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Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
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Chapter8 Administering the Switch
Managing the System Time and Date
Configuring NTP Associations
An NTP association can be a peer association (this switch can either synchronize to the other device or
allow the other device to synchronize to it), or it can be a server association (meaning that only this
switch synchronizes to the other device, and not the other way around).
Beginning in privileged EXEC mode, follow these steps to form an NTP association with another device:
You need to configure only one end of an association; the other device can automatically establish the
association. If you are using the default NTP version (version 3) and NTP synchronization does not
occur, try using NTP version 2. Many NTP servers on the Internet run version 2.
To remove a peer or server association, use the no ntp peer ip-address or the no ntp server ip-address
global configuration command.
This example shows how to configure the switch to synchronize its system clock with the clock of the
peer at IP address 172.16.22.44 using NTP version 2:
Switch(config)# ntp server 172.16.22.44 version 2
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 ntp peer ip-address [version number]
[key keyid] [source interface] [prefer]
or
ntp server ip-address [version number]
[key keyid] [source interface] [prefer]
Configure the switch system clock to synchronize a peer or to be
synchronized by a peer (peer association).
or
Configure the switch system clock to be synchronized by a time server
(server association).
No peer or server associations are defined by default.
•For ip-address in a peer association, specify either the IP address of
the peer providing, or being provided, the clock synchronization. For
a server association, specify the IP address of the time server
providing the clock synchronization.
•(Optional) For number, specify the NTP version number. The range is
1 to 3. By default, version 3 is selected.
•(Optional) For keyid, enter the authentication key defined with the
ntp authentication-key global configuration command.
•(Optional) For interface, specify the interface from which to pick the
IP source address. By default, the source IP address is taken from the
outgoing interface.
•(Optional) Enter the prefer keyword to make this peer or server the
preferred one that provides synchronization. This keyword reduces
switching back and forth between peers and servers.
Step3 end Return to privileged EXEC mode.
Step4 show running-config Verify your entries.
Step5 copy running-config startup-config (Optional) Save your entries in the configuration file.