3Com Switch 7700 Configuration Manual page 371

An interface is specified by interface-name or interface-type interface-number. The
source address of the packets will be taken from the IP address of the interface. If
the ntp-service unicast-server or ntp-service unicast-peer command also
designates a transmitting interface, use the one designated by them.
Setting the NTP Master Clock
This configuration task sets the external reference clock or the local clock as the
NTP master clock.
Perform the following configurations in system view.
Table 75 Setting the External Reference Clock or the Local Clock as the NTP Master Clock
Operation
Set the external reference clock or the local
clock as the NTP master clock.
Cancel the NTP master clock settings
ip-address specifies the IP address 127.127.1.u of a reference clock, in which u
ranges from 0 to 3. stratum specifies how many strata the local clock belongs to
and ranges from 1 to 15. If no IP address is specified, the system defaults to
setting the local clock as the NTP master clock. You can specify the stratum
parameter.
Enabling or Disabling an Interface to Receive an NTP Message
This configuration task enables or disables an interface to receive the NTP
message.
Perform the following configurations in VLAN interface view.
Table 76 Enabling or Disabling an Interface to Receive an NTP Message
Operation
Enable an interface to receive an NTP message undo ntp-service in-interface disable
Disable an interface from receiving an NTP
message
This configuration task must be performed on the interface to be disabled from
receiving an NTP message.
Setting the Authority to Access a Local Switch
Set the authority to access the NTP services on a local switch. This is a basic and
brief security measure. An access request will be matched with peer, serve, serve
only, and query only in an ascending order of the limitation. The first matched
authority will be granted.
Perform the following configurations in system view.
Table 77 Setting the Authority to Access a Local Ethernet Switch
Operation
Set authority to access a local Ethernet switch ntp-service access { query |
Command
ntp-service refclock-master [ ip-address ] [
stratum ]
undo ntp-service refclock-master [
ip-address ]
Command
ntp-service in-interface disable
Command
synchronization | serve | peer } acl-number
NTP 363