R3721-F3210-F3171-HP High-End Firewalls System Management and Maintenance Configuration Guide-6PW101

101
NTP configuration task list
Task Remarks
Configuring the NTP operation modes Required
Configuring the local clock as a reference source Optional
Configuring optional NTP parameters Optional
Configuring access-control rights Optional
Configuring NTP authentication Optional
Configuring the 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.
Configuration guidelines
• A single device 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.
• A dynamic association is a temporary association created by the system during operation. A
dynamic association is removed if the system fails to receive messages from it over a specific long
time.
• In client/server mode, for example, when you execute a command to synchronize the time to a
server, the system creates a static association, and the server simply responds passively upon the
receipt of a message, rather than creating an association (static or dynamic). In symmetric mode,
static associations are created at the symmetric-active peer side, and dynamic associations are
created at the symmetric-passive peer side. In broadcast or multicast mode, static associations are
created at the server side, and dynamic associations are created at the client side.
Configuring the NTP client/server mode
Configuration guidelines
• If you specify the source interface for NTP messages by specifying the source interface
source-interface option, NTP uses the primary IP address of the specified interface as the source IP
address of the NTP messages.
• A device can act as a server to synchronize the clock of other devices 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.