NTP – Configuration Example

As we discussed about NTP in last post, here I want to show you NTP basic commands and configuration examples for Maipu routers.

Basic NTP Commands

Command	Description	Configuration Mode
ntp master [stratum-number]	*To configure the NTP server and specify the stratum number	config
ntp server [vrf vrf-name] ip-address | domain-name [version version][key key-number] [source interface-name]	*To configure the NTP client and specify the server address, version, key and source interface.	config
ntp authenticate	*To authenticate the NTP clock source	config
ntp authentication-key key-number md5 key	*To configure the NTP authentication key	config
ntp trusted-key key-number	*To configure the trusted key of the NTP client	config
ntp access-group peer access-list-number	To configure the NTP access control list	config
ntp source interface-name	To specify the NTP source interface	config
ntp enable	To enable the NTP function	config
no ntp	To disable the NTP and clear the configuration	config

Configuration example -

 Description: The interface (3.3.3.1) of the local router (router-1) is connected to the interface (3.3.3.2) of the peer router (router-2). The router-1 serves as the server and the router-2 serves as the client.

Router-1 configuration:

Command	Description
router(config)#ntp master	To enable the NTP server
router(config)#ntp authentication-key 1 md5 maipu	To configure the authentication key as 1 and key content as maipu

Router-2 configuration:

Command	Description
router(config)#ntp authentication-key 1 md5 maipu	To configure the authentication key as 1 and key content as maipu
router(config)#ntp trusted-key 1	To configure the trusted key as 1
router(config)#ntp authenticate	To enable the NTP authentication function
router(config)#ntp server 3.3.3.1 key 1	To configure the server address as 3.3.3.1 and the key as 1

This above example is with MD5 authentication. We can do simple configuration also with MD5. Just configure ntp master in server router and ntp server x.x.x.x (NTP server IP)  in client Router.

Monitoring Commands

Command	Description
show ntp status	To display the current NTP status, including stratum and reference time
show clock	To display the current system time and check whether the time is synchronized correctly

Monitoring Command Example

show ntp status

Displayed Result	Description and Analysis
Current NTP status information Clock is synchronized, stratum 3, reference is 128.255.40.145 reference time is BC17C9CE.E22220B3 (00:33:18.883 Sat Jan 01 2011)	The clock is synchronized. The reference source address is 128.255.40.145. The time is 00:33: 18, Jan. 1, 2011.

show clock 

Displayed Result	Description and Analysis
UTC SAT JAN 01 00:37:07 2011	The system time is 00:37:07, Jan 1, 2011.

Debugging Commands

Command	Description
(no) debug ntp events | packet	To enable/disable the NTP event and packet debugging switch

Hope this example will help you for NTP configuration reference.

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