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One of the most important research fields of network sciences is the robustness of networks. A recently answered important question was the following: Which network topologies are more resistant to random malfunctions and/or direct attacks? Nevertheless, until now, “which system topology can be maintained and how to manage maintenance more efficiently and effectively” have been open questions. However, these questions are the keys both to designing large-scale systems and to scheduling maintenance tasks. This paper proposes a new means to analyze the maintainability of a large system by combining two kinds of networks, i.e., the reliability diagram of the system (1) and the network of scheduled maintenance tasks (2). This paper shows how to assign maintenance task(s) to a system component to increase the reliability of the system. With the proposed method, the maintainability of large-scale systems can be analyzed. [ABSTRACT FROM AUTHOR]

Protocol Oblivious Forwarding (POF) aims at providing a standard southbound interface for sustainable Software Defined Networking (SDN) evolvement. It overcomes the limitations of popular OpenFlow protocols (an existing widely-adopted southbound interface), through the enhancement of SDN forwarding plane. This paper pioneers the design and implementation of a Kernel-space POF Virtual Switch (K_POFVS) on Linux platform. K_POFVS can improve the packet processing speed, through fast packet forwarding and the capability of adding/deleting/modifying protocol fields in kernel space. In addition, it is able to enhance flow table matching speed, by separating the mask table (consisting of flow entry masks used to figure out the matching field) and the flow table under a caching mechanism. Furthermore, K_POFVS can achieve efficient communication between the kernel space and the user space, via extending the netlink communication between them. Experimental results show that K_POFVS can provide much better performance than existing user-space POF virtual switches, in terms of packet forwarding delay, packet processing delay and packet transmission rate. [ABSTRACT FROM AUTHOR]

Congestion control is an extremely important area within wireless sensor networks (WSN), where traffic becomes greater than the aggregated or individual capacity of the underlying channels. Therefore, special considerations are required to develop more sophisticated techniques to avoid, detect, and resolve congestion. The constrained resources of the WSN must be considered while devising such techniques to achieve the maximum throughput. Various approaches have been introduced in the past few years that include routing protocols aided with congestion detection and control mechanism, and dedicated congestion control protocols. In the former schemes, the congestion avoidance is performed by the sink node that causes topology reset and bulk traffic drop. As a consequence, the latter mentioned congestion control protocols addressing the congestion avoidance, detection, and resolution were introduced at the node level. In this paper, we explore mechanisms for controlling congestion in the WSNs and present a comparative study. The congestion control schemes are categorized as centralized with partial congestion control and distributed with dedicated congestion control. [ABSTRACT FROM AUTHOR]

The work, presented in this article, aims at performing scheduling analysis of Time Division Multiple Access (TDMA) based communication systems. Products called software radio protocols, developed at Thales Communications & Security, are used as case-studies. Such systems are real-time embedded systems. They are implemented by tasks that are statically allocated on multiple processors. A task may have an execution time, a deadline and a release time that depend on TDMA configuration. The tasks also have dependencies through precedence and shared resources. TDMA-based software radio protocols have architecture characteristics that are not handled by scheduling analysis methods of the literature. A consequence is that existing methods give either optimistic or pessimistic analysis results. We propose a task model called Dependent General Multiframe (DGMF) to capture the specificities of such a system for scheduling analysis. The DGMF task model describes, in particular, the different jobs of a task, and task dependencies. To analyze DGMF tasks, we propose their transformation to real-time transactions and we also propose a new schedulability test for such transactions. The general analysis method is implemented in a tool that can be used by software engineers and architects. Experimental results show that our propositions give less pessimistic schedulability results, compared to fundamental methods. The results are less pessimistic for both randomly generated systems and real case-studies from Thales. These results are important for engineering work, in order to limit the over-dimensioning of resources. Through tooling, we also automated the analysis. These are advantages for engineers in the more and more competitive market of software radios. [ABSTRACT FROM AUTHOR]

Abstract: Full duplex wireless communication is one of the enabling technologies of the fifth generation (5G) mobile telecommunication networks. It boosts up the bandwidth by enabling simultaneous data transmission and reception on a single channel. In this paper, we design a suitable medium access control (MAC) protocol for 5G networks to realize the benefit of full duplex communication. We also develop an analytical model to evaluate the performance of our proposed MAC protocol. [ABSTRACT FROM AUTHOR]

Edge-independent spanning trees (EISTs) have important applications in networks such as reliable communication protocols, one-to-all broadcasting, and secure message distribution, thus their designs in several classes of networks have been widely investigated. The n -dimensional augmented cube ( A Q n ) is an important variant of the n -dimensional hypercube. It is ( 2 n − 1 )-regular, ( 2 n − 1 )-connected ( n ≠ 3 ), vertex-symmetric and has diameter of ⌈ n / 2 ⌉ . In this paper, by proposing an O ( N log ⁡ N ) algorithm that constructs 2 n − 1 EISTs in A Q n , where N is the number of nodes in A Q n , we solve the EISTs problem for this class of graphs. Since A Q n is ( 2 n − 1 )-regular, the result is optimal with respect to the number of EISTs constructed. [ABSTRACT FROM AUTHOR]

