3com WX3000 Manuel D’Utilisation

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Multicast mode 
Figure 1-5 Multicast mode 
Client
Multicast clock synchronization 
packets periodically
Network
Server
Initiates a client/server mode 
request after receiving the 
first multicast packet
Works in the server mode 
automatically  and sends 
responses
Client/server mode 
request
Response
Obtains the delay between the 
client and server and works in 
the multicast client mode
Receives multicast packets and 
synchronizes the local clock
Multicast clock synchronization 
packets periodically
 
 
 describes how the above mentioned NTP modes are implemented on the device. 
Table 1-1 NTP implementation modes on the device 
NTP implementation 
mode 
Configuration on the device 
Server/client mode 
Configure the local device to work in the NTP client mode. In this mode, 
the remote server serves as the local time server, while the local device 
serves as the client. 
Symmetric peer mode 
Configure the local device to work in NTP symmetric peer mode. In this 
mode, the remote server serves as the symmetric-passive peer of the 
device, and the local device serves as the symmetric-active peer. 
Broadcast mode 
Configure the local device to work in NTP broadcast server mode. In 
this mode, the local device broadcasts NTP messages through the 
VLAN interface configured on the device. 
Configure the device to work in NTP broadcast client mode. In this 
mode, the local device receives broadcast NTP messages through the 
VLAN interface configured on the device. 
Multicast mode 
Configure the local device to work in NTP multicast server mode. In 
this mode, the local device sends multicast NTP messages through 
the VLAN interface configured on the device. 
Configure the local device to work in NTP multicast client mode. In this 
mode, the local device receives multicast NTP messages through the 
VLAN interface configured on the device. 
 
 
When the device works in server mode or symmetric passive mode, you need not to perform 
related configurations on this device but do that on the client or the symmetric-active peer. 
The NTP server mode, NTP broadcast mode, or NTP multicast mode takes effect only after the 
local clock of the device has been synchronized. 
When symmetric peer mode is configured on two devices, to synchronize the clock of the two 
devices, make sure at least one device’s clock has been synchronized.