Configuring Ntp - Cisco Catalyst 4500 Series Configuration Manual

Chapter 4 Administering the Switch
Cisco's implementation of NTP does not support stratum 1 service; it is not possible to connect to a radio
or atomic clock. We recommend that the time service for your network be derived from the public NTP
servers available on the IP Internet.
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:
•
•
OL-25340-01
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
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
Managing the System Time and Date
Switch A
Switch C Switch D
4-3