Comparative Performance Analysis of Selected Routing Algorithms by Load Variation of 2-Dimensional Mesh Topology Based Network-On-Chip

Network-on-Chip (NoC) has been proposed as a viable solution to the communication challenges on System-on-Chips (SoCs). As the communication paradigm of SoC, NoCs performance depends mainly on the type of routing algorithm chosen. In this paper different categories of routing algorithms were compared. These include XY routing, OE turn model adaptive routing, DyAD routing and Age-Aware adaptive routing. By varying the load at different Packet Injection Rate (PIR) under random traffic pattern, comparison was conducted using a 4 × 4 mesh topology. The Noxim simulator, a cycle accurate systemC based simulator was employed. The packets were modeled as a Poisson distribution; first-in-first-out (FIFO) input buffer channel with a depth of five (5) flits and a flit size of 32 bits; and a packet size of 3 flits respectively. The simulation time was 10,000 cycles. The findings showed that the XY routing algorithm performed better when the PIR is low. In a similar vein, the DyAD routing and Age-aware algorithms performed better when the load i.e. PIR is high.

A Node Confident based IDS to Avoid Packet Drop Attacks for Wireless Sensor Network

Because of the great characteristics of Wireless Sensor Networks like easier to use and less cost of deployment, they have attracted the researchers to conduct the investigations and received the importance in various civilian and military applications. A number of security attacks have been involved due to the lack of centralized management in these networks. The packet drop attack is one of the attacks and it has a compromised node which drops the malicious packets. In WSNs, different techniques have been implemented to identify the packet drop attack but none of them provides the feasibility to stop or isolate their occurrence in the future. In recent times, the reputation systems provide the way to identify the trustworthy nodes for data forwarding. But the lack of data classification in the reputation systems affects the false positive rate. In this paper, a novel CONFIDENT SCORE based BAYESIAN FILTER NODE MONITORING AGENT (CFS-BFNMA) mechanism is introduced to identify & avoid the packet drop nodes and also to monitor the node behaviours to improve the false positive rate. The final CFS of a node is estimated based on the node past and threshold CFS values. The node monitoring agents (BFNMA) constantly monitors the forwarding behaviour of the nodes and assigns CFS based on the successful forwards. The NMA saves the copy of the data packets in their buffers before forwarding to the neighbour nodes to compare them. Also, this BFNMA analyses the traffic pattern of every round of transmission to improve the false positive rate. By comparing with other conventional security algorithms, the proposed mechanism has been improved the network security & false positive rate drastically based on the simulation results.

THE SAIMAA CANAL IN THE INLAND WATER CARGO TRANSPORTATION SYSTEM

The article deals with the research of the Saimaa Canal significance in the Finnish transport sphere. The analysis of the canal characteristics and features, which are es-sential for shipping, as well as the Saimaa Canal traffic volumes, their commodity struc-ture, the Saimaa Canal ship calls and cargo traffic pattern of change are given. The cer-tain prospects for increasing the traffic on the Saimaa Lakes and especially on the ca-nal is considered.

From “Onion Not Found” to Guard Discovery

We present a novel web-based attack that identifies a Tor user’s guard in a matter of seconds. Our attack is low-cost, fast, and stealthy. It requires only a moderate amount of resources and can be deployed by website owners, third-party script providers, and malicious exits—if the website traffic is unencrypted. The attack works by injecting resources from non-existing onion service addresses into a webpage. Upon visiting the attack webpage with Tor Browser, the victim’s Tor client creates many circuits to look up the non-existing addresses. This allows middle relays controlled by the adversary to detect the distinctive traffic pattern of the “404 Not Found” lookups and identify the victim’s guard. We evaluate our attack with extensive simulations and live Tor network measurements, taking a range of victim machine, network, and geolocation configurations into account. We find that an adversary running a small number of HSDirs and providing 5 % of Tor’s relay bandwidth needs 12.06 seconds to identify the guards of 50 % of the victims, while it takes 22.01 seconds to discover 90 % of the victims’ guards. Finally, we evaluate a set of countermeasures against our attack including a defense that we develop based on a token bucket and the recently proposed Vanguards-lite defense in Tor.

