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Showing papers on "Hazy Sighted Link State Routing Protocol published in 2003"


01 Oct 2003
TL;DR: The Optimized Link State Routing protocol is an optimization of the classical link state algorithm tailored to the requirements of a mobile wireless LAN and provides optimal routes (in terms of number of hops).
Abstract: This document describes the Optimized Link State Routing (OLSR) protocol for mobile ad hoc networks. The protocol is an optimization of the classical link state algorithm tailored to the requirements of a mobile wireless LAN. The key concept used in the protocol is that of multipoint relays (MPRs). MPRs are selected nodes which forward broadcast messages during the flooding process. This technique substantially reduces the message overhead as compared to a classical flooding mechanism, where every node retransmits each message when it receives the first copy of the message. In OLSR, link state information is generated only by nodes elected as MPRs. Thus, a second optimization is achieved by minimizing the number of control messages flooded in the network. As a third optimization, an MPR node may chose to report only links between itself and its MPR selectors. Hence, as contrary to the classic link state algorithm, partial link state information is distributed in the network. This information is then used for route calculation. OLSR provides optimal routes (in terms of number of hops). The protocol is particularly suitable for large and dense networks as the technique of MPRs works well in this context.

5,442 citations


Journal ArticleDOI
11 May 2003
TL;DR: This work proposes security goals for routing in sensor networks, shows how attacks against ad-hoc and peer-to-peer networks can be adapted into powerful attacks against sensors, and introduces two classes of novel attacks against sensor networks sinkholes and HELLO floods.
Abstract: We consider routing security in wireless sensor networks. Many sensor network routing protocols have been proposed, but none of them have been designed with security as a goal. We propose security goals for routing in sensor networks, show how attacks against ad-hoc and peer-to-peer networks can be adapted into powerful attacks against sensor networks, introduce two classes of novel attacks against sensor networks sinkholes and HELLO floods, and analyze the security of all the major sensor network routing protocols. We describe crippling attacks against all of them and suggest countermeasures and design considerations. This is the first such analysis of secure routing in sensor networks.

2,946 citations


Proceedings ArticleDOI
15 Sep 2003
TL;DR: A novel randomized network coding approach for robust, distributed transmission and compression of information in networks is presented, and its advantages over routing-based approaches are demonstrated.
Abstract: A novel randomized network coding approach for robust, distributed transmission and compression of information in networks is presented, and its advantages over routing-based approaches is demonstrated.

1,171 citations


Journal ArticleDOI
01 Jul 2003
TL;DR: The Secure Efficient Ad hoc Distance vector routing protocol (SEAD) is designed and evaluated, a secure ad hoc network routing protocol based on the design of the Destination-Sequenced Distance-Vector routing protocol that performs well over the range of scenarios and is robust against multiple uncoordinated attackers creating incorrect routing state in any other node.
Abstract: An ad hoc network is a collection of wireless computers (nodes), communicating among themselves over possibly multihop paths, without the help of any infrastructure such as base stations or access points. Although many previous ad hoc network routing protocols have been based in part on distance vector approaches, they have generally assumed a trusted environment. In this paper, we design and evaluate the Secure Efficient Ad hoc Distance vector routing protocol (SEAD), a secure ad hoc network routing protocol based on the design of the Destination-Sequenced Distance-Vector routing protocol. In order to support use with nodes of limited CPU processing capability, and to guard against Denial-of-Service attacks in which an attacker attempts to cause other nodes to consume excess network bandwidth or processing time, we use efficient one-way hash functions and do not use asymmetric cryptographic operations in the protocol. SEAD performs well over the range of scenarios we tested, and is robust against multiple uncoordinated attackers creating incorrect routing state in any other node, even in spite of any active attackers or compromised nodes in the network.

844 citations


Proceedings ArticleDOI
27 Jan 2003
TL;DR: The proposed secure link state routing protocol (SLSP) provides secure proactive topology discovery, which can be beneficial to network operation in a number of ways.
Abstract: Secure operation of the routing protocol is one of the major challenges to be met for the proliferation of the mobile ad hoc networking (MANET) paradigm. Nevertheless, security enhancements have been proposed mostly for reactive MANET protocols. The proposed secure link state routing protocol (SLSP) provides secure proactive topology discovery, which can be beneficial to network operation in a number of ways. SLSP can be employed as a stand-alone protocol, or fit naturally into a hybrid routing framework, when combined with a reactive protocol. SLSP is robust against individual attackers, is capable of adjusting its scope between local and network-wide topology discovery, and is capable of operating in networks of frequently changing topology and membership.

