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Example of Configuring NTP Broadcasts
2w1d11h : NTP: Maximum Slew:-0.000470, Remainder = -0.496884
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 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).
Configuring NTP Authentication
NTP authentication and the corresponding trusted key provide a reliable means of exchanging NTP
packets with trusted time sources.
NTP authentication begins when the first NTP packet is created following the configuration of keys. NTP
authentication in Dell Networking OS uses the message digest 5 (MD5) algorithm and the key is
embedded in the synchronization packet that is sent to an NTP time source.
Dell Networking OS Behavior: Dell Networking OS uses an encryption algorithm to store the
authentication key that is different from previous Dell Networking OS versions; Dell Networking OS uses
data encryption standard (DES) encryption to store the key in the startup-config when you enter the ntp
authentication-key
command. Therefore, if your system boots with a startup-configuration from an
888
System Time and Date