H3C Technologies H3C S3100 Series Switches - Manual (Page 464)

Operation Manual – NTP
H3C S3100-52P Ethernet Switch 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 S3100-52P Ethernet switch cannot operate as a reference
clock. It can serve as a NTP server only after synchronized.
1.1.2 Implementation Principle of NTP
Figure 1-1 shows the implementation principle of NTP.
Ethernet switch A (LS_A) is connected to Ethernet switch B (LS_B) through Ethernet
ports. Both have their own system clocks, and 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 LS_A and LS_B are synchronized, the clock of LS_A
is set to 10:00:00 am, and the clock of LS_B is set to 11:00:00 am.
z
LS_B serves as the NTP server, that is, the clock of LS_A will be synchronized to
that of LS_B.
z
It takes one second to transfer an NTP packet from LS_A to LS_B or from LS_A to
LS_B.