501 citations


Journal ArticleDOI
01 Jan 2003
TL;DR: Experimental evidence from two wireless test-beds shows that there are usually multiple minimum hop-count paths, many of which have poor throughput, and suggests that more attention be paid to link quality when choosing ad hoc routes.
Abstract: Existing wireless ad hoc routing protocols typically find routes with the minimum hop-count. This paper presents experimental evidence from two wireless test-beds which shows that there are usually multiple minimum hop-count paths, many of which have poor throughput. As a result, minimum-hop-count routing often chooses routes that have significantly less capacity than the best paths that exist in the network. Much of the reason for this is that many of the radio links between nodes have loss rates low enough that the routing protocol is willing to use them, but high enough that much of the capacity is consumed by retransmissions. These observations suggest that more attention be paid to link quality when choosing ad hoc routes; the paper presents measured link characteristics likely to be useful in devising a better path quality metric.

461 citations


Proceedings ArticleDOI
09 Jul 2003
TL;DR: Simulation studies using the proposed extensible on-demand power management framework with the dynamic source routing protocol show a reduction in energy consumption near 50% when compared to a network without power management under both long-lived CBR traffic and on-off traffic loads, with comparable throughput and latency.
Abstract: Battery power is an important resource in ad hoc networks. It has been observed that in ad hoc networks, energy consumption does not reflect the communication activities in the network. Many existing energy conservation protocols based on electing a routing backbone for global connectivity are oblivious to traffic characteristics. In this paper, we propose an extensible on-demand power management framework for ad hoc networks that adapts to traffic load. Nodes maintain soft-state timers that determine power management transitions. By monitoring routing control messages and data transmission, these timers are set and refreshed on-demand. Nodes that are not involved in data delivery may go to sleep as supported by the MAC protocol. This soft state is aggregated across multiple flows and its maintenance requires no additional out-of-band messages. We implement a prototype of our framework in the ns-2 simulator that uses the IEEE 802.11 MAC protocol. Simulation studies using our scheme with the dynamic source routing protocol show a reduction in energy consumption near 50% when compared to a network without power management under both long-lived CBR traffic and on-off traffic loads, with comparable throughput and latency. Preliminary results also show that it outperforms existing routing backbone election approaches.

299 citations


Proceedings ArticleDOI
09 Jul 2003
TL;DR: The results reveals that in comparison with general single-path routing protocol, multipath routing mechanism creates more overheads but provides better performance in congestion and capacity provided that the route length is within a certain upper bound which is derivable.
Abstract: Research on multipath routing protocols to provide improved throughput and route resilience as compared with single-path routing has been explored in details in the context of wired networks. However, multipath routing mechanism has not been explored thoroughly in the domain of ad hoc networks. In this paper, we analyze and compare reactive single-path and multipath routing with load balance mechanisms in ad hoc networks, in terms of overhead, traffic distribution and connection throughput. The results reveals that in comparison with general single-path routing protocol, multipath routing mechanism creates more overheads but provides better performance in congestion and capacity provided that the route length is within a certain upper bound which is derivable. The analytical results are further confirmed by simulation.

287 citations


Proceedings ArticleDOI
09 Jul 2003
TL;DR: A new algorithm for routing of messages in ad-hoc networks where the nodes are energy-constrained achieves a logarithmic competitive ratio and performs better than previously proposed algorithms for other suggested metrics such as network lifetime maximization.
Abstract: A new algorithm for routing of messages in ad-hoc networks where the nodes are energy-constrained is presented. The routing objective is to maximize the total number of messages that can be successfully sent over the network without knowing any information regarding future message arrivals or message generation rates. From a theoretical perspective, we show that if admission control of messages is permitted, then the worst-case performance of our algorithm is within a factor of O(log(network size)) of the best achievable solution. In other words, our algorithm achieves a logarithmic competitive ratio. Our approach provides sound theoretical backing for several observations that have been made by previous researchers. From a practical perspective, we show by extensive simulations that the performance of the algorithm is very good even in the absence of admission control (the admission control being necessary only to prove the competitive ratio result), and that it also performs better than previously proposed algorithms for other suggested metrics such as network lifetime maximization. Our algorithm uses a single shortest path computation, and is amenable to efficient implementation. We also evaluate by simulations the performance impact of inexact knowledge of residual battery energy, and the impact of energy drain due to dissemination of residual energy information.

