Campus Network Performance Monitoring System Based On Traffic Analysis

With the development of internet technology, many new applications such as VoIP,video conference, online game have become more and more popular. Users demandhigher performance of Internet than before to guarantee their using experience. In thetrend, Service Level Agreement also includes performance guarantee clause, whichrequires internet operator can measure and monitor the performance of end-to-endcommunication on small granularity. Traditionally, the tools embedded in router andswitcher, such as SNMP, NetFlow, can analyze network traffic, load and transmittingperformance, but can’t measure and monitor end-to-end performance.Currently, most of Internet operator actively send test packet to get end-to-endperformance between certain nodes, then estimate the performance of the wholenetwork link by network chromatography. But the performance of individualapplication and session not only depend on network general statistic performance, butalso depend on the status of terminal nodes of the link. It is necessary to implementend-to end performance measurement on small granularity to guarantee user experience.But in large-scale LAN, there are many concurrent session and nodes. Activemeasurement which needs to inject large amount of test traffic into the network willimpact on users’ data traffic, and also lacks expandability. At the same time, theobjective of active measurement is the whole external network, which makes it hard toselect effective measurement nodes.According to above problem, this paper researches network communication processwhich is based on TCP protocol, analyzes passive performance measurement indifferent scenarios such as TCP connection establishment, sliding window control,retransmission, delayed-ACK, proposes measurement process and the method whichcan modify and optimize measurement results.This paper proposes TCP orientation passive performance measurement solution,designs the way to identify TCP session reassemble and retransmission, analyzes thedifference of communication performance between multiple TCP sessions in the sameIP address, and comes up with a method on how to aggregate TCP sessions based on IPaddress.Finally, this paper verifies the research result by testing in Tsinghua UniversityCampus network. Author deploys measurement prototype system on Tsinghua University Campus network to prove the usability of the system. According to themeasurement results, this paper analyzes strengths and weaknesses of using mid-valueand mean value for measurement. This paper completes aggregation analysis ofTsinghua University Campus network external performance based on IP address, aswell as different application communication performance analysis based on port number.Turn out that TCP retransmission rate is much larger than packet loss rate. According tothe results, this paper analyzes TCP retransmission is mainly because of out-order, notpacket loss.