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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Data-Link Layer Traceback in Ethernet Networks

Snow, Michael Thomas 07 December 2006 (has links)
The design of the most commonly-used Internet and Local Area Network protocols provide no way of verifying the sender of a packet is who it claims to be. Protocols and applications exist that provide authentication but these are generally for special use cases. A malicious host can easily launch an attack while pretending to be another host to avoid being discovered. At worst, the behavior may implicate a legitimate host causing it and the user to be kicked off the network. A malicious host may further conceal its location by sending the attack packets from one or more remotely-controlled hosts. Current research has provided techniques to support traceback, the process of determining the complete attack path from the victim back to the attack coordinator. Most of this research focuses on IP traceback, from the victim through the Internet to the edge of the network containing the attack packet source, and Stepping-Stone traceback, from source to the host controlling the attack. However, little research has been conducted on the problem of Data-Link Layer Traceback (DLT), the process of tracing frames from the network edge to the attack source, across what is usually a layer-2 network. We propose a scheme called Tagged-fRAme tracebaCK (TRACK) that provides a secure, reliable DLT technique for Ethernet networks. TRACK defines processes for Ethernet switches and a centralized storage and lookup host. As a frame enters a TRACK-enabled network, a tag is added indicating the switch and port on which the frame entered the network. This tag is collected at the network edge for later use in the traceback operation. An authentication method is defined to prevent unauthorized entities from generating or modifying tag data. Simulation results indicate that TRACK provides accurate DLT operation while causing minimal impact on network and application performance. / Master of Science
2

Adaptive Bandwidth Allocation for Wired and Wireless WiMAX Networks

Huang, Kai-chen 09 July 2008 (has links)
In this thesis, we consider a network environment which consists of wired Internet and a wireless broadband network (WiMAX); data from wired or wireless network are all conveyed through WiMAX links to its destination. In order to promise the quality of real-time traffic and allow more transmission opportunity for other traffic types, we propose an Adaptive Bandwidth Allocation (ABA) algorithm for BS to adequately allocate bandwidth. Our ABA algorithm would first reserve required minimum bandwidth for high-priority traffic, such as video streaming. By allocating minimum bandwidth to real-time traffic, the delay time constraint can be satisfied. Other traffic types, such as non-real-time, which have no real-time requirement, may gain extra bandwidth to improve their throughput. For best-effort traffic, the remaining bandwidth can be used to avoid any possible starvation. We build four-dimension Markov chains to evaluate the performance of the proposed ABA algorithm. In the analytical model, we first divide transmission on WiMAX into upload and download phases, and analyze the ABA performance by using Poisson process to generate traffic. At last, by comparing to a previous work, we observe the impacts of different traffic parameters on WiMAX network performance in terms of average delay time, average throughput, and average packet-drop ratio.
3

Assessing the Physical Vulnerability of Backbone Networks

Shivarudraiah, Vijetha 04 April 2011 (has links)
Communication networks are vulnerable to natural as well as man-made disasters. The geographical layout of the network influences the impact of these disasters. It is therefore, necessary to identify areas that could be most affected by a disaster and redesign those parts of the network so that the impact of a disaster has least effect on them. In this work, we assume that disasters which have a circular impact on the network. The work presents two new algorithms, namely the WHF-PG algorithm and the WHF-NPG algorithm, designed to solve the problem of finding the locations of disasters that would have the maximum disruptive effect on the communication infrastructure in terms of capacity.
4

Reliable Communication of Time- and Security-Sensitive Information over a Single Combat Vehicle Network

Nilsson, Håkan January 2019 (has links)
A common trend, in general as well as in the field of combat vehicles, is the rapidly increasing demand for data network capacity and even more in transferred data. To handle this increased demand, different countries with their armed forces and equipment manufacturers evaluate methods to increase the data transmission capacity in combat vehicles. The different types of transmitted data are of different criticality and have different security demands. An easy solution to this is to have separated networks for each type of traffic, but that is quite expensive and uses a lot of hardware. This thesis focuses on a different solution, with a shared network for all types of data transmissions. This is done by evaluating different types of data networks and add-on protocols and then testing the networks practically with varying transmission rates. In the thesis, all the practical testing is done with data networks according to the Ethernet standard, which is the standard evaluated with a throughput that is high enough for the use case. Ethernet as a standard is not suitable for critical data traffic and therefore add-on protocols for Ethernet to optimize the system for critical data traffic are tested. With these optimizations made, Ethernet can be considered more suitable for critical traffic, but this depends entirely on the system requirements.
5

TCP HolyWood

Núñez Mori, Oscar January 2005 (has links)
Apresentamos um novo Protocolo de Controle de Transporte fim-a-fim, implementado somente do lado do transmissor, chamado TCP HolyWood ou, abreviadamente, TCP-HW. Em um ambiente de rede cabeada simulada, TCP HolyWood supera em vazão media três dos mais importantes protocolos TCPs já elaborados. Estamos falando de TCP Reno, TCP Westwood, e TCP Vegas; e em variação de retardo media ao TCP Reno bem como ao TCP Vegas. Alem disso, de acordo com o índice de Jain, nossa proposta e tão imparcial quanto o padrão, TCP Reno. / We introduce a new end-to-end, sender side Transport Control Protocol called TCP HolyWood or in short TCP-HW. In a simulated wired environment, TCP HolyWood outperforms in average throughput, three of the more important TCP protocols ever made, we are talking about TCP Reno, TCP Westwood, and TCP Vegas; and in average jitter to TCP Reno and TCP Vegas too. In addition, according to Jain’s index, our proposal is as fair as TCP Reno, the Standard.
6

