H3C S5500-EI series Operation Manual page 1158

Operation Manual – NTP
H3C S5500-EI Series Ethernet Switches
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
(broadcast mode). Clients listen to the broadcast messages from servers. After 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.
IV. Multicast mode
Figure 1-6 Multicast mode
In the 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. After 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 the multicast
client mode and continues listening to multicast messages, and synchronizes its local
clock based on the received multicast messages.
Note:
In symmetric peers mode, broadcast mode and multicast mode, the client (or the
symmetric active peer) and the server (the symmetric passive peer) can work 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.
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Chapter 1 NTP Configuration