Topology Discovery Research Papers - Academia.edu (original) (raw)

Knowledge of the up-to-date network topology (i.e. Layer 2 & Layer 3) is crucial for efficient network management. Issues like congestion avoidance, resource management, resource discovery, root-cause analysis and event correlation require accurate information of the topology map. Due to dynamic nature of today's IP networks, keeping track of topology information manually is a daunting task. Thus efficient algorithms for automatically discovering physical network topology are necessary. The earlier work has typically concentrated on discovering topology either using completely SNMP-MIB or ICMP echo request/reply, DNS, Trace route, etc. Our proposed algorithm does not rely totally on SNMP-MIB information as it is not usually supported by all devices in the network. Instead we propose an approach where SNMP agent should only be enabled on the routers and managed switches. Rest of the network computers/hosts need not have SNMP agent enabled. We propose an efficient algorithm not only to find available computers/hosts but also to find appropriate timeouts and delays in the network. The experimental results validate our approach, demonstrating that our algorithm discovers accurate physical topology.

- by
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- Computer Science, Information Technology, Computer Networks, Network Management

An ad hoc network is a collection of mobiles nodes that communicate via multihop wireless link. In this environment, it may be necessary to collect information about network. This information may be used in routing with QoS, topology discovery or network management. The process of data collection must be efficient and distributed in order to respect ad hoc network constraints like limited battery and bandwidth. To ensure this goal, we present an extension of the routing protocol OLSR to collect some parameters from nodes in a wireless mobile ad hoc network. The primary goal of our application called OLSRM (OLSR monitoring) is the collect of information from the network with a minimum of overhead and bandwidth consumption. In this paper, we describe the mechanism of OLSRM to facilitate autonomous and distributed monitoring of an ad hoc network and demonstrate its capability via simulation by comparing our solution with another mechanism of monitoring in the ad hoc networks: RAIC

- by Sonia Mettali
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- Network Management, Topology Discovery, Mobile Ad Hoc Network, Data Collection

An important requirement in the IP-based control of time-division multiplexing (TDM) optical transport networks is to utilize the in-built protection capabilities of synchronous optical network (SONET) unidirectional path-switched rings... more

- by Vishal Sharma
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- Optical Networking, Topology Discovery, Liquid State Machine, Optical network

For a long time, traceroute measurements combined
with alias resolution methods have been the sole way to collect
Internet router level maps. Recently, a new approach has been
introduced with the use of a multicast management tool, mrinfo,
and a recursive probing scheme. In this paper, after analyzing
advantages and drawbacks of probing approaches based on
traceroute and mrinfo, we propose a hybrid discovery tool,
MERLIN (MEasure the Router Level of the INternet), mixing
mrinfo and traceroute probes. Using a central server controlling
a set of distributed vantage points in order to increase the
exploration coverage while limiting the probing redundancy, the
purpose of MERLIN is to provide an accurate router level map
inside a targeted Autonomous System (AS). MERLIN also takes
advantage of alias resolution methods to reconnect scattered multicast components. To evaluate the performance of MERLIN, we report experimental results describing its efﬁciency in topology
exploration and reconstruction of several ASes.

- by Pietro Marchetta
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- Distributed Computing, Topology, Internet Routing Protocol, Routing protocols

Tunnels are widely used to improve security and to expand networks without having to deploy native infrastructure. They play an important role in the migration to IPv6, which relies on IPv6-in-IPv4 tunnels where native connectivity is not available; however, tunnels offer lower performance and are less reliable than native links. In this paper we introduce a number of techniques to detect, and collect information about, IPv6-in-IPv4 tunnels, and show how a known tunnel can be used as a "vantage point" to launch third-party tunnel-discovery explorations, scaling up the discovery process. We describe our Tunneltrace tool, which implements the proposed techniques, and validate them by means of a wide experimentation on the 6bone tunneled network, on native networks in Italy, the Netherlands, and Japan, and through the test boxes deployed worldwide by the RIPE NCC as part of the Test Traffic Measurements Service. We assess to what extent 6bone registry information is coherent with the actual network topology, and we provide the first experimental results on the current distribution of IPv6-in-IPv4 tunnels in the Internet, showing that even "native" networks reach more than 60% of all IPv6 prefixes through tunnels. Furthermore, we provide historical data on the migration to native IPv6, showing that the impact of tunnels in the IPv6 Internet did not significantly decrease over a 6-month period. Finally, we briefly touch on the security issues posed by IPv6-in-IPv4 tunnels, discussing possible threats and countermeasures.

