H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – NTP
H3C S7500E Series Ethernet Switches Chapter 1 NTP Configuration
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Chapter 1 NTP Configuration
When configuring NTP, go to these sections for information you are interested in:
z NTP Overview
z Configuring the Operation Modes of NTP
z Configuring the Local Clock as a Reference Source
z Configuring Optional Parameters of NTP
z Configuring Access-Control Rights
z Configuring NTP Authentication
z Displaying and Maintaining NTP
z NTP Configuration Examples
1.1 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.
1.1.1 Applications of NTP
An administrator can by no means keep synchronized time among all the devices within
a network by changing the system clock on each station, because this is a huge amount
of workload and cannot guarantee the clock precision. NTP, however, allows quick
clock synchronization within the entire network while it ensures a high clock precision.
NTP is used when all devices within the network must be consistent in timekeeping, for
example:
z In analysis of the log information and debugging information collected from
different devices in network management, time must be used as reference basis.
z All devices must use the same reference clock in a charging system.
z To implement certain functions, such as scheduled restart of all devices within the
network, all devices must be consistent in timekeeping.
z When multiple systems process a complex event in cooperation, these systems
must use that same reference clock to ensure the correct execution sequence.
z For increment backup between a backup server and clients, timekeeping must be
synchronized between the backup server and all the clients.