Implementing NTP on Cisco IOS XR Software
How to Implement NTP on Cisco IOS XR Software
The communications between 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 associations. Accurate timekeeping is made possible by exchanging NTP messages between each pair of machines with an association.
However, in a LAN environment, NTP can be configured to use IP broadcast messages instead. This alternative reduces configuration complexity, because each machine can simply be configured to send or receive broadcast messages. However, the accuracy of timekeeping is marginally reduced because the information flow is
The time kept on a machine is a critical resource, so we strongly recommend that you use the security features of NTP to avoid the accidental or malicious setting of incorrect time. Two mechanisms are available: an access
When multiple sources of time (VINES, hardware clock, manual configuration) are available, NTP is always considered to be more authoritative. NTP time overrides the time set by any other method.
How to Implement NTP on Cisco IOS XR Software
This section contains the following procedures:
•“Configuring
•“Configuring
•“Configuring NTP Access Groups” section on page
•“Configuring NTP Authentication” section on page
•“Disabling NTP Services on a Specific Interface” section on page
•“Configuring the Source IP Address for NTP Packets” section on page
•“Configuring the System as an Authoritative NTP Server” section on page
•“Updating the Hardware Clock” section on page
•“Verifying the Status of the External Reference Clock” section on page
Configuring Poll-Based Associations
This task explains how to configure
Note No specific command enables NTP; the first NTP configuration command that you issue enables NTP.
Poll-Based Associations
Networking devices running NTP can be configured to operate in variety of association modes when synchronizing time with reference time sources. There are two ways that a networking device can obtain time information on a network: by polling host servers and by listening to NTP broadcasts. In this task, we will focus on the
Cisco IOS XR System Management Configuration Guide