Many of the communication protocols developed for the resource constrained devices are rarely subjected to protocol verification. Design flaws like deadlocks, livelocks, non-progressive cycles etc. may come into view during the realization and can cause catastrophic effects in safety-critical applications. Formal specification of the protocol represented as a model helps to describe and analyse the conformability of the implementation to its specification and subsequently reveal design flaws, if any in the system. The formal model is subject to verification by inserting correctness and safety properties of the protocol and validating logical correctness using a model checking tool. All model checkers suffer from state explosion problem due to enormous states of the model being created. The key contribution of the present work is the introduction of a method to develop a compact verification model which is amenable to full state space search by abstracting the key elements of a protocol. Moreover, many protocol verification works presented in the existing literature consider only a single layer of a communication protocol. To correctly model the overall behaviour of a protocol, interactions between the layers have to be incorporated. The proposed method has been proven useful by considering verification of an application protocol, CoAP for constrained devices by abstracting out the aspects of the underlying routing protocol RPL. Reliable message exchanges among various entities are modeled and its safety and correctness properties were analysed and verified. The results obtained show that the model performs the full state space search by considering all possible routing paths and are free from design flaws. The method described has been implemented by building a validation model in PROMELA and the model is verified by using SPIN model checker. The methodology used in this paper can be used to verify any application layer protocol for constrained devices in IoT scenario that run on top of routing layer. [ABSTRACT FROM AUTHOR]

Several studies in the past have revealed that network end user devices are left powered up 24/7 even when idle just for the sake of maintaining Internet connectivity. Network devices normally support low power states but are kept inactive due to their inability to maintain network connectivity. The Network Connectivity Proxy (NCP) has recently been proposed as an effective mechanism to impersonate network connectivity on behalf of high power devices and enable them to sleep when idle without losing network presence. The NCP can efficiently proxy basic networking protocol, however, proxying of Internet based applications have no absolute solution due to dynamic and non-predictable nature of the packets they are sending and receiving periodically. This paper proposes an approach for proxying Internet based applications and presents the basic software architectures and capabilities. Further, this paper also practically evaluates the proposed framework and analyzes expected energy savings achievable under- different realistic conditions. [ABSTRACT FROM AUTHOR]

Ubiquitous devices used in the day-to-day activities of the modern world, increases the usage of internet via WiFi network. The development of technology and the raise in internet access leads to wireless spectrum scarcity in the ISM band. The deployment of Cognitive radio (CR) in the WiFi network with dynamic channel switching can overcome the spectrum shortage. This integration brings the challenge of jamming in CR network and WiFi network together devastates the availability of the spectrum in Cognitive WiFi (CWF) network. A novel LU-MAC protocol is proposed for CWF network that dynamically operate in both licensed and unlicensed band to increase the spectrum availability with jamming resistant. The LU-MAC protocol have been designed with control frame specification, Data Channel Switching (DCS) process and coordination modules, control channel switching process, synchronization module to obtain the benefit of cognitive radio technology in WiFi network. It is deployed using Intrusion Detection System (IDS), Random Frequency Hopping Pattern (RFHP) generation algorithm and Statistic-based Reactive Channel Switching (SRCS) algorithms to counter the jamming attack. The performance of the LU-MAC protocol is evaluated using the Glomosim simulator. It shows the efficient communication in CWF network with the existence of the jamming attacker. [ABSTRACT FROM AUTHOR]

In this paper, we present an Efficient COngestion DEtection (ECODE) protocol that aims at evaluating the traffic characteristics of each road segment (i.e., the road section connecting between any two successive intersections). Moreover, ECODE efficiently and reliably detects road segments with high traffic congestion in any urban grid-layout area. The traffic situation and the congestion level of each road segment changes from time to time. Proactive, reactive, and hybrid iterative execution schemes have been proposed to execute ECODE repeatedly and to thus obtain a more real-time traffic evaluation of each road segment. These iterative execution schemes aim also at investigating the effects of several data dissemination mechanisms that are usually used to control the congestion over the communication network. ECODE is discussed and its performance is reported on and compared to previous protocols in this field; an extensive set of scenarios and experiments have been used which are in turn implemented by NS-2. From the experimental results, ECODE achieves a 30% more accurate evaluation of traffic characteristics compared to previous protocols in this field. Moreover, it consumes on average 60% of the bandwidth that was consumed by the previous protocols. Considering the iterative execution schemes of ECODE, the proactive scheme consumes 50% more bandwidth than the reactive scheme. However, the accuracy of the traffic evaluation per road segment using the reactive scheme is lower than the accuracy of the proactive scheme used for short intervals. The hybrid scheme lies between the proactive and the reactive schemes in terms of the bandwidth consumption and the accuracy of congestion level evaluation. Finally, we have used ECODE to evaluate the traffic congestion level and to investigate the traffic distribution over some main streets in the downtown area of Ottawa; this has been set up as a practical example of the application of ECODE. [ABSTRACT FROM AUTHOR]