- by Giuseppe DI BATTISTA
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- Distributed Computing, Routing protocols, Topology Discovery, Data Security

Internet measurement studies require availability of representative topology maps. Depending on the map resolution (e.g., autonomous system level or router level), the procedure of collecting and processing an Internet topology map involves different tasks. In this paper, we present a new task, i.e., subnet inference, to advance the current state of the art in topology collection studies. Utilizing a technique to infer the subnet relations among the routers in the resulting topology map, we identify IP addresses that are connected over the same connection medium. We believe that the successful inclusion of subnet relations among the routers will yield topology maps that are closer, at the network layer, to the sampled segments of the Internet in router level topology measurement studies.

- by Alia Hadi
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- Internet Measurement, Topology Discovery, Autonomic System, Internet Topology

Software-defined networking is a novel concept that is ported into wireless sensor networks to make them more manageable and customizable. unfortunately, the topology discovery and maintenance processes generate high overhead control packet exchange between the sensor nodes and the central controller leading to a deterioration of the network's performance. In this paper, a novel minimal overhead control traffic topology discovery and data forwarding protocol is proposed and detailed. The proposed protocol requires some changes to the topology discovery protocol implemented in SDN-WISE to improve its performance. The proposed protocol has been implemented within the IT-SDN framework for evaluation. The results show reduced overhead control traffic and increase, of about 20%, data packet delivery rate over the protocol in SDN-WISE.

- by Fred Appiah-Twum and +1
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- Wireless Sensor Networks, Energy Consumption, Topology Discovery, Software Defined Networks (SDN)

Management is an essential task for the correct behavior of networks. In this field, several aspects should be taken into account. Among them, network topology is one of the most important elements to control. This paper proposes an approach to the topology discovery based on a hybrid methodology. We propose a tool, called HyNeTD (Hybrid Network-Topology Discovery), that effectively combines active and passive measurements to discover network topologies at router level. Architectural choices are presented and discussed and some preliminary experimental results, carried out over a controlled test-bed, are given.

- by Antonio Pescape'
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- Topology, Network Management, Topology Discovery, Network Routing

Economies of scale make IEEE 802.11 an attractive technology for building wireless mesh networks (WMNs). However, the IEEE 802.11 protocol exhibits serious link-layer unfairness when used in multi-hop networks. Existing fairness solutions either do not address this problem, or require proprietary MAC protocol to provide fairness. In this paper, we argue that an ideal transport protocol should be able to achieve fairness even on top of an unfair MAC layer such as 802.11. Towards this end, we propose a co-ordinated congestion control algorithm that performs global bandwidth allocation and provides end-to-end flow-level max-min fairness 1 despite weaknesses in the MAC layer. The proposed algorithm features an advanced topology discovery mechanism that detects the inhibition of wireless communication links, and a general collision domain capacity re-estimation mechanism that effectively addresses such inhibition. Through an ns-2-based simulation study we demonstrate that the proposed algorithm substantially improves the fairness across flows, eliminates starvation problem, and simultaneously maintains a high overall network throughput.

