Configuring Ntp Access Restrictions - Cisco Catalyst 4500 series Administration Manual

Managing the System Time and Date
To configure the switch to receive NTP broadcast packets from connected peers, perform this task:
Command
Step 1
configure terminal
Step 2
interface interface-id
Step 3
ntp broadcast client
Step 4
exit
Step 5
ntp broadcastdelay microseconds
Step 6
end
Step 7
show running-config
Step 8
copy running-config startup-config
To disable an interface from receiving NTP broadcast packets, use the no ntp broadcast client interface
configuration command. To change the estimated round-trip delay to the default, use the
no ntp broadcastdelay global configuration command.
This example shows how to configure a port to receive NTP broadcast packets:
Switch# configure terminal
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# ntp broadcast client
Switch(config-if)# end
Switch#

Configuring NTP Access Restrictions

You can control NTP access on two levels as described in these sections:
•
•
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
4-8
Purpose
Enters global configuration mode.
Specifies the interface to receive NTP broadcast packets, and enter
interface configuration mode.
Enables the interface to receive NTP broadcast packets.
By default, no interfaces receive NTP broadcast packets.
Returns to global configuration mode.
(Optional) Changes the estimated round-trip delay between the switch and
the NTP broadcast server.
The default is 3000 microseconds; the range is 1 to 999999.
Returns to privileged EXEC mode.
Verifies your entries.
(Optional) Saves your entries in the configuration file.
Creating an Access Group and Assigning a Basic IP Access List, page 4-9
Disabling NTP Services on a Specific Interface, page 4-10
Chapter 4 Administering the Switch
OL-30933-01