In this paper, the classical debate on suitability of proactive versus reactive routing approaches is revisited, however in the context of their application in Low-Power Lossy Networks (LLNs) as opposed to pure Mobile Ad Hoc Networks (MANETs). We argue that LLNs differ from traditional ad hoc networks not only due to node capacity, but also in the nature of traffic generation and routing requirements. This study aims at a fair comparison between two protocols proposed at the IETF, namely RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) - the proactive candidate, and LOADng (LLN On-demand Ad-hoc Distance vector routing protocol - next generation) - the reactive candidate, making use of real traffic scenarios and topology deployments of varied size, as well as random topologies in the particular case of metrics relating to scalability. Several metrics of interest are investigated, including metrics that have not been paid much attention in the existing MANET literature. In the course of this investigation, we also uncovered non-optimal protocol behavior for the case of large networks and proposed new mechanisms that are shown to improve control plane congestion, as a result improving network lifetime for large scale LLNs. We also derive bounds on control overhead for the two protocols, which indicate that RPL incurs an overhead that is lower than O(N2) and reduces to Θ(Nlog(N)) for a balanced tree structure, whereas LOADng has a total control overhead of Θ(N2), irrespective of topology. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2009.02.003 Byline: G.D. Pallas, G.I. Papadimitriou, A.S. Pomportsis Keywords: Broadcast local area networks; Time division multiple access; Medium Access Control protocol Abstract: Hybrid TDMA (Time Division Multiple Access) with heuristic traffic shaping (HyTDMA/HTS) is a new collisionless MAC protocol for efficiently managing the traffic of a heavy loaded broadcast LAN. The protocol employs techniques that enable it to perform better than both fixed assignment protocols like TDMA as well as dynamic bandwidth allocation protocols like LTDMA. HyTDMA/HTS can smoothly operate in diverse traffic environments of very high loads and bursty traffic, and it can still maintain maximum shared medium utilization while maintaining low packet delay times. Built into the protocol is also a simple yet effective heuristic mechanism that regulates the traffic of hosts flooding the network with an excessive number of packets larger than the average. Author Affiliation: Aristotle University, Department of Informatics, 54124 Thessaloniki, Greece Article History: Received 17 April 2008; Revised 9 February 2009; Accepted 10 February 2009 Article Note: (miscellaneous) Responsible Editor: A. Popescu

The location-based routing protocol has been chosen as one of the efficient routing approaches in vehicular ad hoc networks in terms of low overhead and high scalability. Its critical advantage lies in performing a pathless routing such that a node having a packet forwards it to its neighbor node that provides the shortest physical distance to destination and this process continues until the packet reaches destination. The problem lies in that the link stability of the neighbors varies largely depending on the mobility of vehicles and the environmental factors that incur shadowing and fading effects. In this paper, we propose a new link quality prediction metric associated with location based protocols to improve the selection of next hop, that consider both the link quality assessment based on the transmission success rate and the link quality assessment based on the prediction of the future locations of vehicles. Simulation results are presented to demonstrate the efficiency of the proposed metric. [ABSTRACT FROM AUTHOR]

Highlights: [•] We propose a novel clustering protocol ECDS, which considers coverage and energy efficiency simultaneously. [•] We propose two new metrics CI p and CI a and for coverage performance. [•] ECDC has better performance compared with some other clustering protocols. [ABSTRACT FROM AUTHOR]

Abstract: Vehicular ad hoc networks (VANETs) have emerged to leverage the power of modern communication technologies, applied to both vehicles and infrastructure. Allowing drivers to report traffic accidents and violations through the VANET may lead to substantial improvements in road safety. However, being able to do so anonymously in order to avoid personal and professional repercussions will undoubtedly translate into user acceptance. The main goal of this work is to propose a new collaborative protocol for enforcing anonymity in multi-hop VANETs, closely inspired by the well-known Crowds protocol. In a nutshell, our anonymous-reporting protocol depends on a forwarding probability that determines whether the next forwarding step in message routing is random, for better anonymity, or in accordance with the routing protocol on which our approach builds, for better quality of service (QoS). Different from Crowds, our protocol is specifically conceived for multi-hop lossy wireless networks. Simulations for residential and downtown areas support and quantify the usefulness of our collaborative strategy for better anonymity, when users are willing to pay an eminently reasonable price in QoS. [Copyright &y& Elsevier]

Abstract: Improving road safety and optimizing road traffic relies on both Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications. The successful deployment of vehicular communication depends on the two contentious factors, security and privacy. Though several researches have been conducted on the issuance of pseudonyms to deal with these issues, the traditional PKI based schemes used for the generation of these pseudonyms produce an enormous signing and verification costs. In order to address this problem, we propose a novel scheme in which the RSUs in a VANET use a one-way hash chain scheme to generate a series of public/private key pairs and to distribute them along with an n bit hash code and a proof cipher to the vehicles in its range. Since the RSU will provide a synchronized clock to all vehicles, anytime a vehicle can verify another vehicle by combining the vehicle’s public key and its n bit hash code, which should prove the same cryptographic hash function of the receiving vehicle. Through this proposed Hash-chain based Authentication Protocol (HAP), the certificate costs of messages are immensely reduced. Moreover, if an attacker tries to compromise a node’s public key it will be infeasible for him/her to achieve the desired task, as the vehicle frequently changes its public/private keys in a random fashion and hence guarantees a secured vehicle communication. We analyzed the proposed protocol extensively to validate its better performance when compared to its counterparts. [Copyright &y& Elsevier]