- by Pradipta De
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- Congestion Control, Topology Discovery, Bandwidth Allocation, MAC Layer

Ethernet is becoming increasingly popular in metro and access networks due to the high bandwidth available at low cost. Nonetheless, native Ethernet lacks some features that are important for sophisticated network management; providing accurate knowledge on the physical topology is one of them. Therefore, automatic physical topology discovery in support of network management is essential in Ethernet networks. Former work either focused on Layer-3 topology discovery or only provided the active topology excluding the physical links inactivated by Rapid Spanning Tree Protocol [1]. This paper introduces a novel mechanism capable of automatically discovering the entire physical topology of Ethernet networks. Our algorithm collects information available even in low-cost offthe-shelf Ethernet switches and then calculates the physical topology of the entire network. This paper describes the method and its implementation in a testbed network for assessing the performance and the robustness of the mechanism.

- by Marcos Salvador
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- Engineering Management, Network Management, Access Networks, Topology Discovery

This paper proposes a novel routing scheme for mobile ad hoc networks (MANETs), which combines the on-demand routing capability of ad hoc on-demand distance vector (AODV) routing protocol with a distributed topology discovery mechanism using ant like mobile agents. AODV requires the actual communication to be delayed until the route is determined (found). This may not be suitable for real time data and multimedia communication applications. Ant-AODV provides high connectivity, reducing the amount of route discoveries before starting new connections. This eliminates the delay before starting actual communication for most new connections making ant-AODV routing protocol ideal for real time communication in highly dynamic networks such as MANETs. Simulation results show that the ant-AODV hybrid technique proposed is able to achieve reduced end-to-end delay as compared to conventional ant-based and AODV routing protocols. In addition, ant-AODV also provides high connectivity.

- by Chen Khong Tham
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- Multimedia Communication, Topology Discovery, Mobile Ad Hoc Network, Icon

We present a formal development in Event-B of a distributed topology discovery algorithm. Distributed topology discovery is at the core of several routing algorithms and is the problem of each node in a network discovering and maintaining information on the network topology. One of the key challenges is specifying the problem itself. Our specification includes both safety properties, formalizing invariants that should hold in all system states, and liveness properties that characterize when the system reaches stable states. We establish these by appropriately combining proofs of invariant preservation, event refinement, event convergence, and deadlock freedom. The combination of these features is novel and should be useful for formalizing and developing other kinds of semi-reactive systems, which are systems that react to, but do not modify, their environment.

- by Thái Hoàng
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- Routing, Routing algorithm, Formal methods, Topology Discovery

Abstract The 7 GHz of unlicensed spectrum in the 60 GHz band offers the potential for multiGigabit indoor wireless personal area networking (WPAN). With recent advances in the speed of silicon (CMOS and SiGe) processes, low-cost... more

Abstract—For a long time, traceroute measurements combined with alias resolution methods have been the sole way to collect Internet router level maps. Recently, a new approach has been introduced with the use of a multicast management tool, mrinfo, and a recursive probing scheme. In this paper, after analyzing advantages and drawbacks of probing approaches based on traceroute and mrinfo, we propose a hybrid discovery tool, MERLIN (MEasure the Router Level of the INternet), mixing mrinfo and traceroute probes. Using a central server controlling a set of distributed vantage points in order to increase the exploration coverage while limiting the probing redundancy, the purpose of MERLIN is to provide an accurate router level map inside a targeted Autonomous System (AS). MERLIN also takes advantage of alias resolution methods to reconnect scattered mul-ticast components. To evaluate the performance of MERLIN, we report experimental results describing its efficiency in topology explorati...

- by Benoit Donnet
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- Distributed Computing, Topology, Internet Routing Protocol, Routing protocols
- by Luca Foschini
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- Distributed Computing, Grid Computing, Computer Networks, Resource Allocation

In global grid computing, i.e. Wide Area Network (WAN) grid computing, Grid network services allow grid users or the programming environment to monitor the status of network resources and to reallocate them. Specifically, the Network Information and Monitoring Service (NIMS) provides up to date information on the grid network status. In this study two implementations of a specific NIMS component, i.e. the topology discovery service (TDS), are presented. The first implementation features a centralized broker that produces information for the consumers/users. In the second one, users are contemporarily producers and consumers of the required information. Both implementations are applicable to networks based on commercial routers without requiring any router protocol modification.

