Principles; Operating Principle - Huawei AR150 Series Configuration Manual

Huawei AR150&200&1200&2200&3200 Series Enterprise
Routers
Configuration Guide - Device Management
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5.2 Principles

This section describes the implementation of NTP.

5.2.1 Operating Principle

Figure 5-1
RouterA and RouterB are connected through a wide area network (WAN). Each of them has its
own system clock, which is synchronized automatically through NTP.
Presuming that:
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Issue 05 (2014-01-16)
Date Proto Description
col
Num
ber
Septemb RFC NTPv2 supports authentication and control messages.
er 1989 1119
March RFC NTPv3 uses correctness principles and improves clock selection
1992 1305 and filter algorithms, and it is widely used.
June RFC NTPv3 only applies to an IPv4 network. As IPv6 develops and
2010 5905 network security requirements grow, NTPv4 is produced. NTPv4,
an extension of NTPv3, is compatible with NTPv3.
l NTPv4 applies to both IPv4 and IPv6 networks.
l NTPv4 provides a complete encryption and authentication
shows NTP implementation:
Before the clocks of RouterA and RouterB are synchronized, the clock of RouterA is
10:00:00 a.m. and the clock of RouterB is 11:00:00 a.m.
RouterB acts as an NTP time server, and RouterA must synchronize its clock with that of
RouterB.
It takes one second to unidirectionally transmit an NTP message between RouterA and
RouterB.
Both RouterA and RouterB take one second to process an NTP message.
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system so it is more secure than NTPv3.
5 NTP Configuration
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