Abstract: The design of the readout and data acquisition system of the future KM3NeT neutrino telescope employs 10Gbps photonic technologies for data transmission to shore. The photonic architecture can handle standard transmission protocols. The generic scheme is based on DWDM technology using lasers on shore and optical modulators in each of the 12,800 Digital Optical Modules arranged on several hundred vertical detection units anchored to the seabed. Each module will house 31 photomultipliers together with auxiliary instrumentation and readout electronics. A 100km electro-optical fibre cable will connect the optical modules to the store. The readout system will guarantee an individual optical connection between each optical module and the shore. A small-scale prototype of a detection unit with four optical modules is in a realization phase and will allow for in situ testing of the data transmission network. We will present results of laboratory tests of the photonics-oriented transmission layer of the network that have been realized for the prototype detection unit. [Copyright &y& Elsevier]

Abstract: This paper presents the design and performance evaluation of a stable pairwise time synchronization protocol (abbreviated SPS) for capillary machine-to-machine (M2M) networks that provides underlying platform independence and operational stability, even under harsh conditions. SPS achieves the first criterion using a novel technique whereby the M2M device captures incoming or outgoing moments of timing messages. The second criterion is achieved by adaptively adjusting the resynchronization interval. Extensive simulations are conducted to demonstrate the validity and effectiveness of SPS. [Copyright &y& Elsevier]

Abstract: Paxos is probably the most popular state machine replication protocol. Two optimizations that can greatly improve its performance are batching and pipelining. However, tuning these two optimizations to achieve high-throughput can be challenging, as their effectiveness depends on many parameters like the network latency and bandwidth, the speed of the nodes, and the properties of the application. We address this question by presenting an analytical model of the performance of Paxos, and showing how it can be used to determine configuration values for the batching and pipelining optimizations that result in high-throughput. We then validate the model, by presenting the results of experiments where we investigate the interaction of these two optimizations both in LAN and WAN environments, and comparing these results with the prediction from the model. The results confirm the accuracy of the model, with the predicted values being usually very close to the ones that provide the highest performance in the experiments. Furthermore, both the model and the experiments give useful insights into the relative effectiveness of batching and pipelining. They show that although batching by itself provides the largest gains in all scenarios, in most cases combining it with pipelining provides a very significant additional increase in throughput, with this being true not only on high-latency WAN but also in many LAN scenarios. [Copyright &y& Elsevier]

Abstract: The Address Resolution Protocol (ARP) is used to resolve the MAC address of a host given its IP address. ARP is stateless, as there is no authentication when exchanging a MAC address between hosts. Hacking methods using ARP spoofing are being continuously abused in various ways, and there have been many prior studies of the prevention of such attacks. However, prevention requires the modification of the basic network protocol or expensive additional equipment, so it is hard to apply these methods to the current network. In this paper, we examine the limits of prior research into ARP spoofing prevention. In addition, we suggest a defense mechanism that does not require changes to the network protocol or expensive equipment. Our system automatically renews the reliable MAC address information to the ARP table as a static type to protect users from ARP spoofing. [Copyright &y& Elsevier]

Abstract: Negotiation is a general mechanism for reaching an agreement that involves multiple individuals. In multi-agent sys- tems, automatic negotiation is one of the main ongoing research issues. Over the last two decades, many attempts have been made to handle naturally distributed agreement problems via automatic negotiation. These naturally distributed problems are easy to understand for their simplicity, but are hard to handle automatically. In order to reach an agreement using automatic negotiation, there is a need for a structured negotiation protocol. In this paper, we propose an agent negotiation protocol for meeting scheduling, one of the prominent naturally distributed problem. This paper assumes that there is a scheduling agent and it has the knowledge about user preferences, meeting participants’profile, holds a reasoning mechanism to evaluate a meeting invitation, and capable of selecting negotiation strategies automatically. The proposed negotiation protocol assists the meeting scheduling agent to handle bilateral and multilateral negotia- tion scenarios. We demonstrate a number of meeting scheduling scenarios to show how the protocol assists automatic negotiation process and its effectiveness during the scheduling activities. [Copyright &y& Elsevier]

Abstract: Many spectrum usage measurement reports have shown that the fixed-frequency allocation mechanism causes unbalanced resource occupancy. Most of the current devices are constrained, preventing their performance from being optimized. This paper proposes the MHC-MAC protocol. It has asynchronous assembly line mode cognitive MAC aimed at improving the HC-MAC protocol performance with low throughput and channel utilization rate. From the sensing time, task number, licensed channel number and data packet length aspects, mathematical model and program simulation results are presented to demonstrate that MHC-MAC is better than HC-MAC in spectrum utilization and network capacity. [Copyright &y& Elsevier]

