A Measurement Of Quality Of Internet End-To-End Services

The fast spread of Internet has made the stability and high quality of its services become more and more important. Such facts make it more important to measure the Internet precisely. Only learn about the actual state of a network, can we configure and allocate the resources more reasonably, which also is the basic task to help the network operators improve the quality of service.The dependence of most network applications, such as Internet video services and FTP file transfer services, are not two-way. They are more likely to rely on only one-side of the quality. Hence, we can derive two-way network quality from one-way network quality, but not the other way around. But it’s much harder to measure one-way network quality. The basic one among them is time synchronization of computers, but this is only a start. There are other problems, such as the correspondence of sending and receiving packets via passive measurement, process and analyze the huge number of captured packets via long time measurement.In order to catch the real running status in a network, the measure system should affect the network as little as possible. Passive measurement, or non-intrusive measurement, gets the network status by capturing data packages in the network. PCAP library can help to capture packets and get receiving and sending timestamp of the packets. A lot of devices in the Internet are located in a closed LAN, and the communications with outer networks are done through NAT feature of the gateway using shared outgoing IP. As NAT protocol will change the header of network layer and transmission layer, one-way network measurement could not recognize the correspondence between packages been sent and received. Such problem is solved by modifying the protocol field and calculating the summary of the whole package to be its ID.The intranet IP will also be changed into outer net IP, the package capturing program should use the outer net IP to do the address filtering. All the filtered packets are communication packets between the two hosts. By setting up a TCP connect, we can get the outer net IP of the remote host.Network measuring needs long-time running to monitor the communication between two end-to-end hosts, which will produce large amount of data, a repeating labeling and segments computation algorithm is introduced to solve the problems of large data analysis.A passive measurement system has been designed and implemented, which measured the one-way network metrics between alibaba cloud computer network and China Education and Research Network, and verified the correctness of the provided solutions.