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1、网络测量概念及主流方法（Concepts and mainstream methods of network measurement）Network measurementCatalogmeasureFour elements of measurementResearch field of network measurementNetwork measurement classificationResearch directionEdit this paragraphmeasureMeasurement is based on a certain law, using data to desc
2、ribe the observed phenomenon, that is, quantitative description of things. Measurement is the quantification process of non quantifiable physical objects.Edit this paragraphFour elements of measurement1, measuring objects, that is, the object of measurement. It is the object or phenomenon in the obj
3、ective world, and it is the object that we should use figures or symbols to express, explain and explain.2, measure content, namely measure a kind of attribute or characteristic of the object. In fact, in any measurement, the object we measure is an object, but the content is not the object itself,
4、but the characteristic or attribute of the object.3. The rules of measurement, that is, the use of numbers and symbols to represent various attributes or characteristics of foods. It can also be said that it is a specific operating procedure and a criterion for distinguishing different characteristi
5、cs or attributes.4, numbers and symbols, that is used to represent the results of measurement tools. Such as 120cm, 350 yuan. ?Edit this paragraphResearch field of network measurementNetwork measurement and analysis is mainly divided into 3 research areas:(1) measurement data accurately and quantita
6、tively capture the Internet activities. Usually, network measurement of the main parameters including RTT, data path, bandwidth, delay, bottleneck, bursty traffic congestion degree, frequency, dynamic bottleneck, site accessibility, throughput, bandwidth utilization, packet loss rate, and server the
7、 network device response time, maximum network traffic, the network service quality QoS (quality including images, data, voice and other services). It is necessary to point out that in the measurement of the network level, a class of properties need to be measured is inherent in the network, such as
8、 its topology, connection capacity, delay the other; the class attribute reflects the current state of the network, such as queuing delay, dynamic routing and connection availability. (2) model. This is the core issue of performance evaluation, establish a formal description and Simulation of the ne
9、twork. The effective application of the model can predict the future network behavior(3) control. Using the obtained from measuring and modeling knowledge, realize the rational allocation of resources and the use of the Internet. Network topology measurement, the dynamic description of the large sca
10、le network structure, and analyze the performance of the network according to the network change, the network efficiency andThe evaluation of behavior has at least the following applications:(1) network monitoring. Including the operation of network monitoring, network monitoring and performance of
11、the cyber source (such as throughput, delay, packet loss rate, RTT, bandwidth utilization and network scalability (scalability) etc.) monitoring, and submit fault and abnormal event report, make the corresponding evaluation.(2) network quality control and auxiliary network management, such as discov
12、ering and correcting ill conditioned routing, routing policy according to long observed route data, network resource self-organization after network disruption, etc.(3) to prevent large-scale network attacks, network traffic analysis and mapping and provide necessary information for attacks against.
13、 Through network behavior monitoring in large range, is likely to find network anomaly, provide early warning means to prevent large-scale network attacks, the state of network management more macro control.(4) the network measurement can be applied to different Internet service provider (Internet s
14、ervice provider, referred to as ISP) quality of service (quality of service, referred to as QoS), is the location of the mobile IP, the proxy server automatic selection and many other aspects.(5) provide the research foundation for simulation, Internet environment, protocol design and evaluation, an
15、d dynamic network storage activity analysis(6) to provide the basis, auxiliary basis and verification platform for Internet Traffic Engineering (Traffic Engineering) and network behavior (network behavior) researchEdit this paragraphNetwork measurement classificationThere are several kinds of classi
16、fication standard of network measurement. According to the measurement methods, divided into active and passive measurement; according to the number of measurement points, divided into single point measurement and multi-point measurement; according to the measure of informed and not divided into coo
17、perative measurement and non cooperative measurement; according to the measurement protocol used, divided based on the measurement, based on the BGP protocol of TCP/IP protocol and the measurement measurement based on SNMP protocol; according to the measurement of the content, divided into topology
18、measurement and performance measurement.In the active measurement mode, by sending data in the network, the observations and the time needed for sending data to study the behavior of the network. The active traffic measurement to the network to send the actual use, these reflect the network traffic
19、measurement to provide parameters to other users of the service, including round-triptime (RTT) and packet loss rate. Now, most people do the projects are related to active measurement.In passive measurement,The probes that record network activity are accessed into the network, and in most cases, th
20、ey are connected to connections between network nodes, summarizing and recording the traffic traffic on that connectionFrom the number of measurement points, network measurement is divided into single point and multi-point measurement. At the beginning of the study, many work belong to the single po
21、int measurement, but because the measurement capability is limited, the information collected is not comprehensive, distributed multi-point measurement came into being, especially more active measurement, using multiple detection point data obtained can cross the routing information network data sca
22、le and a single point of income to the single point test. A typical example is the Baer Laboratory of the InternetMapping project, which is a non cooperative measurement. The project successfully describes the topology changes of Kosovo during the war in Yugoslavia and Kosovo two network, which show
23、s that in IP network measurement, single point measurement of non cooperation has a very strong network detection ability. This is also the network measurement model applied in the military field.In topology measurement, most of the project shows the logical topology diagram. With the expansion of t
24、he scope of measurements, the whole graph scale structure also increases. At this time, people tend to want to correspond with the actual geographical location and topology of.Skitter is geographic information visualization (CAIDA) for from the source point to a few tens of thousands of targets poin