237 citations


Journal ArticleDOI
TL;DR: A deterministic fault-tolerant and deadlock-free routing protocol in two-dimensional meshes based on dimension-order routing and the odd-even turn model is proposed, called extended X-Y routing.
Abstract: We propose a deterministic fault-tolerant and deadlock-free routing protocol in two-dimensional (2D) meshes based on dimension-order routing and the odd-even turn model. The proposed protocol, called extended X-Y routing, does not use any virtual channels by prohibiting certain locations of faults and destinations. Faults are contained in a set of disjointed rectangular regions called faulty blocks. The number of faults to be tolerated is unbounded as long as nodes outside faulty blocks are connected in the 2D mesh network. The extended X-Y routing can also be used under a special convex fault region called an orthogonal faulty block, which can be derived from a given faulty block by activating some nonfaulty nodes in the block. Extensions to partially adaptive routing, traffic and adaptivity-balancing using virtual networks, and routing without constraints using virtual channels and virtual networks are also discussed.

225 citations


Proceedings ArticleDOI
06 Jan 2003
TL;DR: Heuristics that allow OLSR to find the maximum bandwidth path are developed, and it is proved that for the ad-hoc network model, two of the heuristics are indeed optimal (i.e., guarantee that the highest-bandwidth path between any two nodes is found).
Abstract: In an ad-hoc network, all communication is done over wireless media, without the help of wired base stations. While many routing protocols have been developed to find and maintain routes based on a best-effort service model, quality-of-service (QoS) routing in an ad-hoc network is difficult because the network topology may change constantly and the available state information for routing is inherently imprecise. In this paper, we discuss how to support QoS routing in OLSR (optimized link state routing protocol, one of the routing protocols under study by the IETF MANET Working Group). We develop heuristics that allow OLSR to find the maximum bandwidth path, show through simulation that these heuristics do improve OLSR in the static network case, and finally, we prove that for our ad-hoc network model, two of the heuristics are indeed optimal (i.e., guarantee that the highest-bandwidth path between any two nodes is found).

01 Jan 2003
TL;DR: In this paper, the authors propose a location-aware routing protocol that is robust and works without knowledge of the existence of neighboring nodes (state-free), and compare their work against established routing protocols to demonstrate the efficacy of their solution when nodes are mobile or periodically sleep to conserve energy.
Abstract: Wireless Sensor Networks (WSNs) are being designed to solve a gamut of interesting real-world problems. Limitations on available energy and bandwidth, message loss, high rates of node failure, and communication restrictions pose challenging requirements for these systems. Beyond these inherent limitations, both the possibility of node mobility and energy conserving protocols that power down nodes introduce additional complexity to routing protocols that depend on up to date routing or neighborhood tables. Such state-based protocols suffer excessive delay or message loss, as system dynamics require expensive upkeep of these tables. Utilizing characteristics of high node density and location awareness, we introduce IGF, a location-aware routing protocol that is robust and works without knowledge of the existence of neighboring nodes (state-free). We compare our work against established routing protocols to demonstrate the efficacy of our solution when nodes are mobile or periodically sleep to conserve energy. We show that IGF far outperforms these protocols, in some cases delivering close to 100% of the packets transmitted while alternate solutions fail to even find a path between a source and destination. Specifically, we show that our protocol demonstrates a vast improvement over prior work using metrics of delivery ratio, control overhead, and end-to-end delay.

Proceedings ArticleDOI
09 Jul 2003
TL;DR: Simulation results reveal that by using a five-packet data cache, CHAMP exhibits excellent improvement in packet delivery, outperforming AODV and DSR by at most 30% in stressful scenarios and end-to-end delay is significantly reduced while routing overhead is lower at high mobility rates.
Abstract: A mobile ad hoc network is an autonomous system of infrastructureless, multihop wireless mobile nodes. Reactive routing protocols perform well in such an environment due to their ability to cope quickly against topological changes. In this paper, we propose a new routing protocol called Caching and Multipath (CHAMP) Routing Protocol. CHAMP uses cooperative packet caching and shortest multipath routing to reduce packet loss due to frequent route breakdowns. Simulation results reveal that by using a five-packet data cache, CHAMP exhibits excellent improvement in packet delivery, outperforming AODV and DSR by at most 30% in stressful scenarios. Furthermore, end-to-end delay is significantly reduced while routing overhead is lower at high mobility rates.

