Configuring Ntp - Cisco Catalyst 2950 Software Configuration Manual

Chapter 7 Administering the Switch
Figure 7-1
Local
workgroup
servers
Workstations
If the network is isolated from the Internet, Cisco's implementation of NTP allows a device to act as
though it is synchronized through NTP, when in fact it has determined the time by using other means.
Other devices then synchronize to that device through NTP.
When multiple sources of time are available, NTP is always considered to be more authoritative. NTP
time overrides the time set by any other method.
Several manufacturers include NTP software for their host systems, and a publicly available version for
systems running UNIX and its various derivatives is also available. This software allows host systems to
be time-synchronized as well.

Configuring NTP

The switch does not have a hardware-supported clock, and it 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.
This section contains this configuration information:
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78-11380-12
Typical NTP Network Configuration
Switch B
Switch E
Switch F
Workstations
Default NTP Configuration, page 7-4
Configuring NTP Authentication, page 7-4
Configuring NTP Associations, page 7-5
Switch A
Switch C
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
Managing the System Time and Date
Switch D
7-3