Developing the Fringe Routing Protocol

<p>An ISP style network often has a particular traffic pattern not typically seen in other networks and which is a direct result of the ISP’s purpose, to connect internal clients with a high speed external link. Such a network is likely to consist of a backbone with the clients on one ‘side’ and one or more external links on the other. Most traffic on the network moves between an internal client and the external world via the backbone. But what about traffic between two clients of the ISP? Typical routing protocols will find the ‘best’ path between the two gateway routers at the edge of the client stub networks. As these routers connect the stubs to the ISP core, this route should be entirely within the ISP network. Ideally, from the ISP point of view, this traffic will go up to the backbone and down again but it is possible that it may find another route along a redundant backup path. Don Stokes of Knossos Networks has developed a protocol to sit on the client fringes of this ISP style of network. It is based on the distance vector algorithm and is intended to be subordinate to the existing interior gateway protocol running on the ISPs backbone. It manipulates the route cost calculation so that paths towards the backbone become very cheap and paths away from the backbone become expensive. This forces traffic in the preferred direction unless the backup path ‘shortcut’ is very attractive or the backbone link has disappeared. It is the analysis and development of the fringe routing protocol that forms the content of this ME thesis.</p>

Developing the Fringe Routing Protocol

<p>An ISP style network often has a particular traffic pattern not typically seen in other networks and which is a direct result of the ISP’s purpose, to connect internal clients with a high speed external link. Such a network is likely to consist of a backbone with the clients on one ‘side’ and one or more external links on the other. Most traffic on the network moves between an internal client and the external world via the backbone. But what about traffic between two clients of the ISP? Typical routing protocols will find the ‘best’ path between the two gateway routers at the edge of the client stub networks. As these routers connect the stubs to the ISP core, this route should be entirely within the ISP network. Ideally, from the ISP point of view, this traffic will go up to the backbone and down again but it is possible that it may find another route along a redundant backup path. Don Stokes of Knossos Networks has developed a protocol to sit on the client fringes of this ISP style of network. It is based on the distance vector algorithm and is intended to be subordinate to the existing interior gateway protocol running on the ISPs backbone. It manipulates the route cost calculation so that paths towards the backbone become very cheap and paths away from the backbone become expensive. This forces traffic in the preferred direction unless the backup path ‘shortcut’ is very attractive or the backbone link has disappeared. It is the analysis and development of the fringe routing protocol that forms the content of this ME thesis.</p>

Correlated Bayesian Model of Aircraft Encounters in the Terminal Area Given a Straight Takeoff or Landing

The incorporation of unmanned aircraft terminal operations into the scope of Detect and Avoid systems necessitates analysis of the safety performance of those systems&mdash;principally, an assessment of how well those systems prevent loss of well clear from and collision with other aircraft. This type of analysis has typically been conducted by Monte Carlo simulation with synthetic, statistically representative encounters between aircraft drawn from an appropriate encounter model. While existing encounter models include terminal airspace classes, none explicitly represents the structure expected while engaged in terminal operations, e.g., aircraft in a traffic pattern. The work described herein is an initial model of such operations, scoped at this time specifically for assessment of unmanned aircraft landings and encounters with other aircraft either landing or taking off. The model shares the Bayesian network foundation of other MIT Lincoln Laboratory encounter models but tailors those networks to address structured terminal operations, i.e., correlations between trajectories and the airfield and each other. This initial model release is intended to elicit feedback from the standards-writing community.

TDTS: Three-Dimensional Traffic Scheduling in Optical Fronthaul Networks with Conv-LSTM

Given the more intensive deployments of emerging Internet of Things applications with beyond-fifth-generation communication, the access network becomes bandwidth-hungry to support more kinds of services, requiring higher resource utilization of the optical fronthaul network. To enhance resource utilization, this study novelly proposed a three-dimensional traffic scheduling (TDTS) scheme in the optical fronthaul network. Specifically, large and mixed traffic data with multiple different requirements were firstly divided according to three-dimensions parameters of traffic requests, i.e., arriving time, transmission tolerance delay, and bandwidth requirements, forming eight types of traffic model. Then, historical traffic data with division results were put into convolutional-long short-term memory (Conv-LSTM) strategy for traffic prediction, obtaining a clear traffic pattern. Next, the traffic processing order was supported by a priority evaluation factor that was measured by traffic status of the link and network characteristics comprehensively. Finally, following the priority, the proposed TDTS scheme assigned the resource to traffic requests according to their results of traffic division, prediction, and processing order with the shortest path routing and first-fit spectrum allocation policies. Simulation results demonstrated that the proposed TDTS scheme, on the premise of accurate traffic prediction, could outperform conventional resource-allocation schemes in terms of blocking probability and resource utilization.

