Mr M. Grigoriev (FERMILAB, USA)
Large, distributed HEP collaborations, such as D0, CDF and US-CMS, depend on stable and robust network paths between major world research centers. The evolving emphasis on data and compute Grids increases the reliance on network performance. FermiLab's experimental groups and network support personnel identified a critical need for WAN monitoring to ensure the quality and efficient utilization of such network paths. This has led to the development of the Network Monitoring system we will present in this paper. The system evolved from the IEPM-BW project, started at SLAC two years ago. At Fermilab it has developed into a fully functional infrastructure with bi-directional active network probes and path characterizations. It is based on the Iperf achievable throughput tool, Ping and Synack to test ICMP/TCP connectivity, Pipechar and Traceroute to test, compare and report hop-by-hop network path characterization, and real file transfer performance by BBFTP and GridFTP. The Monitoring system has an extensive web-interface and all the data is available through standalone SOAP web services or by a MonaLISA client. Also in this paper we will present a case study of network path asymmetry and abnormal performance between FNAL and SDSC which was discovered and resolved by utilizing the Network Monitoring system.