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7-4
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 7 Administering the Switch
Managing the System Time and Date
Configuring NTP
The switch does not have a hardware-supported clock and cannot function as an NTP master clock to
which peers synchronize themselves when an external NTP source is not available. The switch also has
no hardware support for a calendar. As a result, the ntp update-calendar and the ntp master global
configuration commands are not available.
These sections contain this co
nfiguration information:
• Default NTP Configuration, page 7-4
• Configuring NTP Authentication, page 7-4
• Configuring NTP Associations, page 7-5
• Configuring NTP Broadcast Service, page 7-6
• Configuring NTP Access Restrictions, page 7-8
• Configuring the Source IP Address for NTP Packets, page 7-10
• Displaying the NTP Configuration, page 7-11
Default NTP Configuration
Table 7-1 shows the default NTP configuration.
NTP is enabled on all interfaces by default. A
ll interfaces receive NTP packets.
Configuring NTP Authentication
This procedure must be coordinated with the administrator of the NTP server; the information you
configure in this procedure must be matched by the servers used by the switch to synchronize its time to
the NTP server.
Beginning in privileged EXEC mode, follow these steps to authenticate the associations (communications
b
etween devices running NTP that provide for accurate timekeeping) with other devices for security
purposes:
Ta ble 7-1 Default NTP Configuration
Feature Default Setting
NTP authentication Disabled. No authenticati
on key is specified.
NTP peer or server associations None configured.
NTP broadcast service Disabled; no interface sends or receives NTP broadcast packets.
NTP access restrictions No access control is specified.
NTP packet source IP address The source address is set by the outgoing interface.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
ntp authenticate Enable the NTP authentication feature, which is disabled by
default.