H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 23)

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Multicast mode
Figure 10 Multicast mode
In multicast mode, a server periodically sends clock synchronization messages to the user-configured
multicast address, or, if no multicast address is configured, to the default NTP multicast address 224.0.1.1,
with the Mode field in the messages set to 5 (multicast mode). Clients listen to the multicast messages
from servers. When a client receives the first multicast 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 multicast client mode and continues
listening to multicast messages, and synchronizes its local clock based on the received multicast
messages.
In symmetric peers mode, broadcast mode and multicast mode, the client (or the symmetric active peer)
and the server (the symmetric passive peer) can operate in the specified NTP working mode only after
they exchange NTP messages with the Mode field being 3 (client mode) and the Mode field being 4
(server mode). During this message exchange process, NTP clock synchronization can be implemented.
NTP configuration task list
Task Remarks
Configuring NTP operation modes Required.
Configuring optional parameters for NTP Optional.
Configuring access-control rights Optional.
Configuring NTP authentication Optional.
Configuring NTP operation modes
Devices can implement clock synchronization in one of the following modes:
• Client/server mode—Configure only clients.
• Symmetric mode—Configure only symmetric-active peers.
• Broadcast mode—Configure both clients and servers.
• Multicast mode—Configure both clients and servers.