Configuring Cisco Devices to Use an NTP Server

You can use NTP to synchronize time on a variety of devices including networking equipment. I have included the necessary NTP commands for a variety of Cisco Systems products, because it is one of the most popular manufacturers of networking equipment and would feature in the overall architectures of many small office/home office (SOHO) environments and corporate departments.

Cisco IOS

To make your router synchronize with NTP servers with IP addresses 192.168.1.100 and 192.168.1.201, use the commands:

     ciscorouter> enable
     password: *********
     ciscorouter# config t
     ciscorouter(config)# ntp update-calendar
     ciscorouter(config)# ntp server 192.168.1.100
     ciscorouter(config)# ntp server 192.168.1.201
     ciscorouter(config)# exit
     ciscorouter# wr mem

The ntp server command forms a server association with another system, and ntp update-calendar configures the system to update its hardware clock from the software clock at periodic intervals.

CAT OS

To make your router synchronize with NTP servers with IP addresses 192.168.1.100 and 192.168.1.201, use the commands:

     ciscoswitch> enable
     password: *********
     ciscoswitch# set ntp client enable
     ciscoswitch# ntp server 192.168.1.100
     ciscoswitch# ntp server 192.168.1.201
     ciscoswitch# exit

The ntp server command forms a server association with another system, and set ntp client enable activates the NTP client.