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Symmetric peers mode, Broadcast mode – H3C Technologies H3C WX3000E Series Wireless Switches User Manual

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Symmetric peers mode

Figure 8 Symmetric peers mode

In symmetric peers mode, devices that operate in symmetric active mode and symmetric passive mode
exchange NTP messages with the Mode field 3 (client mode) and 4 (server mode). Then the device that

operates in symmetric active mode periodically sends clock synchronization messages, with the Mode

field in the messages set to 1 (symmetric active); the device that receives the messages automatically

enters 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 synchronized, the device whose local clock has a lower stratum level synchronizes the clock

of the other device.

Broadcast mode

Figure 9 Broadcast mode

In broadcast mode, a server periodically sends clock synchronization messages to broadcast address

255.255.255.255, with the Mode field in the messages set to 5 (broadcast mode). Clients listen to the

broadcast messages from servers. When a client receives the first broadcast message, the client and the

server start to exchange messages, with the Mode field set to 3 (client mode) and 4 (server mode) to
calculate the network delay between client and the server. Then, the client enters the broadcast client

mode and continues listening to broadcast messages, and synchronizes its local clock based on the

received broadcast messages.

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