Network Time Protocol (NTP) is a program memory protocol used for time synchronization between hosts on a TCP / IP network. The goal of NTP is to make sure that all devices in a network match in time, because even a small difference can cause problems. NTP uses a client-server architecture. usually with a host configured as an NTP server and other hosts on the network configured as NTP clients.
Cisco routers can be configured as both NTP clients and NTP servers. To configure a Cisco router as an NTP client, you can use the ntp server IP_ADDRESS command:
Floor1 (config) # ntp server 192.168.0.100
NOTE
To define a version of NTP, add the NUMBER version keywords at the end of the command (for example, ntp server 192.168.0.100 version 3).
Use the Show NTP Status command to check the NTP status:
Floor1 # Show NTP status
The clock is synchronized, layer 2, the reference is 192.168.0.100
nominal frequency is 250.0000 Hz, the actual frequency is 249.9999 Hz, the accuracy is 2 ** 19
Reference time is DE4AB2B7.0000037A (18: 49: 27.890 UTC Thursday, April 5, 2018)
The clock offset is 0.00 ms, the basic delay is 0.00 ms
The root scatter is 0.02 ms, the propagation is 0.02 ms.
To configure your Cisco router as an NTP server, only one command is required:
DEVICE (config) #ntp master