My Cisco Notes: NTP - Explanation and Configuration

What is NTP?

NTP - Stands for Network Time Protocol.
This allows the network devices to have their clock synchronized with the central Main clock.
NTP gets its time form an authoritative time source usually a radio clock / an atomic clock attached to a time server.
This helps to make sure that all the logs have the correct time stamp.
NTP uses UDP on port 123.

What is NTP Stratum?

NTP stratum refers to the distance between the Network device and the authoritative time source.
Stratum has values between 0-16
stratum 0 refers to the source clock which has little to no delay and cannot be used on the networks.
Stratum 1 is the primary device that gets the time from stratum 0 using GPS or National time and frequency transmission.
The further the stratum level goes the less the accuracy will be.

Lab: Configuring NTP server

Objective: Configure a Router as NTP client and a Server as NTP server for time synchronization.

Topology: NTP Lab – Set up the Packet tracer as above

CONFIGURE THE ROUTER:

Router(config)#hostname Router-1

Router-1(config)#interface fastEthernet 0/0

Router-1(config-if)#ip address 192.168.1.1 255.255.255.0

Router-1(config-if)#no shutdown

Router-1(config-if)#exit

Router-1(config)#exit

Configure the Server:

Assing the IP address on the Server.

Verify the IP address and Ping the Gateway

Enable the NTP service on the server:

//Configure the Router to get the Time from NTP server

Router-1(config)#NTP server 192.168.1.2

Router-1(config)#exit

//Checking the clock after configuring the NTP server

Router-1#show clock

*11:34:29.882 UTC Sun Mar 25 2018

Router-1#

Router-1#show ntp status

Clock is synchronized, stratum 2, reference is 192.168.1.2

nominal freq is 250.0000 Hz, actual freq is 249.9990 Hz, precision is 2**19

reference time is DE3D2144.00000032 (11:49:24.050 UTC Sun Mar 25 2018)

clock offset is 0.00 msec, root delay is 0.00 msec

root dispersion is 0.02 msec, peer dispersion is 0.02 msec.

My Cisco Notes