- by Luca Foschini
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- Grid Computing, Resource Allocation, Routing protocols, Topology Discovery

The 7 GHz of unlicensed spectrum in the 60 GHz band offers the potential for multiGigabit indoor wireless personal area networking (WPAN). With recent advances in the speed of silicon (CMOS and SiGe) processes, low-cost transceiver realizations in this "millimeter (mm) wave" band are within reach. However, mm wave communication links are more fragile than those at lower frequencies (e.g., 2.4 or 5 GHz) because of larger propagation losses and reduced diffraction around obstacles. On the other hand, directional antennas that provide directivity gains and reduction in delay spread are far easier to implement at mm-scale wavelengths. In this paper, we present a cross-layer modeling methodology and a novel multihop medium access control (MAC) architecture for efficient utilization of 60 GHz spectrum, taking into account the preceding physical characteristics. We propose an in-room WPAN architecture in which every link is constrained to be directional, for improved power efficiency (due to directivity gains) and simplicity of implementation (due to reduced delay spread). We develop an elementary diffraction-based model to determine network link connectivity, and define a multihop MAC protocol that accounts for directional transmission/reception, procedures for topology discovery and recovery from link blockages.

- by Sumit Singh
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- Millimeter Wave Antennas, Topology Discovery, Directional Antenna, Spectrum

- by Thái Hoàng
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- Routing, Routing algorithm, Formal methods, Topology Discovery

Among many issues to be considered in designing an ad hoc wireless sensor network the key issue that stands out is to employ an efficient weighted topology discovery algorithm based upon certain node parameters. In the paper, we have described an algorithm for weighted topology discovery which uses colors based approach to partition the network in to clusters. Each cluster has a clusterhead. The nodes internal to the cluster can directly communicate with the selected clusterhead. Clusterheads can communicate with other clusterhead directly or through defined forwarding nodes. In sensor network nodes have different characteristics. The proposed algorithm is a weighted clustering approach which takes into account the network and the properties of the sensor nodes. The algorithm defines the topology in two phases. The first phase is Information exchange phase in which the nodes exchange their resources information. In the second phase the clusters in the network are discovered. The goal of the algorithm is to minimize the number for reconfigurations and minimize the number of clusterheads which results in near optimal topology for the network. At the end evaluation of the proposed Algorithm performance is done using simulations against already described techniques. Average number of clusterheads, network lifetime and reconfigurations and other factors evaluates the proposed Algorithm in term of its Performance and highlight its significance.

- by Piero Castoldi
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- Grid Computing, Topology Discovery, Network Services, Wide Area Network

This paper describes GulfStream, a scalable distributed software system designed to address the problem of managing the network topology in a multi-domain server farm. In particular, it addresses the following core problems: topology discovery and verification, and failure detection. Unlike most topology discovery and failure detection systems which focus on the nodes in a cluster, GulfStream logically organizes the network adapters of the server farm into groups. Each group contains those adapters that can directly exchange messages. GulfStream dynamically establishes a hierarchy for reporting network topology and availability of network adapters. We describe a prototype implementation of GulfStream on a 55 node heterogeneous server farm interconnected using switched fast Ethernet.

- by German Goldszmidt
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- Cluster Computing, Topology Discovery, Multi Domain, Network Topology

There is a growing interest in discovery of internet topology at the interface level. A new generation of highly distributed measurement systems is currently being deployed. Unfortunately, the research community has not examined the problem of how to perform such measurements efficiently and in a network-friendly manner. In this paper we make two contributions toward that end. First, we show that standard topology discovery methods (e.g., skitter) are quite inefficient, repeatedly probing the same interfaces. This is a concern, because when scaled up, such methods will generate so much traffic that they will begin to resemble DDoS attacks. We measure two kinds of redundancy in probing (intra- and inter-monitor) and show that both kinds are important. We show that straightforward approaches to addressing these two kinds of redundancy must take opposite tacks, and are thus fundamentally in conflict. Our second contribution is to propose and evaluate Doubletree, an algorithm that reduc...

