Web User-session Inference by Means of Clustering Techniques

This paper focuses on the definition and identification of “Web user-sessions”, aggregations of several TCP connections generated by the same source host. The identification of a user-session is non trivial. Traditional approaches rely on threshold based mechanisms. However, these techniques are very sensitive to the value chosen for the threshold, which may be difficult to set correctly. By applying clustering techniques, we define a novel methodology to identify Web user-sessions without requiring an a priori definition of threshold values. We define a clustering based approach, we discuss pros and cons of this approach, and we apply it to real traffic traces. The proposed methodology is applied to artificially generated traces to evaluate its benefits against traditional threshold based approaches. We also analyze the characteristics of user-sessions extracted by the clustering methodology from real traces and study their statistical properties. Web user-sessions tend to be Poisson, but correlation may arise during periods of network/hosts anomalous behavior

Load Balancing for Wireless network by using Min-Max algorithm

Network overload is one of the key challenges in wireless LANs. This goal is typically achieved when the load of access points is balanced. Recent studies on operational WLANs, shown that access point’s load is often uneven distribution i.e.it will be a crucial task to handle the load of overloaded server. To identify such overloaded server many kind of techniques like load balancing have been proposed already. These methods are commonly required proprietary software or hardware at the user side for controlling the user-access point association. In this proposed system we are presenting a new load balancing method by controlling the size of WLAN cells, which is conceptually similar to cell breathing in cellular networks. This method does not require any modification to the users neither the IEEE 802.11 standard. It only requires the ability of dynamically changing the transmission power of the AP beacon messages. We have develop a set of polynomial time algorithms which find the optimal beacon power settings which minimizes the load of the congested access point. We have also considered the problem of network-wide min-max load balancing. Simulation results show that the performance of the proposed method is comparable with or superior to the best existing association-based method

Resource-on-demand schemes in 802.11 WLANs with non-zero start-up times

Increasing the density of access points is one of the most effective mechanisms to cope with the growing traffic demand in wireless networks. To prevent energy wastage at low loads, a resource-on-demand (RoD) scheme is required to opportunistically (de)activate access points as network traffic varies. While previous publications have analytically modeled these schemes in the past, they have assumed that resources are immediately available when activated, an assumption that leads to inaccurate results and might result in inappropriate configurations of the RoD scheme. In this paper, we analyze a general RoD scenario with N access points and non-zero start-up times. We first present an exact analytical model that accurately predicts performance but has a high computational complexity, and then derive a simplified analysis that sacrifices some accuracy in exchange for a much lower computational cost. To illustrate the practicality of this model, we present the design of a simple configuration algorithm for RoD. Simulation results confirm the validity of the analyses, and the effectiveness of the configuration algorithm

NetGlance NMS - An integrated network monitoring system

Mestrado de dupla diplomação com a Kuban State Agrarian UniversityThis work is about IT infrastructure and, in particular, computer networks in KubSAU and IPB. Also, it is about a network monitoring system “NetGlance NMS” developed for KubSAU System Administration Department. Work objective is to optimize the information structure for KubSAU and IPB. During the work, following tasks were completed: Research the existing IPB information structure, Compare the information structure for KubSAU and IPB, Model the IPB computer network (topology, services), Research bottlenecks and potential pitfalls in the data-center and in the computer network of IPB, Research information security mechanisms in the computer network of IPB, Organize monitoring process for the computer network in KubSAU. The most important impact of the work is an increasing network productivity and user experience as a result of creation and deploy a monitoring software.O trabalho descrito no âmbito desta dissertação incide sobre a infraestrutura TI e, em particular, sobre as redes de computadores da KubSAU e do IPB. Além disso, descreve-se um sistema de gestão integrada de redes, designada “NetGlance NMS”, desenvolvido para o Departamento de Administração de Sistemas da KubSAU. O objetivo do trabalho é desenvolver uma ferramenta para otimizar a gestão da estrutura de comunicações das duas instituições. Durante o trabalho, as seguintes tarefas foram concluídas: levantamento da estrutura de comunicações do IPB, comparação da estrutura de comunicações entre a KubSAU e o IPB, modelação da rede de comunicações do IPB (topologia, serviços), estudo de possíveis estrangulamentos no datacenter e na rede de comunicações doIPB, estudo de mecanismos de segurança na rede de comunicações do IPB, organização do processo de monitorização da rede de comunicações da KubSAU. O contributo mais relevante deste trabalho é o desenvolvimento de uma aplicação de gestão integrada de redes, de forma a contribuir para o aumento da produtividade da rede e da experiência dos utilizadores