A Large-scale Analysis of Hundreds of In-memory Key-value Cache Clusters at Twitter

Modern web services use in-memory caching extensively to increase throughput and reduce latency. There have been several workload analyses of production systems that have fueled research in improving the effectiveness of in-memory caching systems. However, the coverage is still sparse considering the wide spectrum of industrial cache use cases. In this work, we significantly further the understanding of real-world cache workloads by collecting production traces from 153 in-memory cache clusters at Twitter, sifting through over 80 TB of data, and sometimes interpreting the workloads in the context of the business logic behind them. We perform a comprehensive analysis to characterize cache workloads based on traffic pattern, time-to-live (TTL), popularity distribution, and size distribution. A fine-grained view of different workloads uncover the diversity of use cases: many are far more write-heavy or more skewed than previously shown and some display unique temporal patterns. We also observe that TTL is an important and sometimes defining parameter of cache working sets. Our simulations show that ideal replacement strategy in production caches can be surprising, for example, FIFO works the best for a large number of workloads.

Modelling of safe traffic schema for marine area

Статья посвящена проблеме обеспечения безопасности движения судов на морских акваториях. В условиях насыщенного трафика навигационная безопасность может быть обеспечена только при соблюдении судами определённой схемы движения. В работе ставится задача планирования системы маршрутов (схемы движения) судов через акватории с интенсивным трафиком. Эта схема зависит от географии акватории и особенностей трафика. Выбор того или иного варианта схемы обусловлен необходимостью обеспечения максимальной безопасности движения и практическими соображениями. В основу метода решения задачи положено моделирование движения судов по множеству возможных траекторий и оценка метрики, описывающей степень опасности движения. В качестве такой метрики предлагается частота опасных сближений судов, отмечается возможность использования и других метрик. В работе показано, что модельное представление задачи на основе взвешенного графа не даёт возможности её решения без привлечения специализированных вычислительных ресурсов. Альтернативным подходом является конструирование схем движения экспертным способом из типичных структурных элементов (примитивов). Имитационное моделирование задачи изолированно в рамках отдельного примитива вполне возможно на доступных вычислительных и программных платформах общего назначения. В работе рассмотрено четыре таких примитива, оценено среднее время между опасными сближениями судов для каждого из них. Приведён пример использования полученных результатов моделирования для планирования безопасных схем движения судов. This work is devoted to the problem of ensuring the safety of vessel traffic at marine areas. Navigation safety in conditions of heavy traffic can be ensured only if the vessels comply with a certain traffic pattern. The paper highlights the problem of planning a system of routes (traffic patterns) of vessels through water areas with heavy traffic. This schema depends on the geography of the water area and the characteristics of traffic. The necessity to ensure the maximum safety of vessel traffic and practical considerations determine the choice of a specific variant for a traffic scheme. Modeling the vessels motion along a set of possible trajectories and evaluating the metric describing the degree of movement danger is the basis of the method for solving the problem. The frequency of dangerous approaches of vessels is proposed as a metric for assessing the danger of traffic, and the possibility of using other metrics is noted. The work demonstrates that the model representation of the problem based on a weighted graph does not allow its solution without the involvement of specialized computing resources. An alternative approach is motion construction of schemes in an expert way from typical structural elements (primitives). Simulation modeling of a problem becomes possible on available general-purpose computing and software platforms if it is isolated within a separate primitive. The paper considers four such primitives and estimates the average time between dangerous approaches of vessels for each of them. An example of using the obtained modeling results for planning safe ship traffic patterns is given.