TCP/IP通信の接続性と性能の監視手法に関する研究

摘要

Recently, since communication services based on the Internet technology, such as IPtelephony, Video on demand (VoD) and electronic commerce, have been widelydeployed, the user requirements for the quality of IP networks become higher. IPtelephony service is expected to be provided with the same quality level as that ofcircuit switching technology, and the standardizations that aims at IP networkperformance objectives, All IP technology and NGN (Next Generation Network) areprogressing. In these circumstances, the establishment of the technologies thatcaptures customers’ communication qualities effectively using network and transportlayers’ communication protocols is required by carriers and ISPs (Internet ServiceProviders).However, a large number of communications is transferred on the provider’s networkfrom various terminals such as mobile terminals and PCs of consumers and servers ofcontents providers. The individual customers and applications may require differentquality levels, and their communication durations and traffic volume may be alsodifferent and various. It is not easy to investigate the link that includes thecommunication traffic for specified users, since the provider’s network is large andseveral network equipments and the links are interconnected complicatedly. Therefore,it is difficult for network operators to capture the states of individual communicationsin detail and appropriately.In order to analyze communications on a large IP network, various tools andrealization methods are proposed according to the unit of the communication and thepurpose of the monitoring. The monitoring methods for the communication between apair of users mainly aim at the analysis of network troubles on a single communicationflow and the inter-connectivity testing between communication systems. For thesepurposes, the format of each packet is analyzed using some protocol analyzers.However, there were issues that these analyzers rely on the operator’s burden for theanalysis related to the correspondences between several packets that areindispensable to the estimation of internal behaviors of the communication systems,and they cannot produce exceptional behaviors that do not conform to the specification.And then, the monitoring methods for the traffic on a link mainly use tools that collectflow statistics related to IP layer traffic such as NetFlow collector. The issue is that thestatistics do not include the statistics related to the IP quality. Moreover, as themonitoring methods for routing information that focuses on overall network, publiclyavailable routing information provided by RouteViews and RIPE projects are used forresearch purposes. However, there are issues that the information is not provided inreal time and it takes unignorable time to analyze routing information because it is notwell-designed for later analysis.From the above considerations, this paper proposes totally five realization methodsaccording to the purposes and the application areas from three approaches. The firstapproach is to monitor communication between a pair of users. It includes tworealization methods, which are the traffic analyzer that estimates TCP behaviorsbased on the analysis between the monitored packets and the TCP tester that testsexceptional TCP sequences using test scenarios. The second approach is to monitor thetraffic on a link. It includes one realization method, which is the performance monitorthat monitors statistics including user quality in real time. The third approach is tomonitor the routing information on overall network. It includes two realizationmethods, which are the analysis method for BGP instability location using a singleobservation point and the high-performance BGP route search system based on anSQL database.This paper clarifies the scope and targets of the proposed approaches and theirrealization methods. Besides, the detailed designs, the implementations and theexperiments from practical point of view are also given in order to evaluate theeffectiveness of proposed methods. Furthermore, it discusses the scope and role of theproposals considering the technical trends from the time when the research was doneand to the current age.