Configuring Ntp - Cisco Catalyst 4500 Series Software Configuration Manual

Chapter 4 Administering the Switch
Figure 4-1
C, and D configured in NTP server mode, in server association with Switch A. Switch E is configured
as an NTP peer to the upstream and downstream switches, Switch B and Switch F, respectively.
Figure 4-1
Local
workgroup
servers
Workstations
If the network is isolated from the Internet, Cisco's implementation of NTP allows a device to act as if
it is synchronized through NTP, when it is not. Other devices then synchronize to that device through
NTP.
NTP time overrides the time set by any other method.
Several manufacturers include NTP software for their host systems, and a public version for systems
running UNIX and its various derivatives is also available. This software allows host systems to be
synchronized as well.

Configuring NTP

These sections contain this configuration information:
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shows a typical network example using NTP. Switch A is the NTP master, with Switches B,
Typical NTP Network Configuration
Switch B
Switch E
Switch F
Workstations
Default NTP Configuration, page 4-4
Configuring NTP Authentication, page 4-4
Configuring NTP Associations, page 4-6
Configuring NTP Broadcast Service, page 4-7
Configuring NTP Access Restrictions, page 4-8
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Managing the System Time and Date
Switch A
Switch C Switch D
4-3