Configuring Ntp Associations - Cisco Catalyst 4500 series Administration Manual

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).
To form an NTP association with another device, perform this task:
Command
Step 1
configure terminal
Step 2
ntp peer ip-address
[ ] [
key keyid source interface
[ ]
prefer
or
ntp server ip-address
] [
number key keyid
] [
interface prefer
Step 3
end
Step 4
show running-config
Step 5
copy running-config startup-config
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# configure terminal
Switch(config)# ntp server 172.16.22.44 version 2
Switch(config)# end
Switch#
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
4-6
Purpose
Enters global configuration mode.
[ ]
Configures the switch system clock to synchronize a peer or to be
version number
]
synchronized by a peer (peer association).
or
[
version
Configures the switch system clock to be synchronized by a time server
] [
source
(server association).
]
No peer or server associations are defined by default.
•
•
•
•
•
Returns to privileged EXEC mode.
Verifies your entries.
(Optional) Saves your entries in the configuration file.
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 by entering
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.
Chapter 4 Administering the Switch
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