Controlling unresponsive connections in an active network architecture

Critical node discovery plays a vital role in assessing the vulnerability of a computer network to malicious attacks and failures and provides a useful tool with which one can greatly improve network security and reliability. In this paper, we propose a new metric to characterize the criticality of a node in an arbitrary computer network which we refer to as the Combined Banzhaf & Diversity Index (CBDI). The metric utilizes a diversity index which is based on the variability of a node׳s attributes relative to its neighbours and the Banzhaf power index which characterizes the degree of participation of a node in forming shortest paths. The Banzhaf power index is inspired from the theory of voting games in game theory. The proposed metric is evaluated using analysis and simulations. The criticality of nodes in a network is assessed based on the degradation in network performance achieved when these nodes are removed. We use several performance metrics to evaluate network performance including the algebraic connectivity which is a spectral metric characterizing the connectivity robustness of the network. Extensive simulations in a number of network topologies indicate that the proposed CBDI index chooses more critical nodes which, when removed, degrade network performance to a greater extent than if critical nodes based on other criticality metrics were removed.

We study the degradation in network performance caused by the selfish behavior of noncooperative network users. We consider a directed network in which each edge possesses a latency function describing the common latency incurred by all traffic on the edge as a function of the edge congestion. Given a rate of traffic between each pair of nodes in the network, we aspire toward an assignment of traffic to paths in which the sum of all travel times (the total latency) is minimized; however, in many settings network users are free to route their traffic in a selfish manner, without regard to the total latency. We therefore assume that each network user routes its traffic on the minimum-latency path available to it, given the network congestion caused by the other users. In general such a selfishly motivated assignment of traffic to paths (a Nash equilibrium) will not minimize the total latency; hence, selfish behavior carries the cost of decreased network performance. We quantify this degradation in network performance via the price of anarchy, defined as the worst possible ratio between the total latency of a Nash equilibrium and of a minimum-latency routing of the traffic.In this paper, we show that the underlying network topology plays no role in the determination of the price of anarchy. Specifically, we show that under weak hypotheses on the class of allowable edge latency functions, the worst-case ratio between the total latency of a Nash equilibrium and of a minimum-latency routing for any multicommodity flow network is achieved by a single-commodity instance on a set of parallel links. In the special case where the class of allowable latency functions includes all of the constant functions, we prove that a network with only two parallel links suffices to achieve the worst-possible ratio. Informally, these results imply that the inefficiency inherent in a flow at Nash equilibrium stems from the inability of selfish users to discern which of two competing routes is superior and not from the topological complexity arising from the diverse intersections of many paths belonging to different commoditie.Our proof techniques also give powerful methods for computing the price of anarchy with respect to an arbitrary class of latency functions. We apply these methods to function classes that have been well studied in the literature (such as degree-bounded polynomials and functions of the form $\ell(x) = (u—x)—1} that are used to model edges with capacity u), thereby achieving the first tight analyses of the price of anarchy for significant classes of latency functions outside the class of linear functions.

Quantifying the resilience of community structures in networks

본 논문에서는 디바이스의 이동으로 인한 WiMedia 네트워크의 성능 저하를 개선하기 위한 릴레이 통신 기법을 제안하였다. WiMedia 프로토콜은 고속의 전송속도를 지원하기 때문에, 선박 네트워크(Ship Area Network)등과 같은 환경에서 고속의 전송률을 요구하는 실시간 멀티미디어 서비스 제공과 같은 응용분야에 적합하다. 하지만, 디바이스의 이동은 네트워크 토폴로지와 디바이스간 링크 상태의 급격한 변화를 야기하며, 네트워크의 성능 저하의 원인이 되기도 한다. 본 논문에서는 기존의 WiMedia 프로토콜에서는 채널의 링크 상태 변화를 적절하게 대처하지 못하여 발생하는 네트워크 성능저하를 해결하는 릴레이 통신 기법을 제안하였다. In this paper, a relay communication scheme for enhancing the WiMedia network performance by device's mobility is proposed. WiMedia protocol is suitable for the application that supports the real-time multimedia service in Ship Area Network since it supports high speed data transfer. However, the device's mobility is caused the dramatic change of link state and network topology, and is occurred the degradation of network performance. Therefore, a relay communication scheme for WiMedia network is proposed in this paper. The proposed technique can intelligently treat the change of link state, and solve the degradation of network performance.

This paper presents the details of the policy-based security and resource management architecture for Application Level Active Network (alan) servers.alan is an active network architecture which enables deployment of user-customised processes (proxylets), which enhance the existing services or introduce new services to the end-user, on the select group of servers in anip network. The issues of security and resource management in this scenario are of crucial importance so as to efficiently facilitate and control the resource consumption of user-specified processes on the active servers, as well as to protect the server platforms from unauthorised proxylet deployment or malevolent behaviour. The architecture allowing efficient resource and security control is presented in this paper, including detaileduml diagrams capturing the management functionality, as well as a set of concrete management policies for thealan scenario. The examplexml policies are also given, and the deployment of this architecture in real-life trials is described. This development forms a part of a larger management architecture foralan-enabled networks developed in the context of theist projectandroid (Active Network DistRibuted Open Infrastructure Development).

