Gorgy Timing LEDI NETWORK DCLS, User Manual

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73 MDE-LEDInetworkITS-server-4078V1.3
1. INTRODUCTION
The time information exchanged through the network is the UTC Time (GMT+0). A
client (for example a PC) must convert this time using its own time-zone information
(and eventually by applying day saving correction.
The NTP protocol has reserves for security by implementing an encryption system:
each exchanged frame can be encrypted using the protocols DES and MD5.
In addition to the GT NTP client software for Windows, you can found several NTP
client programs for a variety of hardware on the site:
www.ntp.org/software
1.3.2. Synchronization concepts
A/ Clock Correction principles
The objective of the synchronization is to make two clocks indicating the same time.
In the case of NTP based synchronization, the LEDI Network ITS/NTP Server clock
must indicate the same time that the NTP server clock.
To perform this synchronization, the NTP client software permanently compares the
two clocks and computes the following information:
► Offset :
It’s the difference between the time of the server clock and the time of the client
clock. For example, if the server clock indicates 2:10:13 and the client clock indica-
tes 2:11:14, the offset is –1:01.
NTP client
TCP/IP+Ethernet
network
Request time
Return time
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