Showing papers on "Wireless Routing Protocol published in 1996"

Dynamic Source Routing in Ad Hoc Wireless Networks

Abstract: An ad hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. In such an environment, it may be necessary for one mobile host to enlist the aid of other hosts in forwarding a packet to its destination, due to the limited range of each mobile host’s wireless transmissions. This paper presents a protocol for routing in ad hoc networks that uses dynamic source routing. The protocol adapts quickly to routing changes when host movement is frequent, yet requires little or no overhead during periods in which hosts move less frequently. Based on results from a packet-level simulation of mobile hosts operating in an ad hoc network, the protocol performs well over a variety of environmental conditions such as host density and movement rates. For all but the highest rates of host movement simulated, the overhead of the protocol is quite low, falling to just 1% of total data packets transmitted for moderate movement rates in a network of 24 mobile hosts. In all cases, the difference in length between the routes used and the optimal route lengths is negligible, and in most cases, route lengths are on average within a factor of 1.01 of optimal.

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.

A survey of routing techniques for mobile communications networks

Abstract: Mobile wireless networks pose interesting challenges for routing system design. To produce feasible routes in a mobile wireless network, a routing system must be able to accommodate roving users, changing network topology, and fluctuat- ing link quality. We discuss the impact of node mobility and wireless communication on routing system design, and we survey the set of techniques employed in or proposed for routing in mobile wireless networks.

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.

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.

Truly seamless wireless and mobile host networking. Protocols for adaptive wireless and mobile networking

Abstract: Describes work in routing packets to mobile hosts in a large internetwork, such as the Internet, and gives an overview of implementation work in this area. The authors discuss the problem of routing in an ad hoc network of wireless mobile hosts, as might be needed in an area without established wireless networking infrastructure; they describe a new protocol developed for routing in such a network and summarize the results from a simulation of the protocol. They then describe work in providing support for adaptive operation of higher-layer protocols and applications; they have developed an inexpensive protocol and application programming interface (API) for notifying higher layers when the quality of a mobile host's network connection changes as it moves between different locations, possibly including changes in the type of network in use at each location. Finally, they compare their work to related mobile networking research elsewhere and present conclusions.

Wireless ATM and Ad-Hoc Networks: Protocols and Architectures

Abstract: From the Publisher: ATM is regarded as the next high speed multimedia networking paradigm. Mobile computing, which is a confluence of mobile communications, computing and networks, is changing the way people work. Wireless ATM combines wireless and ATM technologies to provide mobility support and multimedia services to mobile users. Wireless ATM and Ad-Hoc Networks: Protocols and Architectures, a consolidated reference work, presents the state of the art in wireless ATM technology. It encompasses the protocol and architectural aspects of Wireless ATM networks. The topics covered in this book include: mobile communications and computing, fundamentals of ATM and Wireless ATM, mobile routing and switch discovery, handover protocol design and implementation, mobile quality of service, unifying handover strategy for both unicast and multicast mobile connections, and roaming between Wireless ATM LANs. A novel routing protocol for ad-hoc mobile networks (also known as Cambridge Ad-hoc) is also presented in this book along with information about ETSI HIPERLAN, the RACE Mobile Broadband System, and SUPERNET. This timely book is a valuable reference source for researchers, scientists, consultants, engineers, professors and graduate students working in this new and exciting field.

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.

Efficient routing in optical networks

Abstract: This paper studies the problem of dedicating routes to connections in optical networks. In optical networks, the vast bandwidth available in an optical fiber is utilized by partitioning it into several channels, each at a different optical wavelength. A connection between two nodes is assigned a specific wavelength, with the constraint that no two connections sharing a link in the network can be assigned the same wavelength. This paper considers optical networks with and without switches, and different types of routing in these networks. It presents optimal or near-optimal constructions of optical networks in these cases and algorithms for routing connections, specifically permutation routing for the networks constructed here.

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.

A fault-tolerant routing strategy in hypercube multicomputers

Abstract: We investigate fault-tolerant routing which aims at finding feasible minimum paths in a faulty hypercube. The concept of unsafe node and its extension are used in our scheme. A set of stringent criteria is proposed to identify the possibly bad candidates for forwarding a message. As a result, the number of such undesirable nodes is reduced without sacrificing the functionality of the mechanism. Furthermore, the notion of degree of unsafeness for classifying the unsafe nodes is introduced to facilitate the design of efficient routing algorithms which rely on having each node keep the states of its nearest neighbors. We show that a feasible path of length no more than the Hamming distance between the source and the destination plus four can always be established by the routing algorithm as long as the hypercube is not fully unsafe. The issue of deadlock freeness is also addressed in this research. More importantly, another fault-tolerant routing algorithm, which requires only a constant of five virtual networks in wormhole routing to ensure the property of deadlock freeness for a hypercube of any size, is presented in this paper.

Memory requirement for routing in distributed networks

Abstract: In this paper, we deal with the compact routing problem on distributed networks, that is implementing routing schemes that use a minimum memory size on each node. We prove that for every shortest path routing scheme, for any constant e, O < c < 1, and for every integer d such that 3 ~ d < En, there exists a n-node network of maximum degree d that locally requires @(n log d) bits of memory on El(n) nodes. This optimal lower bound means that whatever you choose the routing scheme (interval routing, boolean routing, prefix routing, . ..). there exists a network on which one can not do better than routing tables.