Abstract: Distributed monitoring is challenging yet essential in order to address scalability issues observed in the context of large-scale plan execution. A formal framework can be very helpful in analyzing and reasoning about plan spec- ification, execution, and monitoring. In this paper, we elaborate on a distributed monitoring calculus framework that allows specifying and executing plans for multi-agent systems in a distributed environment. The framework allows taking into account a highly dynamic and uncertain environment that can be a contributor to the changing conditions possibly disrupting and causing the plan to fail. Furthermore, the calculus provides sound foundations for designing and evaluating monitoring algorithms and protocols. In order to achieve effective monitoring, we propose an automata- based approach, inspired by runtime security verification research initiatives. The proposed automata allow enforcing monitoring properties while the given plan is executed at the agent's side. [Copyright &y& Elsevier]

Abstract: The bandwidth is one of the most precious resources in Mobile Ad Hoc Networks (MANETs); their network protocols should therefore be able to achieve an increase in efficiency of bandwidth utilisation. TCP, which implements flow control to regulate the network traffic, plays a significant role in shaping the workload of the network. However, spurious TCP retransmissions can increase the link utilisation, consequently limiting the amount of spare bandwidth available as extensively reported in the literature. This problem is exacerbated by the presence of high priority traffic and traffic differentiation introduced in IEEE 802.11e. In this paper, we focus on the optimisation of TCP for resource efficiency, by limiting the number of contention-induced retransmissions. Using a cross-layer technique, TCP can be notified of the medium contention state and adjusts its retransmission timer accordingly. Our simulation results demonstrate the effectiveness of our proposal in various scenarios. A 15% gain in resource utilisation is obtained, fewer packets are retransmitted thus reducing the overall power consumption and TCP goodput is improved. [Copyright &y& Elsevier]

Abstract: Directory-based cache coherency is commonly accepted as the design of choice to provide high performance and scalability in coherency maintenance for many-core CMPs. However, the on-chip area overhead required to encode sharer sets may compromise their success as core count increases. In this work, we propose the Express COherence NOtification (ECONO) protocol, a simple and efficient Dir0B cache coherence protocol that does not require sharer sets encoding while approaching performance of a conventional directory-based protocol. To accomplish that, ECONO relies on express coherence notifications which are broadcast atomically over a dedicated lightweight on-chip network leveraging state-of-the-art technology. Detailed full-system simulation using a representative set of benchmarks corroborates our statement. [Copyright &y& Elsevier]

Abstract: The Eclipse Parallel Tools Platform (PTP) is an open source Integrated Development Environment (IDE) aiding the development of Supercomputer applications. The PTP parallel debugger is used by a growing community of developers in scientific and engineering fields. This paper proposes a method of improving the communication infrastructure of the PTP debugger by taking advantage of a Scalable Parallel Debugging Library (SPDL). Unlike the present communication framework of PTP, the Scalable Debug Manager (SDM), SPDL provides a pluggable architecture that allows developers to select a communication protocol suitable for a targeted supercomputer. It currently supports a number of scalable protocols, including MRNet and SCI. The advanced features provided by these communication trees, like programmable filters and configurable topologies, allow developers to create more flexible solutions of efficient reduction and aggregation operations for parallel debugging. In particular, they allow parallel debuggers to handle the large amounts of back-end messages in peta-scale environments with better efficiency. The architecture of the PTP debugger is extended to support SPDL. The extended architecture combines the advantages of the PTP debugger at the front-end and SPDL at the back-end. It improves the scalability and performance of the PTP debugger. Consequently, it provides a flexible option of utilizing the PTP debugger with pluggable communication protocols to address the debugging challenges in peta-scale environments. [Copyright &y& Elsevier]

Abstract: Moon and Lee recently designed an authentication protocol for an ad hoc network using an identifier [Mathematical and Computer Modelling]. The main contribution of this method is that it can effectively reduce the authentication overheads compared with related works. Unfortunately, we have found that the authentication protocol has suffered from the man-in-the-middle attack. [Copyright &y& Elsevier]

Abstract: A password based authenticated key exchange protocol is of practical usefulness in the protection of sharing of urban rail train sensor monitoring data. However, many password-based protocols in the literature were not secure. Recently, Huang presented a simple and efficient three-party password-based authenticated key exchange protocol. However, Yoon et al. found it had some security weaknesses. In this paper, we further show it has another critical security weakness, which opens door to a partition attack (offline dictionary attack). Thereafter we propose an enhanced protocol that can defeat the attacks described (including Yoon et al.’s attacks) and yet is reasonably efficient. Furthermore, our protocol can resist against the stolen-verifier attacks and achieve the provable security. [Copyright &y& Elsevier]

