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Rajan Parmar
Cisco Employee
Cisco Employee

# HA can be configured between two WLCs, if the conditions as documented at
http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.html#pgfId-44069 , are met.

#
As per http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.html#pgfId-43357 -> Step 1,

"Before you configure HA, it is mandatory to have both the controllers' management interface in the same subnet"


#

There will be four ip addresses involved to setup HA between two WLCs:

-First two will be the ip addresses given to the management interface of both WLCs.

-Other two will the ip addresses given to the redundancy-management interface of both WLCs.

After giving, say, IP3 and IP4 to the Management interface of WLC1 and WLC2:

-if

we assign IP1 to the Redundancy Management IP Address for WLC 1.

we assign IP2 to the Redundancy Management IP Address for WLC 2.

-then

need to give IP2 to the Peer Redundancy Management IP Address for WLC 1.
need to give IP1 to the Peer Redundancy Management IP Address for WLC 2.

(these redundancy ip addresses are ONLY used by the WLCs to exchange keep-alives)

#

The ip address in the following two fields are kept same:
Controller ->Redundancy  ->Redundancy Mgmt Ip
Controller- > Interfaces- >redundancy-management

#


The prerequisite for a 5508 unit to be configured as Stand-by WLC:
either we need at least 50 licenses
or the unit must be HA-SKU enabled

#


As per http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.html#pgfId-43357 -> Step 4, before we enable SSO (Redundancy), need to ensure the following:

-Both the WLCs are connected, from an Ethernet cable, via Redundant Ports of the two WLCs.
-The gateway of the network (of the two WLCs) must be reachable from both the WLCs.
(So, if we can login to the GUI/CLI of the two controllers, will indicate that the WLCs are reachable to their common gateway also)


#
As per www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.html#pgfId-43357 -> Step 5, we can enable AP-SSO.

{Once SSO is enabled:
-The Standby WLC can be accessed via console connection or via SSH on the service port
-Both WLCs will reboot.
-During the reboot, the WLCs negotiate the HA role (via Redundant Port)
If the WLCs cannot reach each other via the Redundant Port, the WLC (configured as Secondary) may go in Maintenance Mode.
For reference, you might want to check at
www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.html#pgfId-43357 -> Step 6,7,8 }

#
To verify if SSO (Redundancy) is working fine:
Can visit www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.html#pgfId-43357 -> Step 8

# Whenever you have to upgrade the WLCs, just need to upgrade the Active WLC, it will take care of the backup WLC also.
We can setup a console session to Secondary WLC and check of the upgrade process.

 

In the discussion below, we will assume that:
Primary   WLC is the one that we have configured to be Primary   in the HA configuration.
whose output of 'show redundancy summary' will say Local State = Active, Peer State : Standby Hot.

Secondary WLC is the one that we have configured to be Secondary in the HA configuration.
whose output of 'show redundancy summary' will say Local State = Standby Hot, Peer State : Active.
------------------------------------------------------------------------------------------------
Its a known fact that a Primary WLC has to be AIR-CT5508-A-K9 with at least one AP license.
The Secondary WLC has to be either AIR-CT5508-HA-K9 ( ha-sku enabled ) or AIR-CT5508-A-K9 with 50 licenses.
------------------------------------------------------------------------------------------------
HA-sku units  can work as standalone(without HA)
HA-sku units !can work as Primary   (in      HA)
HA-sku units  can work as Secondary (in      HA) , as then they inherit the licenses from the Active WLC.


Just in case, Active fails, the Stand-by( which can be HA sku unit) becomes the fail-over device to support the APs and clients

Becuase,
 the purpose of HA SKU unit is only to inherit licenses.
Hence,
 - we can't even install the licenses on the HA-SKU units , becuase, The purpose of HA SKU unit is only to inherit licenses.
 - In other words, if you will configure a WLC to be as a HA SKU unit, will indicate that you don't want the unit to manually inherit license.
So , you shouldn't even try to install licenses on it, manually.
 - In , yet, other words, if you are trying to install licenses on a WLC, it shouldn't be an HA SKU unit (if it is, then it should HA-SKU functionality should be disabled)
------------------------------------------------------------------------------------
[?]Now, how to check if a given unit is HA-SKU or not ?
[=]For this, you can go through the following two examples:

Example1:
--------
Say, if we are in the console session of the WLC that we have configured as the Secondary WLC in HA configuartion:
- if we get 0 as the output for the following two commands, will indicate that the unit is not ha-sku capable, so it should have been configured as Primary WLC in HA
(Cisco Controller) >devshell getHaSkuAbility
value = 0 = 0x0
(Cisco Controller) >devshell isItHaSkuController
value = 0 = 0x0

- if we get 1 as the output for the following two commands, will indicate that the unit is ha-sku capable, so it is good to be used as a Secondary WLC.

(Cisco Controller) >devshell getHaSkuAbility
value = 1 = 0x1
(Cisco Controller) >devshell isItHaSkuController
value = 1 = 0x1


Example2:
--------
Say, if we are in the console session of the WLC that we have configured as the Primary WLC in HA configuartion:
- if we get 0 as the output for the following two commands, will indicate that the unit is not ha-sku capable, so it good to be used as Primary WLC in HA
(Cisco Controller) >devshell getHaSkuAbility
value = 0 = 0x0
(Cisco Controller) >devshell isItHaSkuController
value = 0 = 0x0

- if we get 1 as the output for the following two commands, will indicate that the unit is ha-sku capable, so it should have been configured as Secondary WLC in HA
(Cisco Controller) >devshell getHaSkuAbility
value = 1 = 0x1
(Cisco Controller) >devshell isItHaSkuController
value = 1 = 0x1
------------------------------------------------------------------------------------

Comments
Muhammed Adnan
Level 4
Level 4

Hi Rajan,

An helpful post, thanks.

I have a WLC with 0 licenses, which I would want to configure as HA standby. I am planning to activate the evaluation licenses and then configure it as standby. 

After successful HA configuration, the licenses on primary will any how be derived on the standby. 

Please suggest if this solution will address my concern.

 

Thanks,

Adnan

Rajan Parmar
Cisco Employee
Cisco Employee

Hi Adnan,

In an ha sku unit of WLC, we don't need to install licenses as they inherit from the active WLC in HA setup.

In a non-ha sku unit of WLC, we do need to install licenses (minimum of 50 AP)

Thanks.

Mahmoud
Level 1
Level 1

thanks for the post

I have two standalone  WLC 5508 with base license of 50 APs so I need to cluster but over L2 switch. wht configuration should be done in switch and do we have special configuration for that at WLC

David Vaquerano
Level 1
Level 1

Great article Rajan,

I have a question that I think you can help me with. 

What if I have two HA-SKU controllers and I want to use them together as an SSO pair of anchor controllers for guest wireless? I dont need any APs to be able to associate to this controllers.

Is this something possible to do? If so, do I need to worry about licensing and failover inherit licenses?

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