TCP HolyWood

Núñez Mori, Oscar January 2005 (has links)
Apresentamos um novo Protocolo de Controle de Transporte fim-a-fim, implementado somente do lado do transmissor, chamado TCP HolyWood ou, abreviadamente, TCP-HW. Em um ambiente de rede cabeada simulada, TCP HolyWood supera em vazão media três dos mais importantes protocolos TCPs já elaborados. Estamos falando de TCP Reno, TCP Westwood, e TCP Vegas; e em variação de retardo media ao TCP Reno bem como ao TCP Vegas. Alem disso, de acordo com o índice de Jain, nossa proposta e tão imparcial quanto o padrão, TCP Reno. / We introduce a new end-to-end, sender side Transport Control Protocol called TCP HolyWood or in short TCP-HW. In a simulated wired environment, TCP HolyWood outperforms in average throughput, three of the more important TCP protocols ever made, we are talking about TCP Reno, TCP Westwood, and TCP Vegas; and in average jitter to TCP Reno and TCP Vegas too. In addition, according to Jain’s index, our proposal is as fair as TCP Reno, the Standard.
7

TCP HolyWood

Núñez Mori, Oscar January 2005 (has links)
Apresentamos um novo Protocolo de Controle de Transporte fim-a-fim, implementado somente do lado do transmissor, chamado TCP HolyWood ou, abreviadamente, TCP-HW. Em um ambiente de rede cabeada simulada, TCP HolyWood supera em vazão media três dos mais importantes protocolos TCPs já elaborados. Estamos falando de TCP Reno, TCP Westwood, e TCP Vegas; e em variação de retardo media ao TCP Reno bem como ao TCP Vegas. Alem disso, de acordo com o índice de Jain, nossa proposta e tão imparcial quanto o padrão, TCP Reno. / We introduce a new end-to-end, sender side Transport Control Protocol called TCP HolyWood or in short TCP-HW. In a simulated wired environment, TCP HolyWood outperforms in average throughput, three of the more important TCP protocols ever made, we are talking about TCP Reno, TCP Westwood, and TCP Vegas; and in average jitter to TCP Reno and TCP Vegas too. In addition, according to Jain’s index, our proposal is as fair as TCP Reno, the Standard.
8

Gateway Adaptive Pacing for TCP across Multihop Wireless Networks and the Internet

ElRakabawy, Sherif M., Klemm, Alexander, Lindemann, Christoph 17 December 2018 (has links)
In this paper, we introduce an effective congestion control scheme for TCP over hybrid wireless/wired networks comprising a multihop wireless IEEE 802.11 network and the wired Internet. We propose an adaptive pacing scheme at the Internet gateway for wired-to-wireless TCP flows. Furthermore, we analyze the causes for the unfairness of oncoming TCP flows and propose a scheme to throttle aggressive wired-to-wireless TCP flows at the Internet gateway to achieve nearly optimal fairness. Thus, we denote the introduced congestion control scheme TCP with Gateway Adaptive Pacing (TCP-GAP). For wireless-to-wired flows, we propose an adaptive pacing scheme at the TCP sender. In contrast to previous work, TCP-GAP does not impose any control traffic overhead for achieving fairness among active TCP flows. Moreover, TCP-GAP can be incrementally deployed because it does not require any modifications of TCP in the wired part of the network and is fully TCP-compatible. Extensive simulations using ns-2 show that TCPGAP is highly responsive to varying traffic conditions, provides nearly optimal fairness in all scenarios and achieves up to 42% more goodput than TCP NewReno.
9

TCP with gateway adaptive pacing for multihop wireless networks with Internet connectivity

ElRakabawy, Sherif M., Klemm, Alexander, Lindemann, Christoph 17 December 2018 (has links)
This paper introduces an effective congestion control pacing scheme for TCP over multihop wireless networks with Internet connectivity. The pacing scheme is implemented at the wireless TCP sender as well as at the Internet gateway, and reacts according to the direction of TCP flows running across the wireless network and the Internet. Moreover, we analyze the causes for the unfairness of oncoming TCP flows and propose a scheme to throttle aggressive wired-to-wireless TCP flows at the Internet gateway to achieve nearly optimal fairness. The proposed scheme, which we denote as TCP with Gateway Adaptive Pacing (TCP-GAP), does not impose any control traffic overhead for achieving fairness among active TCP flows and can be incrementally deployed since it does not require any modifications of TCP in the wired part of the network. In an extensive set of experiments using ns-2 we show that TCP-GAP is highly responsive to varying traffic conditions, provides nearly optimal fairness in all scenarios and achieves up to 42% more goodput for FTP-like traffic as well as up to 70% more goodput for HTTP-like traffic than TCP NewReno. We also investigate the sensitivity of the considered TCP variants to different bandwidths of the wired and wireless links with respect to both aggregate goodput and fairness.
10

Error Resilient Coding Using Flexible Macroblock Ordering In Wired And Wireless Communications

Demirtas, Ali Murat 01 September 2008 (has links) (PDF)
Error Resilient Coding tools are the methods to avoid or reduce the amount of corruption in video by altering the encoding algorithm. One of them is Flexible Macroblock Ordering (FMO) which provides us with ordering macroblocks of the frames flexibly. Six of them have definite ordering pattern and the last one, called explicit type, can get any order. In this thesis two explicit type algorithms, one of which is new, are explained and the performance of different FMO types in wired and wireless communication are evaluated. The first algorithm separates the important blocks into separate packets, so it equalizes the importance of packets. The proposed method allocates the important macroblocks according to a checkerboard pattern and employs unequal error protection to protect them more. The simulations are performed for wired and wireless communication and Forward Error Correction is used in the second stage of the simulations. Lastly the results of the new algorithms are compared with the performance of the other FMO types. According to the simulations the Proposed algorithm performs better than others when the error rate is very high and FEC is employed.

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