3Com Switch 4800G 24-Port Configuration Manual page 955

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Configuring NTP The broadcast server periodically sends NTP broadcast messages to the broadcast
Broadcast Mode address 255.255.255.255. After receiving the messages, the switch working in
NTP broadcast mode sends a reply and synchronizes its local clock.
For switches working in the broadcast mode, you need to configure both the
server and clients. Because an interface need to be specified on the broadcast
server for sending NTP broadcast messages and an interface also needs to be
specified on each broadcast client for receiving broadcast messages, the NTP
broadcast mode can be configured only in the specific interface view.
Configuring a broadcast client
To do...
Enter system view
Enter interface view
Configure the switch to work
in the NTP broadcast client
mode
Configuring the broadcast server
To do...
Enter system view
Enter interface view
Configure the switch to work
in the NTP broadcast server
mode
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A broadcast server can synchronize broadcast clients only after its clock has been
synchronized.
Configuring NTP The multicast server periodically sends NTP multicast messages to multicast clients,
Multicast Mode which send replies after receiving the messages and synchronize their local clocks.
For switches working in the multicast mode, you need to configure both the server
and clients. The NTP multicast mode must be configured in the specific interface
view.
Configuring a multicast client
To do...
Enter system view
Typically, at least one of the symmetric-active and symmetric-passive peers has
been synchronized; otherwise the clock synchronization will not proceed.
You can configure multiple symmetric-passive peers by repeating the
ntp-service unicast-peer command.
Configuring the Operation Modes of NTP
Use the command...
system-view
interface interface-type
interface-number
ntp-service
broadcast-client
Use the command...
system-view
interface interface-type
interface-number
ntp-service
broadcast-server
[ authentication-keyid keyid
| version number ]*
Use the command...
system-view
955
Remarks
-
Required
Enter the interface used to
receive NTP broadcast
messages
Required
Remarks
-
Enter the interface used to
send NTP broadcast messages
Required
Remarks
-