Abstract: Several IP mobility support protocols have been standardized. Each solution provides a specific functionality and/or requires operations of particular nodes. The current trend is towards the co-existence of these solutions, though the impact of doing so has not been yet fully understood. This article reviews key standards for providing IP mobility support, the functionality achieved by combining them, and the performance cost of each combination in terms of protocol overhead and handover latency. We show that combining different mobility mechanisms has a non-negligible cost. Finally we identify a strategy for combining mobility protocols and properties that facilitate this combination. [Copyright &y& Elsevier]

Abstract: A power-aware route maintenance protocol for Mobile Ad Hoc Networks (MANETs) is introduced. Termed Dynamic Path Switching (DPS), the new protocol puts an overloaded node to sleep before a route link breaks because that node runs out of energy, and brings other suitable nodes into play instead. When the battery charge of a node reaches a stated level, the node can advance a request to change to a sleep state for a while. The request is honoured unless survival of some path rests on the forwarding activity of that very node. All nodes are assumed to be collaborative. The DPS protocol is fully backward compatible, as it can be implemented within existing routing protocols such as Dynamic Source Routing (DSR). The new protocol has been extensively simulated with the established network simulator NS2. The findings indicate a much improved power awareness of the updated routing protocol with respect to the unadorned one. Power saving is particularly effective during long-lived sessions. [Copyright &y& Elsevier]

This study provides field research evidence on the efficiency of a “free-selection” peer review assignment protocol as compared to the typically implemented “assigned-pair” protocol. The study employed 54 sophomore students who were randomly assigned into three groups: Assigned-Pair (AP) (the teacher assigns student works for review to student pairs), Free-Selection (FS) (students are allowed to freely explore and select peer work for review), and No Review (NR) (control group). AP and FS student groups studied and reviewed peer work in the domain of Computer Networking, supported by a web-based environment designed to facilitate the two peer review protocols. Our results indicate that students following the Free Selection protocol demonstrate (a) better domain learning outcomes, and (b) better reviewer skills, compared to the AP condition. Overall, the study analyzes the benefits and shortcomings of the FS vs AP review assignment protocol, providing evidence that the FS condition can be multiply beneficial to students who engage in peer review activities. [Copyright &y& Elsevier]

Abstract: This paper presents a new wireless sensor network energy-efficient MAC protocol, ES-MAC protocol, and shows the results of simulation experiments. During the transmission the nodes do not send ACK packages while use a small amount of new information packets, so they can reduce unnecessary energy loss and wasted time. The theoretical analysis and simulation results show that ES-MAC protocol reduces energy consumption while reducing network latency and improving network throughput. [Copyright &y& Elsevier]

Abstract: Distributed logic programming languages, which allow both facts and programs to be distributed among different nodes in a network, have been recently proposed and used to declaratively program a wide-range of distributed systems, such as network protocols and multi-agent systems. However, the distributed nature of the underlying systems poses serious challenges to developing efficient and correct algorithms for evaluating these programs. This paper proposes an efficient asynchronous algorithm to compute incrementally the changes to the states in response to insertions and deletions of base facts. Our algorithm is formally proven to be correct in the presence of message reordering in the system. To our knowledge, this is the first formal proof of correctness for such an algorithm. [Copyright &y& Elsevier]

Abstract: Although many studies have focused on testing computer networks under realistic traffic loads by means of genetic algorithms (GAs), little attention has been paid to optimising the parameters of the GAs in this problem. The objective of this work is to design and validate a system that, given some constraints on traffic bandwidth, generates the worst-case traffic for a given computer network and finds the traffic configuration (critical background traffic) that minimises throughput in that computer network. The proposed system is based on a meta-GA, which is combined with an adaptation strategy that finds the optimum values for the GA control parameters and adjusts them to improve the GA''s performance. To validate the approach, different comparisons are performed with the goal of assessing the acceptable optimisation power of the proposed system. Moreover, a statistical analysis was conducted to ascertain whether differences between the proposed system and other algorithms are significant. The results demonstrate the effectiveness of the system and prove that, when the background traffic is driven by a GA that uses the parameters obtained from the system, the computer network''s performance is much lower than when the traffic is generated by Poisson statistical processes or by other algorithms. This system has identified the worst traffic pattern for the protocol under analysis. [Copyright &y& Elsevier]

Abstract: An innovative energy-efficient network design algorithm and a tool to lower the network power consumption are proposed. The goal is an energy efficient network that carries its rated communication load while meeting the QoS requirements by using the minimum set of nodes and links. QoS metrics include hop limit, bandwidth limit reliability and stability. The proposed algorithm addresses the set-covered problem. To discover the optimum network configuration efficiently, we propose a network configuration generation algorithm that utilizes DAPDNA-2, a parallel data flow type reconfigurable processer. The processor automatically produces the node/link set in n-digit binary form where links are modeled as “1” for power on and “0” for power off; it also confirms that the QoS requirements are satisfied. Evaluation results show that DAPDNA-2 is 2-orders faster than the conventional sequential method running on a Pentium-4 processor. Prototype Gigabit Layer-2 switches having remote link power on/off and traffic monitoring functions are developed. Using these switches, we successfully demonstrate an energy efficient IP/Ethernet network. The evaluation results show that network power savings of up to 30% can be realized under the NFSNET topology model. The proposed algorithm and power efficient network architecture can be applied to realize the future green network. [Copyright &y& Elsevier]