In the past few years, the network measurement community has been interested in the problem of internet topology discovery using a large number (hundreds or thousands) of measurement monitors. The standard way to obtain information about the internet topology is to use the traceroute tool from a small number of monitors. Recent papers have made the case that increasing the number of monitors will give a more accurate view of the topology. However, scaling up the number of monitors is not a trivial process. Duplication of effort close to the monitors wastes time by reexploring well-known parts of the network, and close to destinations might appear to be a distributed denial-of-service (DDoS) attack as the probes converge from a set of sources towards a given destination. In prior work, authors of this report proposed Doubletree, an algorithm for cooperative topology discovery, that reduces the load on the network, i.e., router IP interfaces and end-hosts, while discovering almost as ...

- by Benoit Donnet
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- Open Source, Topology Discovery, Internet Architecture, Scaling up

We present here Fun in Numbers (FinN, http://finn.cti.gr), a framework for developing pervasive applications and interactive installations for entertainment and educational purposes. Using ad hoc mobile wireless sensor network nodes as the enabling devices, FinN allows for the quick prototyping of applications that utilize input from multiple physical sources (sensors and other means of interfacing), by offering a set of programming templates and services, such as topology discovery, localization and synchronization, that hide the underlying complexity. We present the target application domains of FinN, along with a set of multiplayer games and interactive installations. We describe the overall architecture of our platform and discuss some key implementation issues of the application domains. Finally, we present the experience gained by deploying the applications developed with our platform.

- by Ioannis Chatzigiannakis
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- Emotion, New Media, Augmented Reality, Topology Discovery

Measurement and monitoring of network topologies are essential tasks in current network scenarios. Indeed, due to their utility in planning, management, security, and reliability of network infrastructures, effective and efficient approaches and tools for discovering large topologies are gaining more and more attention from both Application Service Providers and network administrators. In this paper we propose a hybrid methodology and its implementation in a software platform we called Hynetd. We present the architecture, some novel algorithms and methods adopted in the discovery chain, and a performance evaluation over two network scenarios: a small scale test-bed and a large scale MAN in the heart of Napoli (Italy). We provide experimental results confirming and improving those previously obtained by a prototype of Hynetd. In addition a comparison with a commercial tool is presented. Achieved results, in terms of accuracy, discovery time, and traffic injected, are very encouraging in both considered scenarios.

Network flows running on a wireless mesh network (WMN) may suffer from partial failures in the form of serious throughput degradation, sometimes to the extent of starvation, because of weaknesses in the underlying MAC protocol, dissimilar physical transmission rates or different degrees of local congestion. Most existing WMN transport protocols fail to take these factors into account. This paper describes the design, implementation and evaluation of a coordinated congestion control (C3L) algorithm that guarantees fair resource allocation under adverse scenarios and thus provides end-to-end max-min fairness among competing flows. The C3L algorithm features an advanced topology discovery mechanism that detects the inhibition of wireless communication links, and a general collision domain capacity re-estimation mechanism that effectively addresses such inhibition. A comprehensive ns-2-based simulation study as well as empirical measurements taken from an IEEE 802.11a-based multi-hop wireless testbed demonstrate that the C3L algorithm greatly improves inter-flow fairness, eliminates the starvation problem, and at the same time maintains high radio resource utilization efficiency.

- by Pradipta De
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- Congestion Control, Resource Allocation, Topology Discovery, Wireless Mesh Network

- by Sumit singh
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- Millimeter Wave Antennas, Topology Discovery, Directional Antenna, Spectrum

- by Thái Hoàng
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- Routing, Routing algorithm, Formal methods, Topology Discovery

The dynamics of wireless ad hoc networks as a consequence of mobility and disconnection of mobile hosts pose a number of problems in designing proper routing schemes for effective communication between any source and destination . The conventional proactive routing protocols that require to know the topology of the entire network is not suitable in such a highly dynamic environment, since the topology update information needs to be propagated frequently throughout the network. On the other hand, a demand-based, reactive route discovery procedure generates large volume of control traffic and the actual data transmission is delayed until the route is determined. Because of this long delay and excessive control traffic, pure reactive routing protocols may not be applicable to real-time communication. At the same time, pure proactive schemes are likewise not appropriate for the ad hoc network environment, as they continuously use a large portion of the network capacity to keep the routing information current.

