Cisco ASR 5500 Installation Guide

•
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).
Do not configure any external NTP servers using the prefer keyword. The NTP clock selection 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
Do not change the maxpoll, minpoll, or version keyword settings unless instructed to do so by Cisco
TAC.
Important
Basic NTP Configuration
Configure the system clock and time zone prior to implementing NTP support. This greatly simplifies the
time zone shift that must be corrected by the NTP server. See Setting the System Clock and Time Zone,
on page 109.
Important
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.
Configure the system with at least three (preferably four) NTP servers.Important
Save the configuration as described in Save the Basic Configuration, on page 112.
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.
ASR 5500 Installation Guide
110
Initial System Configuration
Configuring Network Time Protocol Support

Cisco ASR 5500 Specifications

General

Brand	Cisco
Model	ASR 5500
Category	Network Router
Language	English