БАЛАНСУВАННЯ САМОПОДІБНОГО ТРАФІКУ В МЕРЕЖНИХ СИСТЕМАХ ВИЯВЛЕННЯ ВТОРГНЕНЬ

The problem of load balancing in intrusion detection systems is considered in this paper. The analysis of existing problems of load balancing and modern methods of their solution are carried out. Types of intrusion detection systems and their description are given. A description of the intrusion detection system, its location, and the functioning of its elements in the computer system are provided. Comparative analysis of load balancing methods based on packet inspection and service time calculation is performed. An analysis of the causes of load imbalance in the intrusion detection system elements and the effects of load imbalance is also presented. A model of a network intrusion detection system based on packet signature analysis is presented. This paper describes the multifractal properties of traffic. Based on the analysis of intrusion detection systems, multifractal traffic properties and load balancing problem, the method of balancing is proposed, which is based on the funcsioning of the intrusion detection system elements and analysis of multifractal properties of incoming traffic. The proposed method takes into account the time of deep packet inspection required to compare a packet with signatures, which is calculated based on the calculation of the information flow multifractality degree. Load balancing rules are generated by the estimated average time of deep packet inspection and traffic multifractal parameters. This paper presents the simulation results of the proposed load balancing method compared to the standard method. It is shown that the load balancing method proposed in this paper provides for a uniform load distribution at the intrusion detection system elements. This allows for high speed and accuracy of intrusion detection with high-quality multifractal load balancing.У даній роботі розглянута проблема балансування навантаження в системах виявлення вторгнень. Проведено аналіз існуючих проблем балансування навантаження та сучасних методів їх вирішення. Наведено типи систем виявлення вторгнень та їх опис. Представлено опис мережної системи виявлення вторгнень, розташування та функціонування її елементів в комп’ютерній системі. Проведено порівняльний аналіз методів балансування навантаження на основі прийому пакетів та на основі розрахунку часу обслуговування. Також представлено аналіз причин дисбалансу навантаження в елементах системи виявлення вторгнень та наслідків дисбалансу навантаження. Представлено модель мережної системи виявлення вторгнень на основі сигнатурного аналізу пакетів. В даній роботі зазначено мультифрактальні властивості трафіку. На основі проведеного аналізу систем виявлення вторгнень, мультифрактальних властивостей трафіку та проблеми балансування навантаження запропоновано метод балансування, який заснований на роботі елементів системи виявлення вторгнень і аналізі мультифрактальних властивостей вхідного трафіку. Запропонований метод враховує час глибокої перевірки пакетів, що необхідний для порівняння пакета з сигнатурами, який обчислюється на основі розрахунку ступеня мультифрактальності інформаційного потоку. Правила балансування навантаження генеруються за допомогою оціненого середнього часу глибокої перевірки пакетів і параметрів мультифрактальності вхідного навантаження. В даній роботі наведено результати імітаційного моделювання запропонованого методу балансування навантаження в порівнянні зі стандартним методом. Показано, що запропонований в даній роботі метод балансування навантаження забезпечує рівномірний розподіл навантаження на вузлах системи виявлення вторгнень. Це дозволяє забезпечити високу швидкість і точність визначення вторгнень при якісному балансуванні мультифрактального навантаження

Locational-based Coupling of Electricity Markets: Benefits from Coordinating Unit Commitment and Balancing Markets

We formulate a series of stochastic models for committing and dispatching electric generators subject to transmission limits. The models are used to estimate the benefits of electricity locational marginal pricing (LMP) that arise from better coordination of day-ahead commitment decisions and real-time balancing markets in adjacent power markets when there is significant uncertainty in demand and wind forecasts. The unit commitment models optimise schedules under either the full set of network constraints or a simplified net transfer capacity (NTC) constraint, considering the range of possible real-time wind and load scenarios. The NTC-constrained model represents the present approach for limiting day-ahead electricity trade in Europe. A subsequent redispatch model then creates feasible real-time schedules. Benefits of LMP arise from decreases in expected start-up and variable generation costs resulting from consistent consideration of the full set of network constraints both day-ahead and in real-time. Meanwhile, using LMP to coordinate adjacent balancing markets provides benefits because it allows intermarket flow schedules to be adjusted in real-time in response to changing conditions. These models are applied to a stylised four-node network, examining the effects of varying system characteristics on the magnitude of the locational-based unit commitment benefits and the benefits of intermarket balancing. Although previous www.eprg.group.cam.ac.uk EPRG WORKING PAPER studies have examined the benefits of LMP, these usually examine one specific system, often without a discussion of the sources of these benefits, and with simplifying assumptions about unit commitment. We conclude that both categories of benefits are situation dependent, such that small parameter changes can lead to large changes in expected benefits. Although both can amount to a significant percentage of operating costs, we find that the benefits of balancing market coordination are generally larger than the unit commitment benefits

Using Negotiation to Reduce Redundant Autonomous Mobile Program Movements

Distributed load managers exhibit thrashing where tasks are repeatedly moved between locations due to incomplete global load information. This paper shows that systems of Autonomous Mobile Programs (AMPs) exhibit the same behaviour, identifying two types of redundant movement and terming them greedy effects. AMPs are unusual in that, in place of some external load management system, each AMP periodically recalculates network and program parameters and may independently move to a better execution environment. Load management emerges from the behaviour of collections of AMPs. The paper explores the extent of greedy effects by simulation, and then proposes negotiating AMPs (NAMPs) to ameliorate the problem. We present the design of AMPs with a competitive negotiation scheme (cNAMPs), and compare their performance with AMPs by simulation

Improved natural balancing with modified phase shifted PWM for single-leg five-level flying-capacitor converters

Flying capacitor converters (FCCs), as most multilevel converter topologies, require a balancing mechanism of the capacitor voltages. FCCs have the valuable property of natural voltage balancing when a special modulation technique is used. The classic methods, like Phase-Shifted Pulse Width Modulation (PS-PWM), result in very slow balancing for some duty ratio ranges. Previous work showed that for a single-leg five-level FCC one time constant is infinite for a zero desired output voltage. In this paper, a modified PS-PWM scheme for a single-leg fivelevel FCC is presented which results in faster balancing over the total duty ratio range. The modified PS-PWM scheme is studied, resulting in an averaged voltage balancing model. This model is verified using simulations and experiments. The modified PS-PWM scheme solves the slow balancing problems of the normal PS-PWM method for odd-level FCCs, while maintaining the passive control property, and it provides a self-precharge capability

An Adaptive Soft Handover Scheme Using Fuzzy Load Balancing for WCDMA Systems

In cellular systems, user distribution variations can cause load imbalance between cells. Embedding a load balancing strategy within the handover scheme means that ensuing traffic congestion can be alleviated by dynamically reallocating load between neighbouring cells. An adaptive soft handover scheme for multimedia cellular communication systems is proposed in this paper, that considers both the cell load factors as well as the pilot channel signal-to-interference-and-noise-ratio (SINR) for soft handovers. By using fuzzy principles, the soft handover thresholds and time hysteresis are adapted dependent upon the loads of the neighbouring cells. Simulation results show that the new algorithm provides improved system performance in terms of a more evenly distributed load, lower blocking probabilities and higher throughput

EVEREST IST - 2002 - 00185 : D23 : final report

Deliverable públic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version