Network Time Protocol (NTP) is a protocol for synchronizing computer clocks on a network. This protocol is an application protocol responsible for synchronizing hosts on a TCP/IP network. NTP synchronizes the time of day between a number of distributed time servers and clients whereas many applications require synchronized time. An NTP server typically receives time from an authoritative time source. Like an atomic clock connected to a time server, it then distributes that time over the network.
To read more about NTP, please refer to the article Network Time Protocol (NTP).
Steps to Configure and Verify NTP Operating in a client & server mode in cisco packet tracer:
Step 1: First, open the cisco packet tracer desktop and select the devices given below:
| S.NO | Device | Model name | Qty. |
|---|---|---|---|
| 1. | Switch | PT-Switch | 1 |
| 2. | Router | PT-Router | 2 |
| 3. | Server | Server-PT | 1 |
IP Addressing Table
| S.NO | Device | Interface | IPv4 Address | Subnet Mask |
|---|---|---|---|---|
| 1. | Server-PT | nil | 209.165.200.225 | 255.255.255.0 |
| 2. | router0 | GigabitEthernet0/0 | 209.165.200.226 | 255.255.255.0 |
| 3. | router1 | GigabitEthernet0/0 | 209.165.200.227 | 255.255.255.0 |
- Then, create a network topology as shown below the image.
- Use an Automatic connecting cable to connect the devices with others.
Step 2: Configure the Server, and both routers with IPv4 address and Subnet Mask according to the IP addressing table above.
- To assign an IP address to a device, click on the device.
- Then, go to desktop and then IP configuration and there you will IPv4 configuration.
- Fill IPv4 address and subnet mask.
Step 3: Verify the NTP server configuration by pinging the IP address of the server in Router0 and Router1.
- Click on router0 and go to CLI
- To check the configuration of the NTP server type ping 200.165.200.225
- As we can see in the below images we are getting a 100% success rate.
Step 4: Now we have to configure router0 and router1 as NTP clients.
- We will use NTP server command to specify an NTP server in global configuration mode
CLI command :
Router>en Router#conf t Enter configuration commands, one per line. End with CNTL/Z. Router(config)#ntp server 209.165.200.225
- Repeat the same procedure with Router1
- Now NTP status is enabled and we can check it with the show ntp status command
Step 5: Verify NTP settings
- Check the clock settings on Router0 and Router1 to check whether they are synchronized or not.
For router0
Router#show clock detail 19:30:42.376 UTC Wed Jun 22 2022 Time source is NTP
For router1
Router#show clock detail 19:30:42.376 UTC Wed Jun 22 2022 Time source is NTP
Check the NTP status
- Use the show ntp status command to check whether the clock is synchronized or not.
Router#show ntp status Clock is synchronized, stratum 16, reference is 209.165.200.225 nominal freq is 250.0000 Hz, actual freq is 249.9990 Hz, precision is 2*24 reference time is 1D4B418D.0000023C (14:15:41.572 UTC Sat Oct 14 2051) clock offset is 0.00 msec, root delay is 0.00 msec root dispersion is 54.97 msec, peer dispersion is 0.12 msec. loopfilter state is 'CTRL' (Normal Controlled Loop), drift is - 0.000001193 s/s system poll interval is 4, last update was 7 sec ago. Router#