H3C Technologies H3C MSR 50 - Manual (Page 38)

Configuring NTP
You must synchronize your device with a trusted time source by using the Network Time Protocol (NTP) or
changing the system time before you run it on a live network. Various tasks, including network
management, charging, auditing, and distributed computing depend on an accurate system time setting,
because the timestamps of system messages and logs use the system time.
Overview
NTP is typically used in large networks to dynamically synchronize time among network devices. It
guarantees higher clock accuracy than manual system clock setting. In a small network that does not
require high clock accuracy, you can keep time synchronized among devices by changing their system
clocks one by one.
NTP runs over UDP and uses UDP port 123.
NTP application
An administrator is unable to keep time synchronized among all the devices within a network by
changing the system clock on each station, because this is a huge work and does not guarantee clock
precision. NTP, however, allows quick clock synchronization within the entire network and ensures a high
clock precision.
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 the same
reference clock to ensure the correct execution sequence.
• For incremental backup between a backup server and clients, timekeeping must be synchronized
between the backup server and all the clients.
NTP advantages
• NTP uses a stratum to describe clock precision, and it can synchronize time among all devices
within the network.
• NTP supports access control and MD5 authentication.
• NTP can unicast, multicast or broadcast protocol messages.
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