Improving the Performance of Wireless LANs

This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids

Protocol design and optimization for QoS provisioning in wireless mesh networks

Wireless Mesh Network (WMN) has been recognized as a promising step towards the goal of ubiquitous broadband wireless Internet access. By exploiting the state-of-the-art radio and multi-hop networking technologies, mesh nodes in WMN collaboratively form a stationary wireless communication backbone. Data between clients and the Internet is routed through a series of mesh nodes via one or multiple paths. Such a mesh structure enables WMN to provide clients high-speed Internet access services with a less expensive and easier-to-deployment wireless infrastructure comparing to the wired counterparts. Due to the unique characteristics of WMN, existing protocols and schemes designed for other wellstudied wireless networks, such as Wi-Fi and Mobile Ad-hoc Network (MANET), are not suitable for WMN and hence cannot be applied to WMN directly. Therefore, novel protocols specifically designed and optimized forWMNare highly desired to fully exploit the mesh architecture. The goal is to provide high-level Quality-of-Service (QoS) to WMN clients to enable a rich portfolio of wireless and mobile applications and scenarios. This dissertation investigates the following important issues related to QoS provisioning in WMN: high throughput routing between WMN clients and the Internet, fairness provisioning among WMN clients and network-level capacity optimization. We propose innovative solutions to address these issues and improve the performance, scalability and reliability of WMN. In addition, we develop CyMesh, a multi-radio multi-channel (MRMC) wireless mesh network testbed, to evaluate the capacity and performance of WMN in real world environments. Extensive simulation (using the QualNet simulator) and experimental (over the CyMesh testbed) results demonstrate the effectiveness of the designed protocols. In particular, we learn that the system capacity of WMN can be improved significantly by exploiting the MRMC network architecture and the antenna directionality of radios equipped on mesh nodes, and our proposed fulfillment based fairness is a reasonable notion for fair service provisioning among WMN clients. Moreover, we report the encountered problems, key observations and learned lessons during the design and deployment of CyMesh, which may serve as a valuable resource for future MRMC WMN implementations

Robust Mobile Data Transport: Modeling, Measurements, and Implementation

Advances in wireless technologies and the pervasive influence of multi-homed devices have significantly changed the way people use the Internet. These changes of user behavior and the evolution of multi-homing technologies have brought a huge impact to today\u27s network study and provided new opportunities to improve mobile data transport. In this thesis, we investigate challenges related to human mobility, with emphases on network performance at both system level and user level. More specifically, we seek to answer the following two questions: 1) How to model user mobility in the networks and use the model for network provisioning? 2) Is it possible to utilize network diversity to provide robust data transport in wireless environments? We first study user mobility in a large scale wireless network. We propose a mixed queueing model of mobility and show that this model can accurately predict both system-level and user-level performance metrics. Furthermore, we demonstrate how this model can be used for network dimensioning. Secondly, with the increasing demand of multi-homed devices that interact with heterogeneous networks such as WiFi and cellular 3G/4G, we explore how to leverage this path diversity to assist data transport. We investigate the technique of multi-path TCP (MPTCP) and evaluate how MPTCP performs in the wild through extensive measurements in various wireless environments using WiFi and cellular 3G/4G simultaneously. We study the download latencies of MPTCP when using different congestion controllers and number of paths under various traffic loads and over different cellular carriers. We further study the impact of short flows on MPTCP by modeling MPTCP\u27s delay startup mechanism of additional flows. As flow sizes increase, we observe that traffic in cellular networks exhibits large and varying packet round trip times, called bufferbloat. We analyze the phenomenon of bufferbloat, and illustrate how bufferbloat can result in numerous MPTCP performance issues. We provide an effective solution to mitigate the performance degradation. Finally, as popular content is replicated at multiple locations, we develop mechanisms that take advantage of this source diversity along with path diversity to provide robust mobile data transport. We demonstrate this in the context of online video streaming, because of its popularity and significant contribution to Internet traffic. We therefore propose MSPlayer, a client-based solution for online video streaming that adjusts network traffic distribution over each path to network dynamics. MSPlayer bypasses the deployment limitations of MPTCP while maintaining the benefits of path diversity, and exploits different content sources simultaneously. MSPlayer can significantly reduce video start-up latency and quickly refill playout buffer for high quality video streaming. We evaluate MSPlayer\u27s performance through YouTube