2002 - cesnet

20 NTP Server Linked to the NationalTime StandardThe objective of the project is to build and operate a time server bound to thenational time standard. The server was created as the result of the collaborationof CESNET and the Institute of Radio Engineering and Electronics of theAcademy of Sciences of the Czech Republic (Ústav radiotechniky a elektronikyAkademie věd České republiky), which is responsible for the National Timeand Frequency Standard.20.1 Functional Components of theServerThe server, as a whole, is a system which does not only provide time informationvia the network, but also checks itself using the time standard with theaccuracy of more than 1 microsecond and compares its time with other independentsources – a GPS receiver and an external time server. If a suspicion ofa malfunction or improper functioning arises, the provision of time informationto the network is blocked. We have applied a strictly defensive approach andour basic thesis states “better no time data provisioning than potentially inaccuratedata“.The server is formed by three basic functional blocks:• NTP computer• KPC control system• FK microprocessor system20.2 NTP ComputerThe NTP computer is the most essential component of the entire system. Thentpd process (version 4.1.71) is running in this computer. The process synchronizesthe internal time with the external signal and delivers time information toclients via the NTP protocol. In addition, time information is also provided viathe TIME and DAYTIME protocols.From the hardware viewpoint, this computer is a standard PC (Pentium III1.2 GHz), in which a new oscillator and a special card for processing the PPSsignal were installed. The computer is equipped with two network adapters(10/100 Mbps Ethernet) – one with a public IP address, one for peer-to-peer com-200 High-speed National Research Network and its New Applications 2002