Abstract: In this paper, an optimal routing strategy is proposed to enhance the traffic capacity of complex networks. In order to avoid nodes overloading, the new algorithm is derived on the basis of generalized betweenness centrality which gives an estimate of traffic handled by the node for a route set. Since the nodes with large betweenness centrality are more susceptible to traffic congestion, the traffic can be improved, as our strategy, by redistributing traffic load from nodes with large betweenness centrality to nodes with small betweenness centrality in the proceeding of computing collective routing table. Particularly, depending on a parameter that controls the optimization scale, the new routing can not only enlarge traffic capacity of networks more, but also enhance traffic efficiency with smaller average path length. Comparing results of previous routing strategies, it is shown that the present improved routing performs more effectively. [Copyright &y& Elsevier]

Abstract: Ad-hoc networks suffer from the problem of hidden nodes (terminals), which leads to severe degradation of network throughput. This survey gives a comprehensive overview of Medium Access Control (MAC) protocols which directly or indirectly address this problem. The presented protocols are grouped in several categories and are described in the order of their publication date. To give the reader a deep understanding of the progress made in the area of alleviating the hidden node problem a brief summary of the key ideas as well as a detailed comparison of different protocols are presented. Open research directions are also discussed to serve as a starting point for future protocol design and evaluation. [Copyright &y& Elsevier]

Abstract: The Internet Key Exchange (IKE) protocol is most widely used as a secure key exchange protocol to exchange key materials and negotiate security associations between two security gateways for any secure communications over Internet. However, the original IKE is too flexible, complex and weak to denial-of-service (DoS) attack; several enhanced IKE version have been proposed to replace the original one. In this paper, an elliptic curve cryptography (ECC) based and certificate less IKE protocol is proposed. It eliminates the use of certificates for authentication, replaces the RSA based Diffie-Hellman (DH) key exchange by Elliptic Curve Diffie-Hellman (ECDH) key exchange, and instead of cookies, hash value of initiator''s public key, identity and IP address is used to prevent DoS attack. One advantage of the proposed scheme is that it provides same level of security as RSA with less key size, as well as it generates an ECC based common secret key, used for symmetric encryption, which requires less processing time, less computation cost and less storage space than the time required in the public key encryption-based techniques. [Copyright &y& Elsevier]

Abstract: The KNX standard for home and building automation has been recently updated by the definition of KNXnet/IP system. It allows integration of different KNX networks through IP using the KNXnet/IP Router. Due to the limited transmission speeds of the KNX, the KNXnet/IP Router may represent a bottleneck. The aim of the paper is to analyse the effect of congestion of KNXnet/IP Router on the information flow exchanged between different KNX networks; furthermore, the analysis will focus on the impact of the two policies available inside the KNXnet/IP Router to forward telegrams coming from IP towards the relevant KNX network. [Copyright &y& Elsevier]

Abstract: An energy efficient, scalable and collision free MAC protocol, DTFMM, is presented in this paper, which combines frequency and time division principles for medium sharing. It is based on clustered network topology, and the protocol employs a distributed local coordinate algorithm for assigning channels among clusters to enable simultaneous non-interfering data collection. Intra-cluster transmissions are scheduled by cluster head (CH) based on time slot. CHs aggregate the gathered data and forward it over inter-CH paths to the base-station based on minimum spanning tree routing. Distinct channels are adopted by the independent branches of the inter-CH routing tree. Data transmission on a branch is further scheduled in depth-first ordering. DTFMM allows nodes to stay in sleeping mode for the longest duration and thus it minimizes energy consumption. Simulation demonstrated superiority of DTFMM in terms of convergent rate, throughput and delay performance when compared with well-known protocol MMSN. [Copyright &y& Elsevier]

Abstract: Recently, the technologies for child care and safety have been developing rapidly, together with the various IT convergence services. In particular, several mobile operators (e.g., SKT, KTF, and LGT) in Korea and Gangnam province in Seoul provide their own child-care services. However, some problems such as incorrect location information, privacy violation, and difficulty of an end-user to control the child-care service still exist. In this paper, we derive the security requirements of a child-care and safety service and establish a conceptual model satisfying the requirements. Based on the system model, we propose a privacy-preserving location supporting protocol for a child-care and safety service using wireless sensor networks. While addressing the above problems, our protocol can be operated over various networks (e.g., Wi-Fi and UWB) providing an RSSI (received signal strength indication) without any modification. Through performance and security analysis of our protocol, we show that our protocol is efficient and secure. More precisely, our protocol reduces the computation and communication overhead of the existing infrastructures to support better scalability. [Copyright &y& Elsevier]

Abstract: The network management protocol SNMP has its flaws,but it has not solved by itself. So other secure protocol must be borrowed to deal with the flaws of SNMP. It is a good method that the Secure Shell Protocol(SSH) can resolved the flaws of SNMP. In this paper the Secure Shell Security Model is constructed based on the SSH and analyzed its performance, which is good to the network security management. [Copyright &y& Elsevier]

