Cisco Cisco 2504 Wireless Controller Guía Para Resolver Problemas

On a WLC, the system date and time can be manually configured from the WLC or configured to obtain the
date and time from an NTP server.

The system date and time can be manually configured using the CLI configuration wizard or the WLC
GUI/CLI. This document provides a configuration example for synchronizing the WLC system date and time
through an NTP server.

NTP is an Internet protocol used to synchronize the clocks of computers to some time reference. RFC 1305

 provides detailed information on NTP v3 implementation. An NTP network usually receives its time from

an authoritative time source, such as a radio clock or an atomic clock attached to a time server. NTP then
distributes this time across the network. An NTP client makes a transaction with its server over the polling
interval (from 64 to 1024 seconds), which dynamically changes over time depending on the network
conditions between the NTP server and the client. The other situation occurs when the router communicates to
a bad NTP server (for example, NTP server with large dispersion). The router also increases the poll interval.
No more than one NTP transaction per minute is needed to synchronize two machines. It is not possible to
adjust the NTP poll interval on a router.

NTP uses the concept of a stratum to describe how many NTP hops away a machine is from an authoritative
time source. For example, a stratum 1 time server has a radio or atomic clock directly attached to it. It then
sends its time to a stratum 2 time server through NTP, and so forth.

For more information on the best practices for NTP deployment, refer to Network Time Protocol: Best
Practices White Paper. The example in this document uses a Cisco 2800 router as an NTP server. The WLC is
configured to synchronize its date and time with this NTP server.

Use this command in global configuration mode if you want the system to be an authoritative NTP server,
even if the system is not synchronized to an outside time source:

ntp master

If you want to authenticate the associations with other systems for security purposes, use the commands that
follow. The first command enables the NTP authentication feature. The second command defines each of the
authentication keys. Each key has a key number, a type, and a value. Currently, the only key type supported is
md5. Third, a list of "trusted" authentication keys is defined. If a key is trusted, this system will be ready to
synchronize to a system that uses this key in its NTP packets. In order to configure NTP authentication, use
these commands in global configuration mode:

ntp authenticate