Existing active network architectures depend on using statically typed languages for protection and performance. Unfortunately, this limits some of the more dynamic features of an active network. In this paper, we present PANTS (Python Active Node Transfer System)-a dynamically extensible active network architecture. We describe a new architecture for an active node which does not depend on language-based security but provides the flexibility to perform dynamic changes to the node and to the capsules. An implementation conforming to this architecture is described and compared with existing active network architectures.

In the immediate aftermath of devastating earthquakes such as in the 6 February 2023 Kahramanmaraş sequence in southcentral Türkiye, key stakeholders and the public demand timely and accurate earthquake information. Especially for large events, finite-fault models provide important insights into the rupture process and enable interpretation of the observed ground shaking, which can improve situational awareness and facilitate rapid assessment of future hazards. Using strong-motion waveforms recorded during the Kahramanmaraş sequence, we simulate a real-time playback and calculate how a finite-source model computed with the Finite-fault rupture Detector (FinDer) algorithm would evolve for the Mw 7.8 Pazarcık, Mw 7.6 Elbistan, and Mw 6.4 Yayladağı earthquakes. Using template matching FinDer compares observed and predicted ground-motion acceleration amplitudes to determine the orientation and spatial extent of fault rupture. We test both generic crustal and fault-specific templates from ground-motion models and rupture geometries of the east Anatolian and Çardak–Sürgü faults. In the second step, we estimate the seismic slip along the source models from the backprojection of the seismic displacement amplitudes. The algorithms achieve excellent performance for all three earthquakes, and the final source models and slip profiles available within tens of seconds of the rupture nucleation match well with models computed days to weeks after the events occurred. The temporal evolution of the source models for the Pazarcık and Elbistan earthquakes suggests that FinDer can provide insight into the rupture kinematics of large earthquakes. Cascading instrument failures as well as power and data telemetry interruptions during the Pazarcık earthquake led to an early termination of signals at a significant number of near-source stations. We show that FinDer is robust enough to cope with this type of degradation in network performance that can occur in large earthquakes, in general.

Fundamental to the Network Administrator's consideration of risk on a network are issues of security namely; confidentiality, integrity and availability of information assets. The ability to effectively and efficiently manage the network and make room for growth without degradation in network performance are equally considerable concerns. The segmentation of a significantly large Local Area Network with a possible annual growth rate of over 10% is undoubtedly the surest way to effectively manage the network, ensure security of information assets and make it scalable. This paper seeks to assess the Pentecost University College(PUC) campus network at Sowutuom to determine how optimally segmented it is and the most practical option of using Virtual LANs to optimize the segmentation for effective and efficient security, management and scalability. Based on the information gathered and analysis carried out on the network, a proposal is advanced to enhance the segmentation of the campus network with an eye towards the future growth.

Broadcasting has many important uses and several mobile ad hoc networks (MANETs) protocols assume the availability of an underlying broadcast service. Applications, which make use of broadcasting, include LAN emulation, paging a particular node. However, broadcasting induces what is known as the "broadcast storm problem" which causes severe degradation in network performance, due to excessive redundant retransmission, collision, and contention. Although probabilistic flooding has been one of the earliest suggested approaches to broadcasting. There has not been so far any attempt to analyse its performance behaviour in MANETs. This paper investigates using extensive ns-2 simulations the effects of a number of important parameters in a MANET, including node speed, pause time and, traffic load, on the performance of probabilistic flooding. The results reveal that while these parameters have a critical impact on the reachability achieved by probabilistic flooding, they have relatively a lower effect on the number of saved rebroadcast packets

As the importance of the Internet increases, developing technologies for data transmission at higher bit rates became as important as challenging. Optical Transport Networks (OTN), based on Wavelength Division Multiplexing (WDM), emerged to meet this need. ITU has standardized OTN, including its management functions. Network elements in OTN store performance monitoring information as time series of performance events, which could be explored to enable more efficient preventive maintenance and better resource provisioning. With the use of time series forecasting models, faults could even be avoided, along with Service Level Agreement breaches. In this work, we propose the use of time series forecasting in performance monitoring of OTN, investigating how three forecasting methods behave in scenarios of stability and degradation in network performance and how the number of monitoring intervals affects their accuracy. In accordance with results we state recommendations for application of tested time series forecasting methods in managing OTN.