Journal ArticleDOI
01 Jan 2003
TL;DR: This paper argues that it is also important to ensure the robustness of packet forwarding itself, and proposes a secure traceroute protocol that enables end hosts or routers to detect and locate the source of routing misbehaviors, so that appropriate action can be taken.
Abstract: Network routing is vulnerable to disruptions caused by malfunctioning or malicious routers that draw traffic towards themselves but fail to correctly forward the traffic. The existing approach to addressing this problem is to secure the routing protocol by having it validate routing updates, i.e., verify their authenticity, accuracy, and/or consistency. In this paper, we argue that it is also important to ensure the robustness of packet forwarding itself. To this end, we propose a different approach, the central idea of which is a secure traceroute protocol that enables end hosts or routers to detect and locate the source of (arbitrarily severe) routing misbehaviors, so that appropriate action can be taken.

Proceedings ArticleDOI
09 Jul 2003
TL;DR: A deflection routing algorithm to tackle link overload where each node makes local decisions is proposed that can be a simple and efficient way to overcome link overload, without requiring any changes to the routing protocol.
Abstract: Shortest path routing protocols may suffer from congestion due to the use of a single shortest path between a source and a destination. The goal of our work is to first understand how links become overloaded in an IP backbone, and then to explore if the routing protocol, -either in its existing form, or in some enhanced form could be made to respond immediately to overload and reduce the likelihood of its occurrence. Our method is to use extensive measurements of Sprint's backbone network, measuring 138 links between September 2000 and June 2001. We find that since the backbone is designed to be overprovisioned, link overload is rare, and when it occurs, 80% of the time it is caused due to link failures. Furthermore, we find that when a link is overloaded, few (if any) other links in the network are also overloaded. This suggests that deflecting packets to less utilized alternate paths could be an effective method for tackling overload. We analytically derive the condition that a network, which has multiple equal length shortest paths between every pair of nodes (as is common in the highly meshed backbone networks) can provide for loop-free deflection paths if all the link weights are within a ratio 1 + 1/(d- I) of each other; where d is the diameter of the network. Based on our measurements, the nature of the backbone topology and the careful use of link weights, we propose a deflection routing algorithm to tackle link overload where each node makes local decisions. Simulations suggest that this can be a simple and efficient way to overcome link overload, without requiring any changes to the routing protocol.

Journal ArticleDOI
TL;DR: A robust routing protocol, a variant of perimeter routing, which tolerates up to 40% of variation in the transmission ranges of the mobile hosts and guarantees message delivery in a connected ad hoc wireless network without the use of message flooding whenever the ratio of the maximum transmission range to the minimum transmission range is at most 2.
Abstract: Several papers considered the problem of routing in ad hoc wireless networks using the positions of the mobile hosts. Perimeter routing1, 2 gives an algorithm that guarantees delivery of messages in such networks without the use of flooding of control packets. However, this protocol is likely to fail if the transmission ranges of the mobile hosts vary because of natural or man-made obstacles. It may fail because either some connections are not considered, which effectively results in a disconnection of the network, or because some crossing connections are used, which could misdirect the message. In this paper, we describe a robust routing protocol, a variant of perimeter routing, which tolerates up to 40% of variation in the transmission ranges of the mobile hosts. More precisely, our protocol guarantees message delivery in a connected ad hoc wireless network without the use of message flooding whenever the ratio of the maximum transmission range to the minimum transmission range is at most √2. Copyright © 2003 John Wiley & Sons, Ltd.

