Operation Manual – NTP
H3C S3610&S5510 Series Ethernet Switches
Chapter 1 NTP Configuration
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replies from the servers, the client performs clock filtering and selection, and
synchronizes its local clock to that of the optimal reference source.
In this mode, a client can be synchronized to a server, but not vice versa.
II. Symmetric peers mode
Figure 1-4
Symmetric peers mode
A device working in the symmetric active mode periodically sends clock
synchronization messages, with the Mode field in the message set to 1 (symmetric
active); the device that receives this message automatically enters the symmetric
passive mode and sends a reply, with the Mode field in the message set to 2
(symmetric passive). By exchanging messages, the symmetric peers mode is
established between the two devices. Then, the two devices can synchronize, or be
synchronized by, each other. If the clocks of both devices have been already
synchronized, the device whose local clock has a lower stratum level will synchronize
the clock of the other device.
III. Broadcast mode
Figure 1-5
Broadcast mode
In the broadcast mode, a server periodically sends clock synchronization messages to
the broadcast address 255.255.255.255, with the Mode field in the messages set to 5
