H3C Technologies H3C SR8800 - Manual (Page 70)

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• Symmetric mode
• Broadcast mode
• Multicast mode
For the client/server mode or symmetric mode, you need to configure only clients or symmetric-active
peers; for the broadcast or multicast mode, you need to configure both servers and clients.
NOTE:
A single router can have a maximum of 128 associations at the same time, including static associations
and dynamic associations. A static association refers to an association that a user has manually created
by using an NTP command, while a dynamic association is a temporary association created by the system
during operation. A dynamic association will be removed if the system fails to receive messages from it
over a specific long time. In the client/server mode, for example, when you carry out a command to
synchronize the time to a server, the system will create a static association, and the server will just respond
passively upon the receipt of a message, rather than creating an association (static or dynamic). In the
symmetric mode, static associations will be created at the symmetric-active peer side, and dynamic
associations will be created at the symmetric-passive peer side; in the broadcast or multicast mode, static
associations will be created at the server side, and dynamic associations will be created at the client side.
Configuring NTP client/server mode
For routers working in the client/server mode, make the following configurations on the clients.
To configure an NTP client:
Step Command Remarks
1. Enter system view. system-view N/A
2. Specify an NTP server for the
router.
ntp-service unicast-server
[ vpn-instance vpn-instance-name ]
{ ip-address | server-name }
[ authentication-keyid keyid |
priority | source-interface
interface-type interface-number |
version number ] *
No NTP server is specified by
default.
NOTE:
•
In the ntp-service unicast-server command, ip-address must be a unicast address, rather than a
broadcast address, a multicast address or the IP address of the local clock.
• When the source interface for NTP messages is specified by the source-interface argument, the source
IP address of the NTP messages is configured as the primary IP address of the specified interface.
• A router can act as a server to synchronize the clock of other routers only after its clock has been
synchronized. If the clock of a server has a stratum level higher than or equal to that of a client’s clock,
the client will not synchronize its clock to the server’s.
• You can configure multiple servers by repeating the ntp-service unicast-server command. The clients
will choose the optimal reference source.