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Disabling NTP on an Interface
By default, NTP is enabled on all active interfaces. If you disable NTP on an interface, the system drops any
NTP packets sent to that interface.
To disable NTP on an interface, use the following command.
•
Disable NTP on the interface.
INTERFACE mode
ntp disable
To view whether NTP is configured on the interface, use the show config command in INTERFACE mode. If
ntp disable is not listed in the show config command output, NTP is enabled. (The show config
command displays only non-default configuration information.)
Configuring a Source IP Address for NTP
Packets
By default, the source address of NTP packets is the IP address of the interface used to reach the network.
You can configure one interface's IP address include in all NTP packets.
To configure an IP address as the source address of NTP packets, use the following command.
•
Configure a source IP address for NTP packets.
CONFIGURATION mode
ntp source interface
Enter the following keywords and slot/port or number information:
•
For a loopback interface, enter the keyword loopback then a number between 0 and 16383.
•
For a port channel interface, enter the keyword lag then a number from 1 to 255.
•
For a 10-Gigabit Ethernet interface, enter the keyword TenGigabitEthernet then the slot/port
information.
•
For a 40-Gigabit Ethernet interface, enter the keyword fortyGigE then the slot/port information.
•
For a port extender (PE) 1 Gigabit Ethernet interface, enter the keyword peGigE then the pe-id/pe-
stack—unit-id/port-number information. The pe-id range is from 0 to 255; the stack unit number
range is from 0 to 7; and the port—ID range is from 1 to 48.
•
For a VLAN interface, enter the keyword vlan then a number from 1 to 4094.
To view the configuration, use the show running-config ntp command in EXEC privilege mode (refer to
the example in
Configuring NTP
Authentication).
System Time and Date
1106
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Table of Contents
Troubleshooting
