Network Architecture - Huawei AR150 Series Configuration Manual

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

5.2.2 Network Architecture

The NTP network architecture involves the following concepts:
l
l
l
l
Figure 5-2 NTP network architecture
Secondary time server
Secondary time server
Under normal circumstances, the primary time server and the secondary time servers in a
synchronization subnet are arranged in a hierarchical-master-slave structure. In this structure,
the primary time server is located at the root, and the secondary time servers are arranged close
to leaf nodes. As their strata increase, the precision decreases accordingly. The extent to which
the precision of the secondary time servers decreases depends on stability of network paths and
the local clock.
NOTE
Such a design ensures that:
Issue 05 (2014-01-16)
Synchronization subnet consists of the primary time server, secondary time servers, PC
clients, and interconnecting transmission paths, as shown in
Primary time server directly synchronizes its clock with a standard reference clock using
a cable or radio. The standard reference clock is usually a radio clock or the Global
Positioning System (GPS).
Secondary time server synchronizes its clock with the primary time server or other
secondary time servers on the network. A secondary time server transmits the time
information to other hosts on a LAN through NTP.
Stratum is a hierarchical standard for clock synchronization. It represents precision of a
clock. The value of a stratum ranges from 1 to 16. A smaller value indicates higher precision.
The value 1 indicates the highest clock precision, and 16 indicates that the clock is not
synchronized.
RouterB
stratum2
stratum3
PC1
When the synchronization subnet has multiple primary time servers, the optimal server can be selected
using an algorithm.
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RouterA
Primary time server
stratum1
RouterC RouterE
PC2
5 NTP Configuration
Figure 5-2.
RouterD
Secondary time server
stratum2
Secondary time server
stratum3
PC3 PC4
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