3Com Switch 8800 Advanced Software V5 Configuration Guide

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NTP CONFIGURATION
When configuring NTP, go to these sections for information you are interested in:
■ “NTP Overview” on page 1063
■ “Configuring the Operation Modes of NTP” on page 1068
■ “Configuring the Local Clock as a Reference Source” on page 1072
■ “Configuring Optional Parameters of NTP” on page 1072
■ “Configuring Access-Control Rights” on page 1073
■ “Configuring NTP Authentication” on page 1074
■ “Displaying and Maintaining NTP” on page 1076
■ “NTP Configuration Examples” on page 1076
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The term router and the router icons used in this chapter refer to the routers in a
generic sense and the switches running routing protocols.
NTP Overview Defined in RFC 1305, the network time protocol (NTP) synchronizes timekeeping
among distributed time servers and clients. NTP runs over the user datagram
protocol (UDP), using UDP port 123.
The purpose of using NTP is to keep consistent timekeeping among all
clock-dependent devices within the network so that the devices can provide
diverse applications based on the consistent time.
For a local system running NTP, its time can be synchronized by other reference
sources and can be used as a reference source to synchronize other clocks.
Applications of NTP NTP is used when all devices within the network must be consistent in
timekeeping, for example:
■ In analysis of the log information and debugging information collected from
different devices in network management, time must be used as reference
basis.
■ All devices must use the same reference clock in a charging system.
■ To implement certain functions, such as scheduled restart of all devices within
the network, all devices must be consistent in timekeeping.
■ When multiple systems process a complex event in cooperation, these systems
must use that same reference clock to ensure the correct execution sequence.
■ For increment backup between a backup server and clients, timekeeping must
be synchronized between the backup server and all the clients.