Proceedings ArticleDOI
16 Apr 2003
TL;DR: This protocol guarantees perfect routing and optimizes the usage of the network bandwidth and takes advantage of subscription aggregation to dramatically reduce the size of the routing tables, and it fully supports dynamic subscription registrations and cancellations without impacting the routing accuracy.
Abstract: In content networks, messages are routed on the basis of their content and the interests (subscriptions) of the message consumers. This form of routing offers an interesting alternative to unicast or multicast communication in loosely-coupled distributed systems with large number of consumers, with diverse interests, wide geographical dispersion, and heterogeneous resources (e.g., CPU, bandwidth). In this paper, we propose a novel protocol for content-based routing in overlay networks. This protocol guarantees perfect routing (i.e., a message is received by all, and only those, consumers that have registered a matching subscription) and optimizes the usage of the network bandwidth. Furthermore, our protocol takes advantage of subscription aggregation to dramatically reduce the size of the routing tables, and it fully supports dynamic subscription registrations and cancellations without impacting the routing accuracy. We have implemented this protocol in the application-level routers of an overlay network to build a scalable XML-based data dissemination system. Experimental evaluation shows that the size of the routing tables remains small, even with very large populations of consumers.

Journal ArticleDOI
TL;DR: It is shown that online power-aware routing does not have a constant competitive ratio to the off-line optimal algorithm, so an approximation algorithm is developed called max –min zPmin that has a good empirical competitive ratio.
Abstract: Summary This paper discusses online power-aware routing in large wireless ad hoc networks (especially sensor networks) for applications in which the message sequence is not known. We seek to optimize the lifetime of the network. We show that online power-aware routing does not have a constant competitive ratio to the off-line optimal algorithm. We develop an approximation algorithm called max –min zPmin that has a good empirical competitive ratio. To ensure scalability, we introduce a second online algorithm for power-aware routing. This hierarchical algorithm is called zone-based routing. Our experiments show that its performance is quite good. Finally, we describe a distributed version of this algorithm that does not depend on any centralization. Copyright  2003 John Wiley & Sons, Ltd.

Patent
31 Oct 2003
TL;DR: In this article, the authors present an attribute routing scheme that routes communication packets that include objects containing network optimization parameters that are used to control the physical links in the network, which allows objects having new optimization parameters beyond the conventional network topology parameters or network link parameters to be defined and propagated throughout the network.
Abstract: A system and method for routing packets over wireless and wired networks is presented. The system employs an attribute routing scheme that routes communication packets that include objects containing network optimization parameters that are used to control the physical links in the network. The routing transport protocol is logically separated from the objects that are routed, which allows objects having new optimization parameters beyond the conventional network topology parameters or network link parameters to be defined and propagated throughout the network. Additionally, new dynamic routing objects of arbitrary size can be defined that have a customizable update period. These dynamic routing objects are propagated through the network based on their respective custom update periods. The system also includes a feature that enables exponential backoff in the custom update periods. Updates may also be linked to one another, enabling network clients to query the network for related information resulting in efficient implementation of a networking system.

Journal ArticleDOI
TL;DR: The main idea is to use a 'traffic profile' of the network, obtained by measurements or service-level agreements as a rough predictor of the future traffic distribution, to solve a multi-commodity network flow problem, whose output is used both to guide the online path-selection algorithm as well as to impose admission control.

Journal ArticleDOI
TL;DR: Two hierarchical clustering protocols that improve the scalability of ad hoc routing protocols are presented, which create a one-level clustered hierarchy across an ad hoc network, and a multi-level hierarchy which is able to dynamically adjust the depth of the hierarchy in response to the changing network topology.
Abstract: Ad hoc networks have the notable capability of enabling spontaneous networks. These networks are self-initializing, self-configuring, and self-maintaining, even though the underlying topology is often continually changing. Because research has only begun to scratch the surface of the potential applications of this technology, it is important to prepare for the widespread use of these networks. In anticipation of their ubiquity, the protocols designed for these networks must be scalable. This includes scaling to both networks with many nodes, and networks with rapidly changing topologies. This paper presents two hierarchical clustering protocols that improve the scalability of ad hoc routing protocols. The Adaptive Routing using Clusters (ARC) protocol creates a one-level clustered hierarchy across an ad hoc network, while the Adaptive Routing using Clustered Hierarchies (ARCH) protocol creates a multi-level hierarchy which is able to dynamically adjust the depth of the hierarchy in response to the changing network topology. It is experimentally shown that these protocols, when coupled with an ad hoc routing protocol, produce throughput improvements of up to 80% over the ad hoc routing protocol alone.

