Operation Manual – NTP
H3C S3100 Series Ethernet Switches
Chapter 1 NTP Configuration
1-2
Note:
z
The clock stratum determines the accuracy, which ranges from 1 to 16. The stratum
of a reference clock ranges from 1 to 15. The clock accuracy decreases as the
stratum number increases. A stratum 16 clock is in the unsynchronized state and
cannot serve as a reference clock.
z
The local clock of an S3100 Ethernet switch cannot be set as a reference clock. It
can serve as a reference clock source to synchronize the clock of other devices only
after it is synchronized.
1.1.2 Implementation Principle of NTP
Figure 1-1
shows the implementation principle of NTP.
Ethernet switch A (Device A) is connected to Ethernet switch B (Device B) through
Ethernet ports. Both having their own system clocks, they need to synchronize the
clocks of each other through NTP. To help you to understand the implementation
principle, we suppose that:
z
Before the system clocks of Device A and Device B are synchronized, the clock of
Device A is set to 10:00:00 am, and the clock of Device B is set to 11:00:00 am.
z
Device B serves as the NTP server, that is, the clock of Device A will be
synchronized to that of Device B.
z
It takes one second to transfer an NTP message from Device A to Device B or
from Device B to Device A.