Multicast routing for real-time communication of high-speed networks

Abstract: Real-time network applications, e.g., multimedia applications and critical control applications, are evolving at a fast pace. These applications are resource-intensive, have stringent delay requirements, and in many cases involve more than two participants. Efficient multicast communication mechanisms are, therefore, necessary to support real-time applications. In this dissertation, we study five routing problems for real-time communication on high-speed connection-oriented wide-area networks. The objective of all problems we study is to optimize the utilization of the network resources without violating the delay requirements of real-time applications. We focus primarily on multicast routing problems, but we consider also the special cases of broadcast routing and unicast routing.

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.

Performance comparison of static routing and dynamic routing in low-Earth orbit satellite networks

Abstract: We compare the performance of two routing schemes for LEO satellite networks through simulation. The two routing schemes represent static and dynamic routing for the case where the LEO satellite network is modeled as a finite state automaton (FSA). Each state in this FSA modeling corresponds to an equal-length interval within the period of the LEO satellite network. Modeling the LEO satellite network in this way allows us to consider the LEO satellite network as if it is a fixed topology network within each state. The routing table for the static routing is fixed within each state whereas that for the dynamic routing is updated continuously according to the shortest-path algorithm. The simulation results show that the static routing performs better in terms of newly initiated call blocking than the dynamic one. The results also show that the static routing gives lower ongoing call blocking probabilities than the dynamic counterpart since the former's pre-computed routing table is less susceptible to the abrupt topological change during a state transition.

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.

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.

Analysis of adaptive routing schemes in multirate loss networks

Abstract: As technology evolves, it is now feasible to implement sophisticated adaptive routing schemes on networks which support different kinds of services with heterogeneous bandwidth characteristics. Adaptive routing can increase the network throughput by routing calls to less congested paths. It can also be used to bypass transmission facility failures. In this paper, we analyze and compare two adaptive routing schemes. The first is called theMaximum mean time to blocking (MTB) routing which is based on themean time to blocking measure of a link. This measure captures the traffic rates, bandwidth characteristic and link capacity information and reflects more accurately the congestion status of different paths. The second is theM 2 routing, which is a modification of the least loaded routing (LLR). Aggregation of link status information can significantly reduce signalling traffic. We show in this paper that with properly designed aggregation, the aggregatedM 2 and MTB routings can have performance that approach that of the non-aggregated schemes. The use of complete sharing and restricted access policies together with trunk reservation control in multirate loss networks are also studied.

Adaptive techniques for routing and wavelength assignment in all-optical WANs

Abstract: This paper considers routing and wavelength assignment issues in wavelength-routed all-optical networks. We use a general approach in which all paths connecting a source-destination pair are taken as candidate paths and the network state information is incorporated into the routing process. We formulate the optimal routing problem as an integer linear programming problem and show that it is computationally intractable. We then present adaptive routing and wavelength assignment algorithms and evaluate their blocking performance. Computational complexity of these algorithms is also analyzed. Simulation results are compared with analytical predictions of the call blocking probability.

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 issues in mobile wireless networks

Abstract: The research presented in this thesis deals with the following performance issues in mobile wireless networks: recovery, location management and routing. The mobile wireless environment poses challenging fault-tolerant data management problems due to the mobility of the users, limited bandwidth on the wireless link, and power restrictions on the mobile hosts. Thus, traditional fault-tolerance schemes cannot be directly applied to these systems. To this effect, extensions to existing traditional recovery schemes are presented which suit this environment. Analytical models are built to analyze the performance of these schemes to determine those environments where a particular recovery scheme is best suited. The trade-off parameters to evaluate the recovery scheme are identified. It is determined that in addition to the failure rate of the host, the performance of a recovery scheme depended on the mobility of the hosts and the wireless bandwidth. In order to communicate with a user, one needs to know their location. The network thus faces a problem of continuously keeping track of the location of every user. An important issue in mobile wireless networks is the design and analysis of location management schemes. This thesis presents the design and analysis of centralized and distributed location management schemes. Significant performance improvements are obtained over existing protocols. Dynamic mobile wireless networks consist of mobile hosts which can communicate with each other over the wireless links (direct or indirect) without any static network interaction. In such networks the mobile host has the capability to communicate directly with another mobile host in its vicinity. The mobile hosts also have the capability to forward (relay) packets. The problem in hand is the complexity of updating the routing information in such a dynamic network. The dynamism in the network is due to host mobility, and disconnections. This thesis presents a cluster-based methodology for routing in such dynamic networks. Algorithms for cluster creation and maintenance are presented and analyzed. Compared to existing and conventional routing protocols, the proposed cluster-based approach incurs lower overhead during topology updates and also provides quicker reconvergence.

An optimal routing policy for mesh-connected topologies

Abstract: We present a new routing policy, called maximum shortest paths (MP) routing policy, within the class of shortest-path routing policies for mesh-connected topologies which include popular 2-D and 3-D meshes, 2-D and 3-D tori, and n-dimensional hypercubes (n-cubes). In this policy, the routing message is always forwarded to a neighbor from which there exists a maximum number of shortest paths to the destination. An optimal routing defined in this paper is the one that maximizes the probability of reaching the destination from a given source without delays at intermediate nodes. We show that the MP routing policy is equivalent to the e-cube routing in n-cubes which is optimal, and it is also equivalent to the Badr and Podar's zig-zag (Z/sup 2/) routing policy in 2-D meshes which is also optimal. We prove that the Z/sup 2/ routing policy is not optimal in any N/spl times/N torus, where N is an even number larger than four. A routing algorithm is proposed to implement the MP routing policy in 2-D tori and if is proved to be at least suboptimal (optimal for some cases). Our approach is the first attempt to address optimal routing in the torus network which is still an open problem.