We consider the problem of routing traffic to optimize the performance of a congested network. We are given a network, a rate of traffic between each pair of nodes, and a latency function for each edge specifying the time needed to traverse the edge given its congestion; the objective is to route traffic such that the sum of all travel times---the total latency---is minimized.In many settings, it may be expensive or impossible to regulate network traffic so as to implement an optimal assignment of routes. In the absence of regulation by some central authority, we assume that each network user routes its traffic on the minimum-latency path available to it, given the network congestion caused by the other users. In general such a "selfishly motivated" assignment of traffic to paths will not minimize the total latency; hence, this lack of regulation carries the cost of decreased network performance.In this article, we quantify the degradation in network performance due to unregulated traffic. We prove that if the latency of each edge is a linear function of its congestion, then the total latency of the routes chosen by selfish network users is at most 4/3 times the minimum possible total latency (subject to the condition that all traffic must be routed). We also consider the more general setting in which edge latency functions are assumed only to be continuous and nondecreasing in the edge congestion. Here, the total latency of the routes chosen by unregulated selfish network users may be arbitrarily larger than the minimum possible total latency; however, we prove that it is no more than the total latency incurred by optimally routingtwiceas much traffic.

In this paper we propose a platform that optimizes the available end-to-end throughput in real time through overlay networks. With the knowledge the network topology and conditions, it strives to achieve the optimal end-to-end throughput by exploring the last-mile diversity. It allows the flexible and responsive per-end-user selection of the edge node for the overlay networks, and thus can fast recover from network failures and performance degradation. We present our design of the end-to-end throughput optimization system with detailed discussion of each component including dynamic routing engine, performance monitor and information exchange. Our experimental results from a real-world deployment show that compared to the performance-oblivious routing, it not only brings up to 5 times throughput gains in the presence of 0.05% loss, but also improves 20% throughput when facing delay increase in the original path.

Background: With the advancement of Industry 4.0, the automation of industrial processes has shifted from wired communication technologies to wireless networks, enabling greater flexibility, efficiency, and scalability. Technologies such as LoRaWAN and NB-IoT have been widely adopted due to their low energy consumption and long-range communication capabilities, which are essential for industrial applications. However, the increasing density of connected devices has introduced new challenges, particularly related to electromagnetic interference (EMI), which can degrade network performance, cause packet loss, and delay communication. EMI, caused by various sources such as electronic devices and natural phenomena, is a critical issue in industrial environments. EMI simulations and analyses allow for network parameter adjustments and the implementation of mitigation techniques, ensuring robust communications. This study's primary objective is to test the radiated electromagnetic immunity of the LoRa protocol, assessing its ability to operate in environments subject to electromagnetic interference. The research emphasizes the importance of understanding EMI impacts to preserve data accuracy, improve communication performance, and ensure regulatory compliance, fostering a safe, reliable, and efficient industrial environment. Materials and Methods: The study evaluates the radiated electromagnetic immunity of Heltec LoRa ESP32 V2 boards, essential for IoT applications, in compliance with the IEC 61000-4-3 standard, which establishes methods for testing immunity to high-frequency electromagnetic fields. The boards were tested in an anechoic chamber to analyze the impact of radiated fields on LoRa communication. During the tests, conducted at frequencies from 80 MHz to 6 GHz and with a field intensity of 10 V/m, a transmitting board continuously sent LoRa packets while the receiving board recorded RSSI values and packet reception rates. The results demonstrated the sensitivity of the LoRa protocol to electromagnetic interference, evidenced by RSSI variations and packet losses under certain conditions. The tests highlighted the importance of robust configurations to maintain data integrity and device functionality in challenging industrial environments. The study provides valuable insights for improving electromagnetic compatibility in Industry 4.0 and IoT applications, meeting the criteria established by the IEC 61000-4-3 standard. Results: The study identified critical communication disruptions in the LoRa system at specific frequencies (305 MHz and 730 MHz) under radiated electromagnetic fields with a power of 1.5 dBm, characterized by packet loss and performance degradation. At 3 dBm, total communication failure occurred, attributed to internal resonances in the RF components and insufficient shielding or filtering of the modules. The interference likely overlapped with harmonics of the LoRa signal, reducing its ability to distinguish useful signals from noise. These findings highlight the system's vulnerability to specific EMI conditions, emphasizing the need for improved filtering, shielding, and protocol adjustments to enhance robustness in industrial environments. Conclusion: The study finds LoRa unstable at 305 MHz and 705 MHz with 1.5 dBm, causing packet loss and potential communication failure, highlighting the need for mitigation in high-interference environments.

A mobile agent-based active network architecture for intelligent network control

Active networks allow their users to inject customized programs into the nodes of the network. An extreme case, in which we are most interested, replaces packets with "capsules" - program fragments that are executed at each network router/switch they traverse.Active architectures permit a massive increase in the sophistication of the computation that is performed within the network. They will enable new applications, especially those based on application-specific multicast, information fusion, and other services that leverage network-based computation and storage. Furthermore, they will accelerate the pace of innovation by decoupling network services from the underlying hardware and allowing new services to be loaded into the infrastructure on demand.In this paper, we describe our vision of an active network architecture, outline our approach to its design, and survey the technologies that can be brought to bear on its implementation. We propose that the research community mount a joint effort to develop and deploy a wide area ActiveNet.