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Top2. Background
Taiwan Advanced Research and Education Network (Taiwan Advanced Research and Education Network [TWAREN], n. d.) is a national research and education network in Taiwan and has been upgraded to the 100G technology in October 2016. TWAREN backbone consists of five core nodes and twelve GigaPOPs. The five core nodes are located in Academia Sinica, National Academy for Education Research (NAER), and the Hsinchu, Taichung and Tainan office of National Center for High-performance Computing. The twelve GigaPOPs include NTU, NCU, NTHU, NCTU, NCHU, NCNU, CCU, NCKU, NSYSU, NDHU, NIU and NCCU, each connecting to two core nodes with 20 Gbps to 50 Gbps bandwidth, as shown in Figure 1. The TWAREN member institutions, including universities, research organizations and regional network centers, connects to TWAREN GigaPOPs with 1 Gbps dedicate circuits or metropolitan area network (MAN). The international research and education network connection is provided by two 10 Gbps links going to Los Angeles and Chicago. TWAREN provides services such as IPv4, IPv6, VPLS VPN, SSLVPN and SDN testbed.
Figure 1. TWAREN 100G backbone architecture
Network performance measurement provides detailed and comprehensive information to assist the network operator to pinpoint the location and the root cause of the network problem in a quicker and more efficient way (Zurawski et al, 2013). The accuracy of a network performance measurement system depends on the tools it used to perform the measurement, the tuning and optimization of the system and the experience the engineer has. This paper introduces how the measurement servers deployed in the TWAREN GigaPOPs are established and used in the server based network performance measurement. It also introduces how to use the open source tools developed by Internet2(Internet2, n. d.) to setup a network measurement platform and how it can contribute to network problem diagnosis when combining the power of a PHP written weathermap. In the section three the active network measurement is briefly explained. In the section four, the network measurement tools being used in this paper and the weathermap technology are introduced. Section five depicts the architecture of the TWAREN perfSONAR system. Section six explains the data acquisition and analysis program and the section seven elaborates the architecture and method used to combine the perfSONAR measurement with the weathermap technology.
Top3. Active Network Measurement
In order to detect the real-time status of the network, servers have been deployed to key locations of the network. This kind of network measurement is often referred to as a server based network performance measurement. In current TWAREN measurement architecture, perfSONAR toolkit has been installed to server machines and then the servers deployed to all core nodes and GigaPOPs. All severs have direct connection to backbone routers. Through the TWAREN backbone, each pair of the perfSONAR servers routinely makes measurement such that a fully mesh network measurement coverage is achieved. The measurement contains ping test (for round trip delay measurement) and one way ping (for one way packet loss measurement). The bandwidth measurement can also be included if necessary. In order to have an accurate measure over the one way ping, the time of the servers need to be precisely calibrated by NTP service to have matching time ticks. The server based measurement results will be automatically stored in each perfSONAR measurement archives, and then fetched by the self-developed data collector program in five minutes interval. The results from all perfSONAR servers are then merged and converted to the format suitable for TWAREN NOC(Network Operation Center) monitoring and alerting service. Eventually the combined data will be stored in the TWAREN NOC monitoring databases.