Basic Ntp Configuration - Cisco ASR 5500 Installation Manual
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- System administration manual (430 pages) ,
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- Installation manual (192 pages)
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▀ Set System Timing
The system should have:
NTP enabled.
NTP configured for use in the local context only. Use of other contexts (which can be specified in the enable
configurable) will cause issues.
NTP configured for three external NTP servers. With three or more servers, outlyers and broken or
misconfigured servers can be detected and excluded. Generally, the more servers the better (within reason).
Important:
algorithms already have the built-in ability to pick the best server. Use of prefer usually results in a poorer choice than
NTP can determine for itself.
Important:
Cisco TAC.
Basic NTP Configuration
Important:
simplifies the time zone shift that must be corrected by the NTP server. See
Use the following example to configure the necessary NTP association parameters:
[local]host_name# config
[local]host_name(config)# ntp
[local]host_name(config-ntp)# enable
[local]host_name(config-ntp)# server <ip_address1>
[local]host_name(config-ntp)# server <ip_address2>
[local]host_name(config-ntp)# server <ip_address3>
[local]host_name(config-ntp)# end
[local]host_name#
By default <context_name> is set to local. This is the recommended configuration.
A number of options exist for the ntp server command. Refer to the NTP Configuration Mode Commands chapter in
the Command Line Interface Reference for more information.
Important:
Save the configuration as described in
Configuring NTP Servers with Local Sources
NTP can use network peers, local external clocks (such as GPS devices), or a local clock with no external source.
A local clock with no external source is usually a last-resort clock when no better clock is available. It is typically
configured on a site's intermediate NTP server so that when a WAN network outage occurs, hosts within the site can
continue to synchronize amongst themselves.
▄ ASR 5500 Installation Guide
118
Do not configure any external NTP servers using the prefer keyword. The NTP clock selection
Do not change the maxpoll, minpoll, or version keyword settings unless instructed to do so by
Configure the system clock and time zone prior to implementing NTP support. This greatly
Configure the system with at least three (preferably four) NTP servers.
Save the Basic Configuration.
Initial System Configuration
Setting the System Clock and Time Zone.
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