This document explains how to configure wireless LAN controllers (WLCs)
for synchronizing the date and time with a Network Time Protocol (NTP)
Ensure that you meet these requirements before you attempt this
The information in this document is based on these software and
The information in this document is based on these software and
The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.
Technical Tips Conventions for more information on document
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.
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
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.
Configuring the Router as an Authoritative NTP
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:
!--- Makes the system an authoritative NTP server
Configuring NTP Authentication
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:
!--- Enables the NTP authentication feature
ntp authentication-key number md5 value
!--- Defines the authentication keys
ntp trusted-key key-number
!--- Defines trusted authentication keys
Here is an example NTP Server configuration on the 2800 Series Router.
The router is the NTP master, which means the router acts as the authoritative
ntp authentication-key 1 md5 0305480F0008 7
ntp trusted-key 1
Starting with the 220.127.116.11 release, you can also configure an
authentication channel between the controller and the NTP server. In order to
configure NTP authentication using the controller GUI, perform these steps:
Choose Controller > NTP > Servers to open the
NTP Servers page. Click New to add an NTP server.
The NTP Servers > New page
Choose a server priority from the Server Index
(Priority) drop-down list.
Enter the NTP server IP Address in the Server
IPAddress text box.
Enable NTP server authentication by selecting the NTP Server
Authentication check box.
Choose Controller > NTP >
Click New to create a key.
Enter the key index in the Key Index text
Choose the key format from the Key Format drop-down
Enter the Key in the Key text
You can use these commands from the WLC CLI to verify the
(Cisco Controller) >show time
Time............................................. Wed Nov 23 15:31:27 2011
Timezone delta................................... 0:0
Timezone location................................ (GMT -6:00) Central Time (US and Canada)
NTP Polling Interval......................... 86400
Index NTP Key Index NTP Server NTP Msg Auth Status
1 1 10.78.177.30 AUTH SUCCESS
You can use the debug ntp detail enable
command to view the sequence of events that occur once the NTP server
configuration is done on the WLC.
*sntpReceiveTask: Nov 23 15:08:24.360: Started=3531049704.360568 2011 Nov 23 15:08:24.360
*sntpReceiveTask: Nov 23 15:08:24.360: Looking for the socket addresses
*sntpReceiveTask: Nov 23 15:08:24.360: NTP Polling cycle: accepts=0, count=5, attempts=1, retriesPerHost=6.
Outgoing packet on NTP Server on socket 0:
*sntpReceiveTask: Nov 23 15:08:24.360: sta=0 ver=3 mod=3 str=15 pol=8 dis=0.000000 ref=0.000000
*sntpReceiveTask: Nov 23 15:08:24.361: ori=0.000000 rec=0.000000
*sntpReceiveTask: Nov 23 15:08:24.361: tra=3531049704.360889 cur=3531049704.360889
*sntpReceiveTask: Nov 23 15:08:24.361: Host Supports NTP authentication with Key Id = 1
*sntpReceiveTask: Nov 23 15:08:24.361: NTP Auth Key Id = 1 Key Length = 5
*sntpReceiveTask: Nov 23 15:08:24.361: MD5 Hash and Key Id added in NTP Tx packet
*sntpReceiveTask: Nov 23 15:08:24.361: Flushing outstanding packets
*sntpReceiveTask: Nov 23 15:08:24.361: Flushed 0 packets totalling 0 bytes
*sntpReceiveTask: Nov 23 15:08:24.361: Packet of length 68 sent to 10.78.177.30 UDPport=123
*sntpReceiveTask: Nov 23 15:08:24.363: Packet of length 68 received from 10.78.177.30 UDPport=123
*sntpReceiveTask: Nov 23 15:08:24.363: KeyId In Recieved NTP Packet 1
*sntpReceiveTask: Nov 23 15:08:24.363: KeyId 1 found in recieved NTP packet exists as part of the trusted Key/s
*sntpReceiveTask: Nov 23 15:08:24.363: The NTP trusted Key Id 1 length = 5
*sntpReceiveTask: Nov 23 15:08:24.363: NTP Message Authentication - SUCCESS
*sntpReceiveTask: Nov 23 15:08:24.363: sta=0 ver=3 mod=4 str=8 pol=8 dis=3.875031 ref=3531071269.384065
*sntpReceiveTask: Nov 23 15:08:24.363: ori=3531049704.360889 rec=3531071270.103183
*sntpReceiveTask: Nov 23 15:08:24.363: tra=3531071270.103387 cur=3531049704.363251