25、t path information collected topology and performance attributes, and carried out the research of geographic information map of AS.In the aspect of performance measurement, more relevant projects, including the measurement of throughput, delay, packet loss rate, and analysis of network reliability,
26、stability, accessibility and other aspects. On the one hand to a specific network maintenance and management, ensure the quality of service; on the other hand, in order to predict the performance of network, such as NPACI s Network Weather Service5 at a certain time interval, periodic monitoring and
27、 dynamic forecast (all kinds of network and computing resources) network performance. A time of data collection, the end-to-end throughput and delay by numerical model to predict the next time TCP/IP, mainly used for large-scale calculation of the wide area network scheduling.Edit this paragraphRese
28、arch direction(1) IP. The main topology measurement measurement methods are divided into two categories: Based on the SNMP protocol, based on the ICMP protocol. The former mainly through access MIB library topological relation, because right, suitable for jurisdiction within the scope of the network
29、 measurement with, so it is difficult to application. The latter can be realized by Tracert. For large-scale network measurement on the Internet, but when the network is installed on the firewall software, it can not be measured. Process is as follows: first to get IP address network segment, then t
30、he route tracking technology to get a packet from the source IP address to the IP address of all the IP address of the router, all IP address for a network routing tracking, the router will get all the IP address of the network and the Internet. Route tracing technology is based on the principle of
31、the following: first, using TTL= to achieve 1 to an unreachable port of destination IP addresses (usually more than 10000 ports) with a UDP packet, the packet after the first router, the router will be discarded at the same time, the router will send a ICMP packet to the source host to notify the pa
32、cket loss by unlocking the ICMP package, you can get the IP address of the router. Then, well take TTL=2 to the destination IP address to send UDP packets, repeat the above operation, until the return of the ICMP packet type to port unreachable, that has reached the destination host, so you get from
33、 the machine to the main machine through the IP address of the router. At present. All routers support this implementation. According to the data collected by the path table module, can directly generate IP routing topology reflect the logical connection, with the IP location, can generate City cove
34、r Cap topology(2) AS topology measurement. In general, the method of generating AS level topology graph can be attributed to BGP routing information based on the Traceroute AS map, AS map and based on some characteristics of the topology generator synthesis (synthesizing) AS level topology graph thr
35、ee. Among them, first kinds of methods are generally the method. A passive measurement and active measurement two measurement modes are available. The former gets BGP packets in the key nodes, then using finite state automaton technology, BGP processing of update packet capture; the latter owned a r
36、outer running BGP protocol, through consultation with the ISP, the establishment of BGP peer connection with the corresponding router. Only receives the routing update messages, forwarding user data, which requires both sides to properly configure the corresponding peer router. Based on a large amou
37、nt of measured data, generate AS topology connection graph. By AS topology connection graph We can understand each AS connection relationship intuitively, and analyze which AS plays an important role, which can not only provide guidance for new AS access,It can also provide guidance for computer att
38、ack and defense in future information warfare(3) measurement and analysis of network performance based on TCP/IP protocol. In order to investigate the network stability, accessibility, reliability and quality of service, for continuous measurement of periodicity, the performance parameters such as p
39、acket loss rate, RTT, flow path, average number of hops; on this basis, the analysis of the dynamic changes of time as the main line on the path of each index, with space for the overall situation the main statistical analysis at a certain time of the whole network, such as the magnitude at differen
40、t delay node overall number distribution, analysis of end-to-end routing changes (routing changes or hops). Other analysis also includes the detection of the data (data data mining mining), or by using the existing model (Petri, self similarity, queuing theory) to study the self similar characterist
41、ics. Because of the high real-time requirement of network performance measurement, so the detection frequency is very large, but You must ensure that you do not cause significant additional load on the network, while keeping track of hidden traces(4) a comprehensive analysis of the network operation
42、. Multiple monitoring points based on the measurement data collected in different period, comprehensive situation generating measured network strategy map, realizing strategizing and winning thousands of miles away. The map in addition to having different levels of attributes of the instant playback
43、 function, but also through the color mark and the voice prompts, traffic anomaly, fault alarm, provide early warning means to prevent large-scale network attacks at the same time, from the view of network attack, covert, efficient distributed network reconnaissance measurement method research and d
44、evelopment. In addition, a comprehensive analysis, QoS index, for the user to provide first-hand reports of sick routing, based on the network after the destruction of the cyber source for correct routing, network routing strategy formulation of morbid and self-organization.(5) visual measurement an
45、d analysis results. The visualization of network measurement and analysis is a key link. Through the study, the use of graphical user interface GUI, electronic map, map zoom, drag the arbitrary multilayer representation, histogram, 2D and 3D coordinates curve, pie charts, forms, reports, 2D graphic,
46、 three-dimensional graphics 8 a variety of methods, combined with GIS technology, the trend map hierarchy, drag, interactive hierarchical display, intuitive and image to show the results. Compromise is that it is necessary to fully display the data in the library objectively, but also has a good vis
47、ual effect.(6) prediction of network behavior modeling, network simulation, network topology discovery and measurement. The trend has become the main method of network behavior, network behavior measurement is the basis of the behavior of the whole network. Modeling of network behavior analysis usin
48、g queuing theory, Petri net, Markov chain, Poisson process due to theory. Internet, the change of the environment complexity and heterogeneity of modeling and simulation analysis of network behavior become said of an aged person.(7) architecture of network measurement. With the passage of time, the network measurement will continue to upgrade, so in the design at the beginning of the implementation, it is necessary to fully consider the measurement system scalability, scalable and compatibility, fault tolerance.?