7-6
Catalyst 2928 Switch Software Configuration Guide
OL-23389-01
Chapter 7 Administering the Switch
Managing the System Time and Date
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
Configuring NTP Broadcast Service
The communications between devices running NTP (known as
associations
) are usually statically
configured; each device is given the IP addresses of all devices with which it should form associations.
Accurate timekeeping is possible by exchanging NTP messages between each pair of devices with an
association. However, in a LAN environment, NTP can be configured to use IP broadcast messages
instead. This alternative reduces configuration complexity because each device can simply be configured
to send or receive broadcast messages. However, the information flow is one-way only.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
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.
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config
Verify your entries.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