Proceedings ArticleDOI
Kun Tan1, Qian Zhang1, Wenwu Zhu1
01 Dec 2003
TL;DR: This work proposes a novel routing framework named shortest expected path routing (SEPR), which builds up a stochastic model of the ad hoc network and maintains it in a distributed way and proposes a new routing metric, called expected path length.
Abstract: Ad hoc communication among wireless enabled smart devices is increasingly playing an important role in coordinating distributed applications. Existing ad hoc routing algorithms usually assume the existence of end-to-end path connecting communication nodes. However, due to the power limitation, radio coverage and geography distribution of cooperating nodes, in some scenarios this assumption is unlikely to be valid. We address the issue of data routing in partially connected ad hoc networks. In this situation, data propagation is achieved via mainly pair-wise communication between any two nodes when they are in vicinity. We propose a novel routing framework named shortest expected path routing (SEPR). Instead of blindly flooding messages in the network, SEPR builds up a stochastic model of the ad hoc network and maintains it in a distributed way. A new routing metric, called expected path length, is proposed. By guiding messages flow to shortest expected path nodes, our approach dramatically reduces the number of unnecessary message copies as well as increases the message delivering rate. With a simulation, we evaluate the effectiveness and the efficiency of our approach.

Journal ArticleDOI
01 Jan 2003
TL;DR: This paper proposes a new paradigm called trajectory based forwarding (or TBF), which is a generalization of source based routing and Cartesian routing, and argues that TBF is an ideal technique for routing in dense ad-hoc networks.
Abstract: Relentless progress in hardware technology and recent advances in sensor technology, and wireless networking have made it feasible to deploy large scale, dense ad-hoc networks. These networks together with sensor technology can be considered as the enablers of emerging models of computing such as embedded computing, ubiquitous computing, or pervasive computing. In this paper, we propose a new paradigm called trajectory based forwarding (or TBF), which is a generalization of source based routing and Cartesian routing. We argue that TBF is an ideal technique for routing in dense ad-hoc networks. Trajectories are a natural namespace for describing route paths when the topology of the network matches the topography of the physical surroundings in which it is deployed which by very definition is embedded computing.We show how simple trajectories can be used in implementing important networking protocols such as flooding, discovery, and network management. Trajectory routing is very effective in implementing many networking functions in a quick and approximate way, as it needs very few support services. We discuss several research challenges in the design of network protocols that use specific trajectories for forwarding packets.

Proceedings ArticleDOI
01 Dec 2003
TL;DR: A biologically inspired algorithm is presented to route messages in mobile wireless ad-hoc networks and uses stigmergy to reduce the amount of control traffic needed to maintain a high data goodput.
Abstract: A biologically inspired algorithm is presented to route messages in mobile wireless ad-hoc networks. The principles of swarm intelligence are used to define a probabilistic algorithm for which routing through paths of maximum throughput is an emergent property. This adaptive algorithm, dubbed termite, uses stigmergy to reduce the amount of control traffic needed to maintain a high data goodput. Stigmergy is a process by which information is indirectly communicated between individuals through their environment The termite environment is the contents of all routing tables. The movement of packets is influenced at each node, and communicating nodes observe this influence to update their own tables. Strong routing robustness is achieved through the use of multiple paths; each packet is routed randomly and independently.

Journal ArticleDOI
01 Feb 2003
TL;DR: This paper presents a Geocast Adaptive Mesh Environment for Routing (GAMER) which provides geocast communication in an ad hoc network and concludes that both versions of GAMER improve the transmission accuracy significantly, without increasing the load on the network significantly, when compared to non-adaptive mesh-based geocasts routing approaches.
Abstract: This article concerns a variation on multicasting, called geocasting, for an ad hoc network. The goal of a geocast routing protocol is to deliver packets to a group of nodes that are within a specified geographical area, i.e., the geocast region. This paper presents a Geocast Adaptive Mesh Environment for Routing (GAMER) which provides geocast communication in an ad hoc network. GAMER adapts to the current network environment by dynamically changing the density of the mesh. Thus, when nodes are highly mobile, a dense mesh is created; when nodes are moving slowly, a sparse mesh is created. We compare the performance of GAMER with non-adaptive mesh-based geocast routing protocols in an ns-2 simulated ad hoc network. We also compare two versions of GAMER; one version is more active than the other in adapting to the current network environment. We conclude that both versions of GAMER improve the transmission accuracy significantly, without increasing the load on the network significantly, when compared to non-adaptive mesh-based geocast routing approaches.

