published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

通訊與資訊科技的大幅進步，電信自由化帶來的激烈競爭，以及網際網路的蓬勃發展，刺激大量多媒體網路資訊的流通，為了因應此種趨勢，網路提供者已趨向合併數據及電信網路朝單一的All-IP網路方向發展。為了保證時效性服務在All-IP網路上的品質，網路服務品質(QoS)已成為All-IP網路的主要研究議題。不同的網路應用各有不同的特性與需求；對於那些比較不注重傳輸延遲時間的應用，增加網路頻寬或許就已足夠應付需求，但是對於那些具有互動特性 (interactive)、重視傳輸延遲時間的應用，像VoIP，除了增加網路頻寬外，All-IP網路必須提供服務品質保證才能獲得網路營運者的支持。本研究團隊設計一個管理架構，在此架構上提供完整的End-to-End QoS保證，以符合All-IP網路上各種不同服務需求。本文中另外提出以預先批購頻寬的方式進行核心網路資源規劃，根據需求預測，考量批購成本期望值，決定出適當之頻寬預購值。於執行時段提出數個允入控制資源不足解決方案，並且配合執行時段頻寬管理機制，掌握頻寬使用情形，以達到順利允入網路訊務之目的。最後於NS2平台以實驗模擬的方式，評估本文中所提出之預先批購頻寬與執行時段頻寬管理機制，從結果中我們發現本研究所提出之頻寬預購方法可以有效預防因為預測誤差所造成之資源不足現象，配合執行時段頻寬管理機制可根據執行時期之資源使用狀況，在資源缺乏時提前進行頻寬補充，以順利允入訊務，提升使用率。 / Because of great progress of communication and computer technology, aggressive deployment of broadband fiber optical network, advance of Internet technology, and the global standardization of IP technology, the telecommunication industry is moving toward a converged network, which uses a single global IP based packet-switching network to carry all types of network traffics. In these types of network traffics, different traffic types require corresponding service to ensure end- to-end quality. For carrying all types of network traffics on All-IP network, BBQ (Budget-Based QoS) research group propose a QoS system architecture to provide end-to-end QoS guarantee. In this thesis, basing on BBQ QoS system, we propose resource pre-planning mechanism to management core network. According to demand forecast from historical data and considering pre-planning cost, pre-planning mechanism will find optimal policy to reduce management cost. Besides resource pre- planning, we also propose several solutions to avoid resource shortage at run-time. Through intensive evaluation in network simulatior-2(ns2), we demonstrate that our resource pre-planning can minimize resource cost and cover some forecasting error. And run-time resource management can maintain reasonable in-hand resource at run-time to reduce the effect of resource shortage.

O projeto VoIPFix surgiu da necessidade de uma ferramenta que complementasse as demais existentes no ramo de análise de redes de computadores para telefonia IP. Ele foi construído para ser uma ferramenta de gerenciamento eficiente e exclusiva para VoIP, com funcionalidades necessárias para dar suporte ao profissional de rede de computadores e telefonia IP a observar e diagnosticar problemas de VoIP. / The VoIPFix project arose from the need for a tool to complement similar tools in the analysis of computer networks for IP telephony. It was built to be an efficient and unique management tool for VoIP, with advanced features required to support the computer network and IP telephony professionals to observe and diagnose problems related to VoIP.

This paper discusses current network technologies and protocols and presents a simulation study of the most common networking protocol used today, TCP/IP. The TCP/IP protocol stack has many inherent problems that will be shown through this simulation study. Using the SimpleScalar Toolset, the significance of the data copying and checksumming performed in TCP/IP will be shown along with the architecture needed to support the processing of TCP/IP. Solutions for these TCP/IP pitfalls including a zero-copy protocol and a design for an intelligent network interface card will also be presented. / Graduation date: 2000

IP address lookup is an important processing function of Internet routers. The challenge lies in finding the longest prefix that matches the packets destination address. One of the issues concerning IP address lookups is the average lookup time. In previous works, caching was shown to be an effective method to minimize the average lookup time. Caching involves storing information on recent IP lookup results in order to decrease average lookup times. In this thesis, we present two architectures that contain a prefix cache and a dynamic substride cache. The dynamic substride cache stores longest possible substrides from previous lookups, and is used in conjunction with a prefix cache. Successful hits in both the caches help reduce the number of worst-case lookups in the low level memory containing the IP routing table in a trie data structure. From simulations, we show that the two architectures show up to 99.9%global hit rate. Furthermore we present analytical models to find optimal designs for the two architectures. We also show that the architectures can support incremental updates once appropriate modifications are made to the trie data structure.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Sterners Specialfabrik AB tillverkar bland annat mynt- och biljettautomater. För att underlätta felsökning, underhåll, avläsning av statistik med mera på en automat är det lämpligt att detta utförs på en PC över Internet. Det innebär att automaten inte behöver besökas då dessa uppgifter skall utföras. Examensarbetet går ut på att få en PIC mikrokontroller att kommunicera med en användare vid en PC över internet. För detta krävs att en TCP/IP stack implementeras på PICmikrokontrollern. Arbetet ledde till en fungerande demoapplikation som klarar av att kommunicera över TCP/IP. Demoapplikationen innehåller diverse olika funktioner för att demonstrera hur en automat skulle kunna styras och övervakas.

Botnet is the biggest threaten now. Botmasters inject bot code into normal computers so that computers become bots under control by the botmasters. Every bot connect to the botnet coordinator called Command and control server (C&C), the C&C delivers commands to bots, supervises the states of bots and keep bots alive. When C&C delivers commands from the botmasters to bots, bots have to do whatever botmasters want, such as DDoS attack, sending spam and steal private information from victims. If we can detect where the C&C is, we can prevent people from network attacking. Ant Colony Optimization (ACO) studies artificial systems that take inspiration from the behavior of real ant colonies and which are used to solve discrete optimization problems. When ants walk on the path, it will leave the pheromone on the path; more pheromone will attract more ants to walk. Quick convergence and heuristic are two main characteristics of ant algorithm, are adopted in the proposed approach on finding the C&C node. According to the features of connection between C&C and bots, ants select nodes by these features in order to detect the location of C&C and take down the botnet.

The work presented in this thesis is motivated by the dual goal of developing a scalable and efficient approach for IP lookup using both hardware and software approach. The work involved designing algorithms and techniques to increase the capacity and flexibility of the Internet. The Internet is comprised of routers that forward the Internet packets to the destination address and the physical links that transfer data from one router to another. The optical technologies have improved significantly over the years and hence the data link capacities have increased. However, the packet forwarding rates at the router have failed to keep up with the link capacities. Every router performs a packet-forwarding decision on the incoming packet to determine the packet??s next-hop router. This is achieved by looking up the destination address of the incoming packet in the forwarding table. Besides increased inter-packet arrival rates, the increasing routing table sizes and complexity of forwarding algorithms have made routers a bottleneck in the packet transmission across the Internet. A number of solutions have been proposed that have addressed this problem. The solutions have been categorized into hardware and software solutions. Various lookup algorithms have been proposed to tackle this problem using software approaches. These approaches have proved more scalable and practicable. However, they don??t seem to be able to catch up with the link rates. The first part of my thesis discusses one such software solution for routing lookup. The hardware approaches today have been able to match up with the link speeds. However, these solutions are unable to keep up with the increasing number of routing table entries and the power consumed. The second part of my thesis describes a hardware-based solution that provides a bound on the power consumption and reduces the number of entries required to be stored in the routing table.

Licentiatavhandling (sammanfattning) Karlstad : Karlstads universitet, 2009. / Härtill 4 uppsatser.