How to Configure Network Time Protocol on GNS3

Configure Network Time Protocol on GNS3

Before you start

Objectives : You will able to understand & configure NTP (Network Time Protocol) on GNS3.
Prerequisite : You need GNS3 GNS3 Simulator.
Tags : NTP, GNS Configuration, CISCO.

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NTP Baisc

NTP stand for Network Time Protocol. The main use of NTP is to provide accurate time to all the client machine or network devices. Many time, our requirement is to set a particular time on all devices, then NTP is the simplest protocol which provide same time to all the devices which request for time to NTP Server.
In this article, we are going to understand and configure NTP on CISCO Router. We will set the time on one Router and make this router NTP Server, so that all the NTP client request for time to NTP Server, and NTP Server will provide accurate time to all NTP client machine.

Configure one interface to communicate with different NTP client

Here, first of all we are going to configure Router Interface, which is used to communicate with different NTP client. In this case i will take fastethernet interface, you can take any interface. I'll show the configuration of only one router. Rest of two routers are also have IP in same range i.e R2=>192.168.1.2, R3=>192.168.1.3 .

configure terminal
interface FastEthernet 0/0
ip address 192.168.1.1 255.255.255.0
no shutdown

Set the clock according to current time

Now, we will set the time on this router using following commands.

R1#clock set 20:53:50 22 Jan 2018

Make this router as NTP Server

Now, we will make this router as NTP server, so it will listen NTP request and reply same time (i.e. Router itself time).

R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#ntp master

Set all other network devices as NTP client

Now, we will set all other network devices as NTP client. All NTP client request for time to NTP Server. We will use following command to configure NTP Client. You can use the same command on Router 3.

R2#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#ntp server 192.168.1.1

Now, if someone force to change the time on NTP Client Device, then it will automatic synchronize according to NTP Server.

R2#clock set 10:10:10 15 NOV 1995
*Nov 15 10:10:10.000: %SYS-6-CLOCKUPDATE: System clock has been updated from 21:01:56 UTC Mon Jan 22 2018 to 10:10:10 UTC Wed Nov 15 1995, configured from console by console.
R2#show clock
21:01:28.899 UTC Mon Jan 22 2018

IF you have any difficulty to use NTP Server, please comment in comment box. :)