDMA

Abstract: We describe a new radio link protocol for CDMA IS-95 circuit-mode data. This protocol, (Protocol S), relies on a single level of recovery and uses a flexible segmentation and recovery (FSAR) sublayer to efficiently pack data frames into physical layer bursts. We next describe Protocol T, that consists of two levels of recovery and compare the performance of Protocol T with Protocol S. Protocol T has been standardized for CDMA circuit-mode data as IS-99. We find that the complexity of the two level recovery mechanism buys higher throughput through reduced overhead. However, the choice of TCP (and its associated congestion control mechanism) as the upper layer of recovery on the link layer, leads to long fade recovery times for Protocol T.

Routing multimedia packets in a frequency-hop packet radio network

Abstract: A new method is described for routing multimedia traffic in a frequency-hop (FH) store-and-forward packet radio network. The method is illustrated for traffic of two types, each type having its own throughput, delay, and error-rate requirements. A typical application is the routing of voice and data packets in a multi-hop network. In such an application, the voice packets cannot tolerate much delay, but they are allowed to contain a small number of errors, while the data packets must be delivered error-free even if a moderate delay is required to do so. The routing protocol presented in the paper takes into account the type of service required for each type of traffic. In addition, the routing protocol adapts to the interference as seen by the FH radios in the network. The approach is based on least-resistance routing with different link and path resistance metrics for different message types. The link resistance metrics reflect the ability of a radio to receive a packet on the link and the ability of the link to accommodate the service required by the type of packet that is being transmitted. The route chosen for a particular type of packet depends on the ability of the radios along the route to receive and forward the packet within the constraints imposed by its service requirements.

Ordered Core Based Trees

Abstract: : This thesis presents a new protocol, the Ordered Core Based Tree (OCBT) protocol, which remedies several shortcomings of the Core Based Tree (CBT) multicast protocol. The CBT protocol can form loops during periods of routing instability, and it can fail to consistently build a connected multicast tree, even when the underlying routing is stable. The OCBT protocol provably eliminates these deficiencies and reduces the latency of tree repair following a link or core failure. OCBT also improves scalability by allowing exible placement of the cores that serve as points of connection to a multicast tree. Simulation results show that the amount of control traffic in OCBT is comparable to that in CBT.

A foundation for designing deadlock-free routing algorithms in wormhole networks

Abstract: This paper provides necessary and sufficient conditions for deadlock-free unicast and multicast routing with the path-based routing model in interconnection networks which use the wormhole switching technique. The theory is developed around three central concepts: channel waiting, false resource cycles, and valid destination sets. The first two concepts are suitable extensions to those developed for unicast routing by two authors of this paper; the third concept has been developed by Lin and Ni. The necessary and sufficient conditions can be applied in a straightforward manner to prove deadlock freedom and to find more adaptive routing algorithms for collective communication. The latter point is illustrated by developing two routing algorithms for multicast communication in 2-D mesh architectures. The first algorithm uses fewer resources (channels) than an algorithm proposed in the literature but achieves the same adaptivity. The second achieves full adaptivity for multicast routing.

Artificial intelligence search techniques as fault-tolerant routing strategies

Abstract: Most fault-tolerant routing strategies are topology dependent or constrained to tolerate specific classes of faults. Artificial Intelligence search techniques, on the other hand, are potentially adaptive and can be applied to a generic problem space. We investigate the performance of such search techniques modified for use as fault-tolerant routing strategies on a problem space simulating a multiprocessor network of generic topology. This virtual network comprises processors individually equipped with a communications router designed to support message routing. The performances of these modified search techniques are compared for up to 20% of randomly generated link faults (with a processor failure being simulated by total link failure). The results show that the heuristic class of search techniques are potentially suitable for adaptation as fault-tolerant routing strategies on multiprocessor networks.