Ntp Default Configuration; Configuring Ntp On The Switch - Cisco WS-C6506 Software Manual

NTP Default Configuration

The communications between the machines running NTP, known as associations, are usually statically
configured; each machine is given the IP address of all machines with which it should form the
associations. Accurate timekeeping is possible by exchanging the NTP messages between each pair of
machines with an association. However, in a LAN environment, you can configure NTP to use the IP
broadcast messages. With this alternative, you can configure the machine to send or receive the broadcast
messages, but the accuracy of timekeeping is marginally reduced because the information flow is
one-way only.
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 you obtain the time service for your network from the public NTP
servers that are available in the IP Internet. If the network is isolated from the Internet, Cisco's NTP
implementation allows a machine to be configured so that it acts as though it is synchronized using NTP,
when in fact it has determined the time using other means. Other machines then synchronize to that
machine using NTP.
A number of 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
time-synchronized host systems.
NTP Default Configuration
Table 34-1
Table 34-1
Feature
Broadcast client mode
Client mode
Broadcast delay
Time zone
Offset from UTC
Summertime adjustment
NTP server
Authentication mode

Configuring NTP on the Switch

These sections describe how to configure NTP:
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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
34-2
shows the default NTP configuration.
NTP Default Configuration
Enabling NTP in Broadcast-Client Mode, page 34-3
Configuring NTP in Client Mode, page 34-4
Configuring Authentication in Client Mode, page 34-4
Setting the Time Zone, page 34-5
Enabling the Daylight Saving Time Adjustment, page 34-6
Disabling the Daylight Saving Time Adjustment, page 34-7
Default Value
Disabled
Disabled
3000 microseconds
Not specified
0 hours
Disabled
None specified
Disabled
Chapter 34 Configuring NTP
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