In an IP over WDM network architecture, IP traffic is carried over a virtual topology (VT), composed of optical transparent channels called lightpaths. We propose an energy-efficient dynamic VT adaptation method with sleep mode, which allows changing only one lightpath connectivity at a time by dynamically monitoring the IP packet traffic load on each lightpath. In order to assure the connectivity of future traffic increase a high-load threshold is used. When the packet traffic load on a specific lightpath becomes higher than a threshold, a new lightpath is added to the virtual topology. However this congestion avoidance policy increases the power consumption by activating transponders in the network. Therefore at the same time lightly loaded lightpaths are eliminated in the virtual topology by using a low-load threshold. Energy-efficient virtual topology adaptation is achieved by traffic offloading considering both lightly loaded and heavily loaded links in the network. In this regard, high-and low-load threshold values need to be carefully determined in order to both gain power and ensure load balancing with keeping the stability of virtual connectivity at a reasonable level.We have analysed the power consumption of the network during 48-hours for different values of low-and high-load thresholds together with the impact of different threshold values on the stability of the virtual topology. We have shown that there is a trade-off between number of changes in the virtual topology and the energy-efficiency. Experimental results demonstrate that a good compromise can be achieved by adjusting the high-and low-load thresholds carefully. Keywords: Energy-efficiency, IP over WDM networks, optical WDM networks, virtual topology reconfiguration, dynamic traffic.
INTRODUCTIONInternet has become a significant part of our daily life leading to a rapid increase in traffic rates. Power consumption per user is continuously increasing although power consumption per bit is decreasing with the evolution of power efficient devices in telecommunication networks. In order to meet the requirements of this increasing traffic demands, today's optical wavelength division multiplexing (WDM) networks as a backbone transmission system, is designed to be over-dimensioned, with extra switching capacity and excess number of deployed links, taking into account the peak rates and future growth of the traffic, resulting in waste of energy.In an IP over WDM network architecture, IP traffic is carried over a virtual topology (VT), composed of optical transparent channels called lightpaths. In transparent optical networks, lightpaths are the most power consuming elements due to the electro-optical operations during the add/drop. Generally, the intensity of traffic on lightpaths follows a daily traffic profile, decreases during the early hours of the morning, starts to increase again after 9 am, and peaks during the daytime. In different time zones, the peak traffic intensities occur at different times, relative to a global clock reference...
Ransomware uses encryption methods to make data inaccessible to legitimate users. To date a wide range of ransomware families have been developed and deployed, causing immense damage to governments, corporations, and private users. As these cyberthreats multiply, researchers have proposed a range of ransomware detection and classification schemes. Most of these methods use advanced machine learning techniques to process and analyze real-world ransomware binaries and action sequences. Hence this paper presents a survey of this critical space and classifies existing solutions into several categories, i.e., including network-based, host-based, forensic characterization, and authorship attribution. Key facilities and tools for ransomware analysis are also presented along with open challenges.
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