- by Sumit Singh
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- Millimeter Wave Antennas, Topology Discovery, Directional Antenna, Spectrum

- by M. Logaras and +1
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- Topology Discovery, Pervasive Game, Application development, Wireless Sensor Network

- by John Pershing and +1
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- Cluster Computing, Topology Discovery, Multi Domain, Network Topology

In this paper we investigate how network management and routing can be appropriately combined to provide effective support to advanced network infrastructures. The work belongs to the research field dealing with network architectures in which resource management is achieved through a combination of Quality of Service mechanisms, Traffic Engineering and Monitoring.

- by Stefano Avallone
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- Network Management, Topology Discovery, Quality of Service, Network Architecture

New network management tools such as User Controled Lightpath Provisioining, UCLP 1 , have appeared to allow institutions and research centers manage their own dark fiber and wavelength networks. Early versions of UCLP have been released and its functionality has been demonstrated; but two main drawbacks have been identified: only one switch model is supported and there is no topology discovery/routing schema. The work presented in this paper overcomes these limitations.

- by Eduard Grasa
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- Network Management, Topology Discovery

We present Gradient Landmark-Based Distributed Routing (GLIDER), a novel naming/addressing scheme and associated routing algorithm, for a network of wireless communicating nodes. We assume that the nodes are fixed (though their geographic locations are not necessarily known), and that each node can communicate wirelessly with some of its geographic neighbors-a common scenario in sensor networks. We develop a protocol which in a preprocessing phase discovers the global topology of the sensor field and, as a byproduct, partitions the nodes into routable tiles-regions where the node placement is sufficiently dense and regular that local greedy methods can work well. Such global topology includes not just connectivity but also higher order topological features, such as the presence of holes. We address each node by the name of the tile containing it and a set of local coordinates derived from connectivity graph distances between the node and certain landmark nodes associated with its own and neighboring tiles. We use the tile adjacency graph for global route planning and the local coordinates for realizing actual inter-and intra-tile routes. We show that efficient loadbalanced global routing can be implemented quite simply using such a scheme.

- by walfa hidayat
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- Computer Science, Graph Theory, Combinatorics, Algebraic Topology

- by Sameh Fakhouri
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- Computer Science, Cluster Computing, Topology Discovery, Hardware

Topology discovery systems are starting to be introduced in the form of easily and widely deployed software. However, little consideration has been given as to how to perform large-scale topology discovery efficiently and in a network-friendly manner. In prior work, we have described how large numbers of traceroute monitors can coordinate their efforts to map the network while reducing their impact on routers and end-systems. The key is for them to share information regarding the paths they have explored. However, such sharing introduces considerable communication overhead. Here, we show how to improve the communication scaling properties through the use of Bloom filters to encode a probing stop set. Also, any system in which every monitor traces routes towards every destination has inherent scaling problems. W e propose capping the number of monitors per destination, and dividing the monitors into clusters, each cluster focusing on a different destination list.

- by Benoit Donnet
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- Computer Science, Traffic Management, Topology Discovery, Filter

Recently, a first step towards a highly distributed IP-level topology discovery tool has been made with the introduction of the Doubletree algorithm. Doubletree is an efficient cooperative algorithm that allows the discovery of a large portion of nodes and links in the network while strongly reducing probing redundancy on nodes and destinations as well as the amount of probes sent. In this paper, we propose to reduce more strongly the load on destinations and, more essentially, the communication cost required for the cooperation ...

- by Benoit Donnet
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- Topology Discovery, Communication Cost

The use of end-to-end multicast traffic measurements has been recently proposed as a means to infer network internal characteristics as packet link loss rate and delay. In this paper, we propose an algorithm that infers the multicast tree topology based on these end-to-end measurements. Differently from previous approaches which make only partial use of the available information, this algorithm adaptively combines different performance measures to reconstruct the topology. We establish its consistency and evaluate its accuracy through simulation. We show that in general it requires many fewer probes to correctly identify the topology than other methods.