Abstract: Toward problems with a single node of failure, overhead, weakly-scalable and the intricacy and inefficiency of the key agreement and refreshment in the traditional key agreement management with MANET, here, this paper propose a solution which can enhance the scalability, decrease single failure, contribute to the balance of load and reduce the price of key revocation and refresh by mean of trust relationship mechanism based on the node mobility and secret key pre-distribution. [Copyright &y& Elsevier]

Abstract: In this paper, we explore the problem of multi-channel assignment and switching based routing for Mobile Internet. A new routing schema to solve this problem is presented, which is called Multi-channel Assignment and Switching based Routing, namely MASR. In this method, node-based channel assignment is considered, and we introduce the concept of dependent router, with which a hierarchical and fragmented routing protocol is proposed. Extensive simulations are conducted and the results have shown that compared with MCRP and MCP-LB, our schema has better performance. It can improve the total throughput of the network greatly. [Copyright &y& Elsevier]

Abstract: In the networking research and development field, one recurring problem faced is the duplication of effort to write first simulation and then implementation code. We posit an alternative development process that takes advantage of the built in network emulation features of Network Simulator 3 (ns-3) and allows developers to share most code between simulation and implementation of a protocol. Tests show that ns-3 can handle a data plane processing large packets, but has difficulties with small packets. When using ns-3 for implementing the control plane of a protocol, we found that ns-3 can even outperform a dedicated implementation. [Copyright &y& Elsevier]

Abstract: In this paper, a lawyer office’s network and internet traffic will be examined for determining the characteristics of users and network traffic load. In order to do that, some modifications on the lawyers office is made. Firstly, the switch which was previously used, replaced with a smart switch which can mirror traffic to a special port. Later, the office adsl modem is replaced with a modified Linux distribution. These linux device is used as a adsl modem/router for the network. This device also logged every incomming packet including the payload from it’s both interfaces. After a months full run, the data gathered is collected and analized. [Copyright &y& Elsevier]

Abstract: Emerging applications of wireless sensor networks (WSN) requiring wide-band event signal communication such as multimedia surveillance sensor networks impose additional challenges including high communication bandwidth requirement and energy cost. Besides their partially or fully dependency on feedback messages from sink node, the existing protocols designed for WSN do not address the communication of wide-band event signals. Furthermore, the feedback messages may not reach in time to provide reliable communication of event information and save scarce network resources. Therefore, an autonomous communication protocol is imperative in order to provide wide-band event signal communication without any feedback from the sink. In nature, biological systems have self-organization capability, i.e., homeostasis, as they autonomously maintain a relatively stable equilibrium state for operation of vital functions. Hence, this natural phenomenon clearly gives promising inspirations in order to develop autonomous and efficient communication models and protocols for WSN domain. In this paper, the homeostasis-inspired autonomous communication (HAC) protocol is introduced for wireless audio sensor networks (WASN). Using the spectral properties of the wide-band event signal, i.e., audio signal, HAC enables WASN to maintain a relatively stable state in which sensor nodes reliably and energy-efficiently communicate the event signal to the sink node. Furthermore, with its self-organization capability, HAC does not rely on any feedback message from the sink node. Performance evaluations reveal that HAC successfully communicates wide-band event signal with minimum energy expenditure. [Copyright &y& Elsevier]

Abstract: We extend here the Population Protocol (PP) model of Angluin et al. (2004, 2006) in order to model more powerful networks of resource-limited agents that are possibly mobile. The main feature of our extended model, called the Mediated Population Protocol (MPP) model, is to allow the edges of the interaction graph to have states that belong to a constant-size set. We then allow the protocol rules for pairwise interactions to modify the corresponding edge state. The descriptions of our protocols preserve both the uniformity and anonymity properties of PPs, that is, they do not depend on the size of the population and do not use unique identifiers. We focus on the computational power of the MPP model on complete interaction graphs and initially identical edges. We provide the following exact characterization of the class of stably computable predicates: a predicate is in  iff it is symmetric and is in . [Copyright &y& Elsevier]

Abstract: We study the throughput and delay scaling laws of the mobile cognitive network. There are primary users and secondary users in the primary network and the secondary network, respectively. They are distributed uniformly and independently on the surface of a unit torus, moving according to the random way-point mobility model (RWMM). The primary users have priority to access the spectrum, and do not alter their protocol in the presence of the secondary network. The secondary users opportunistically use the licensed spectrum when it remains unused. Under the improved 2-hop relay policy, we derive the constant throughput of per primary source–destination (S–D) pair when the radius of the preservation region . The expected delay scales as , where is the average speed of the primary nodes. Moreover, if the secondary network is denser than the primary network, i.e., with , the constant throughput of per secondary S–D pair and the expected delay of can be derived surprisingly when the radius of the avoidance region and , where is the average speed of the secondary nodes. [Copyright &y& Elsevier]