Proceedings ArticleDOI
11 May 2003
TL;DR: This work modifies AODV to include the source route accumulation feature of DSR, and demonstrates how a small change to the A ODV protocol can lead to significantly improved performance results.
Abstract: Ad hoc networks meet the demands of spontaneous network set-up. They are characterized by the use of wireless links, dynamically changing topology, multi-hop connectivity and decentralized routing mechanisms and decision-making. AODV and DSR are the two most widely studied on-demand ad hoc routing protocols. Previous studies have shown limitations of these protocols in certain network scenarios. To improve the performance of AODV, we modify AODV to include the source route accumulation feature of DSR. We call this AODV with path accumulation. This protocol optimizes AODV to perform effectively in terms of routing overhead and delay during high load. The performance of the protocol is evaluated by a simulation model under a variety of network conditions. We also compare its performance with that of unmodified AODV and DSR. We demonstrate how a small change to the AODV protocol can lead to significantly improved performance results.

Patent
17 Oct 2003
TL;DR: In this paper, the authors propose a changeover module to generate a sequence of intermediate network plans, each of which modifies a preceding network state according to preceding network plan, such that a routing of at least one demand in the network changes.
Abstract: A system (10), to migrate a shortest-path-first (SPF) routed network from a first routing state to a second routing state, includes a changeover module (135) to generate a sequence of intermediate network plans, each of which modifies a preceding network state according to a preceding network plan, such that a routing of at least one demand in the network changes. The sequence of intermediate network plans migrates the network from the first routing state to the second routing state. A network controller (105) sequentially configures the network according to the sequence of intermediate network plans to migrate the network from the first routing state to the second routing state. Each intermediate network plan of the sequence configures the network to operate within at least one predetermined constraint.

Proceedings ArticleDOI
19 May 2003
TL;DR: It is found that information from external routing protocols produces significant levels of instability within OSPF, and the need for new network management tools that can incorporate information from routing protocols is highlighted.
Abstract: This paper presents the results from a detailed, experimental study of OSPF an intra-domain routing protocol, running on a mid-size regional Internet service provider. Using multiple, distributed probes running custom monitoring tools, we collected continuous protocol information for a full year. We use this data to analyze the health of the network including the amount, source, duration and periodicity of routing instability. We found that information from external routing protocols produces significant levels of instability within OSPF. We also examine the evolution of the routing topology over time, showing that short term changes are incremental and that the long term trend shows constant change. Finally, we present a set of detailed investigations into several large scale anomalies. These anomalies demonstrate the significant impact external routing protocols have on OSPF. In addition, they highlight the need for new network management tools that can incorporate information from routing protocols.

Journal ArticleDOI
01 Jul 2003
TL;DR: Each of these well known contemporary protocols aimed at securing routing in mobile wireless ad hoc networks is analyzed against requirements of ad hoc routing and in some cases identify fallibilities and make recommendations to overcome these problems.
Abstract: We discuss several well known contemporary protocols aimed at securing routing in mobile wireless ad hoc networks. We analyze each of these protocols against requirements of ad hoc routing and in some cases identify fallibilities and make recommendations to overcome these problems so as to improve the overall efficacy of these protocols in securing ad hoc routing, without adding any significant computational or communication overhead.

Proceedings ArticleDOI
20 Mar 2003
TL;DR: This testbed allows for direct comparison between mobile wireless routing protocols without affecting their routing or MAC layer protocols or inter-layer interaction and shows that such a testbed provides valuable feedback not available through simulation.
Abstract: In this paper we demonstrate a wireless 802.11 testbed. This testbed allows for direct comparison between mobile wireless routing protocols without affecting their routing or MAC layer protocols or inter-layer interaction. We have built a low cost environment to facilitate such wireless network research. The core idea is "compressing" the network and emulating mobility without actually moving the nodes. We successfully emulate the RF effects along with mobility. The viability of this test bed is checked with the help of a click implementation of the dynamic source routing protocol. Our experiences show that such a testbed provides valuable feedback not available through simulation.