- by Francesco Lo Presti
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- Computer Science, Statistics, Statistical Analysis, Packet Switching

- by Yasir Fayyaz
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- Wireless Sensor Networks, Topology Discovery, Ad Hoc Networks, Clustering

Advanced Switching is a new high-speed industrial standard serial interconnect. It is defined as a switching fabric architecture based on the PCI Express technology. The Advanced Switching specification establishes a management infrastructure which maintains the fabric operation. The topology discovery process is triggered after fabric initialization and every time a topological change is detected. The information gathered by this process is used to build a set of paths between fabric endpoints. This work analyzes the performance of several possible implementations for this management task.

- by R. Casado
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- Routing, Topology, Network Management, Topology Discovery

For sensor networks deployed to collect and transmit events into a sink node, sink anonymity is a critical security property. Traditional encryption and authentication are not effective in terms of preserving the sink's location because attackers can determine its location through traffic analysis. In this paper, we propose an easy to implement Concealing of the Sink Location (CSL) technique, which is based on the use of fake message injection. CSL is able to prevent attackers from acquiring valuable information on the sink's location through the traffic analysis attack. Simulation results demonstrate clearly that CSL protocol can hide effectively the sink's location. Although using fake messages consumes additional energy, the network's lifetime is not impacted, as will be shown.

- by Dimitrios Makrakis
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- Privacy, Wireless Sensor Networks, Topology, Cryptography

- by G. Junyent
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- Automatic Control, Network Management, Control Systems, Topology Discovery
- by Muhammad Azizur Rahman
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- Topology Discovery, Network Design, Simulation Tool, Computer

An important requirement in the IP-based control of TDM optical transport networks is to utilize the built-in protection capabilities of SONET unidirectional path switched rings (UPSRs) and automate UPSR protected path setup in mixed mesh-ring networks. This requires modifications to existing IP signaling and routing protocol and new processing rules at the network nodes. In this paper, we leverage IP

- by Vishal Sharma
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- Signal Processing, Routing, Automatic Control, Routing protocols

This paper describes the development of a formalism to represent Network Topology Information that provides hierarchical views of the network elements distribution, usable with advantage by management applications. It reviews some topology discovery tools and emphasizes the lack of a common methodology to represent the network cabling and organize the agent distribution information. The formalism, consisting on a descriptive language and on an object-oriented topology base, is described and some application areas, where this information can be used, are pointed. Finally, it presents a Management API, as part of the overall architecture, that helps to show the usability of the Topology Information Base.

- by José Luis Oliveira
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- Distributed Computing, Topology Discovery, Network Topology, Object Oriented

Several recently emerged Internet services make use of application-level or overlay networks. Examples of such services include overlay multicast, structured peer-to-peer lookup services, and peer-to-peer file sharing. Many of these services could benefit from a network distance prediction mechanism that estimates inter-host latencies. In this paper, we present PCoord, a distributed network coordinate system for overlay topology discovery and distance prediction. PCoord assigns coordinates to hosts on the Internet so that the Euclidean distances between hosts' coordinates accurately predict their network latencies. Most of the existing network coordinate systems rely on a fixed set of landmark nodes for coordinate computation. PCoord, in contrast, is a fully decentralized system that allows participating hosts in an overlay network to collaboratively construct an accurate geometric model of the overlay topology using a small number of peer-to-peer measurements. Under the PCoord framework, we present three different peer sampling and coordinate mapping schemes: RandPCoord, ClusterPCoord, and ActivePCoord. Through extensive simulations using both real network measurements and simulated topologies, we show that the geometric model constructed by PCoord predicts pair-wise host distances accurately and efficiently.

- by Li-wei Lehman
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- Topology Discovery, Geometric model, File Sharing, Peer to Peer