H3C Technologies H3C SecBlade LB Cards - Manual (Page 131)

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Typically, the stratum level of the NTP server that is synchronized from an authoritative clock (such as an
atomic clock) is set to 1. This NTP server operates as the primary reference source on the network, and
other devices synchronize to it. The number of NTP hops that devices in a network are away from the
primary reference source determines the stratum levels of the devices.
If you configure the local clock as a reference clock, the local device can act as a reference clock to
synchronize other devices in the network. Perform this configuration with caution to avoid clock errors in
the devices in the network.
To configure the local clock as a reference source:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the local clock as a
reference source. ntp-service refclock-master
[ ip-address ] [ stratum ]
The value of the ip-address argument
must be 127.127.1.u, where the value
range for u is 0 to 3, representing the
NTP process ID.
Configuring optional parameters for NTP
This section explains how to configure the optional parameters of NTP.
Specifying the source interface for NTP messages
If you specify the source interface for NTP messages, the device sets the source IP address of the NTP
messages as the primary IP address of the specified interface when sending the NTP messages. NTP
packets might not be received because of state changes of an interface on the device. To avoid that
problem, specify the loopback interface as the source interface.
When the device responds to an NTP request received, the source IP address of the NTP response is
always the destination IP address of the NTP request.
Follow these guidelines when you configure the source interface for NTP messages:
• The source interface for NTP unicast messages is the interface specified in the ntp-service
unicast-server or ntp-service unicast-peer command.
• The source interface for NTP broadcast or multicast messages is the interface where you configure
the ntp-service broadcast-server or ntp-service multicast-server command.
To specify the source interface for NTP messages:
Step Command Remarks
1. Enter system view. system-view N/A
2. Specify the source interface
for NTP messages. ntp-service source-interface
interface-type interface-number
By default, no source interface is
specified for NTP messages, and
the system uses the IP address of
the interface determined by the
matching route as the source IP
address of NTP messages.
Disabling an interface from receiving NTP messages
If NTP is enabled, NTP messages can be received from all the interfaces by default.