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New Member

WLC Redundancy

Hi,

I will be deploying 2 units of WLC4402, which run as active-passive (all the LAP will be registered to the primary WLC, the secondary WLC will only come up when the primary WLC fails).

Since I will be creating multiple VLAN to be associated to the WLAN(SSID) on both WLC,

1) May I know the VLAN IP address of the 2 WLC are the same or it must be different?

ANd we plan to have the LAP and WLC to be in the same subnet, does that means I will be running on Layer 2?

2) and if this is the case, I do not need DHCP option 45, right?

I'm new to the Unified wireless, and I can't seems to find the answer anywhere..or maybe I'm in the wrong URL..

Thanks in advance.

18 REPLIES

Re: WLC Redundancy

Hi there,

i have reciently set this up for a client and used the floowing great document.

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_configuration_example09186a008064a294.shtml

If you re looking to redundancy then make sure that you have both controlers in the same mobility group and configure each WLC with the others MAC address under the Mobility group section. Controller>> Mobility management> Mobility Groups (4.1.171.0 software)

Also configure the primary and secondary controllers on all AP's (make sure that you you use the controller's system name and not ip address)

also make sure that you have the same WLAN and security configured on each controller.

In answer to you specific questions the ap addresses on the interfaces on the controllers must be different but should be in the same VLAN

No you do not need option 45? (43!) but i would always use it hwere possible.

Best things is give the docement a good read, if you have any more questions, post back

Hope this has helped,

Mark

*Pls rate all useful posts

New Member

Re: WLC Redundancy

sorry my typo error, it dhcp option 43...

but i do not have any dns server, can i stil use the system name instead of the ip address?

Re: WLC Redundancy

Yes DOT NOT USE an ip address in that field. It is not using DNS with the system name.

I use the WCS software when configuring more than one WLC, that way you can creat templates and then push them to the controller, makes it a lot more easier!!

Cheers

Mark

*Pls rate all useful posts

New Member

Re: WLC Redundancy

but if i do not have a DNS server, can i still use the system name??

do the LAP know how to resolve the WLC name to an IP address if there are no dns server?

New Member

Re: WLC Redundancy

anybody can reply naive.naive's messege. I also having the same scenario, we do have two controllers with out DNS server inside the network, how we can configure failover by giving only the name?

Thanks

Cisco Employee

Re: WLC Redundancy

Hi Rajesh/Naive,

You have to configure controller system name in primary and secondary controller option for all APs. It is not related to dns. When AP boots up controller exchange some control messages with AP and it updates it system name.

So once you configure primary and secondary controller system name it gets updated in AP and when primary controller is not available AP discovers secondary controller because it keep exchanging those messages.

HTH

Ankur

*Pls rate all helpfull post

New Member

Re: WLC Redundancy

Ankur,

I had tried the same, we given controller name in the AP list, and i tried to switch of the primary controller but ap didnt get register to the second controller. pls note that i hve given static IPs to the APs and both the controller are in different subnet. kindly refer the attached images for more information

thanks in advance

Raj

Re: WLC Redundancy

Assignment of Primary, secondary, and tertiary controllers to the APs does not guarantee that you will reassociate to those controllers. There are a lot of factors involved with failover. Please see the attached documentation. Attached is a configuration example and a couple of slides that depict the LWAPP discovery process as a flow chart.

New Member

Re: WLC Redundancy

Thanks for the prompt response.

We followed the same pdf only; i few questions on that.

1 as i mentioned before, for finding the second controller in the discovery process, is that necessory to have a dns in the local network to resolve the sysname?

2 if there is no DNS then how the AP able to resolve the IP of a secondary controller which is residing in a different subnet?

3 We have configured static IPs insted of option 43, will it make any difference.

4 Can u suggest any command which can able to diagonose this case?

Thanks for helping me

Raj

Re: WLC Redundancy

1. DNS entry is required to be available on the local network.

2. It couldn't resolve the name due to there being no DNS server to handle the resolution of host name to ip address.

3. Static IPs can cause problems with duplicate address issues as well as being more vulnerable to DOS attacks.

4. Do an LWAPP debug all and follow the process to see where it fails.

New Member

Re: WLC Redundancy

thanks dennis. Do you have any command which i can add secondary controller as i did for primary controller (lwapp controller ip address ) ?

Thanks

raj

Re: WLC Redundancy

Under the configuration for each AP is a box for the sysyem name of the Primary, Secondary, and Tertiary controllers. Simply fill in these boxes and failover will do its best.

New Member

Re: WLC Redundancy

thanks dennis. Do you have any command which i can add secondary controller as i did for primary controller (lwapp controller ip address ) ?

Thanks

raj

Cisco Employee

Re: WLC Redundancy

Hi Raj,

First thing no DNS resolution is required when you configure primary,secondary and tertiary controller for each ap.

Now the command is

config ap primary-base

config ap secondary-base

config ap tertiary-base

Failover will only happen when you configure mobility group properly and if primary controller in not reachable then it will fall back to secondary controller.

If this is not working for you can you paste me the output of "sh mobility summary"?

HTH

Ankur

*Pls rate all helpfull post

New Member

Re: WLC Redundancy

Thanks Ankur, Please find the command out put what you have requested.

Controller 1:

(WLC-ITC1) >show mobility summary

Symmetric Mobility Tunneling (current) .......... Disabled

Symmetric Mobility Tunneling (after reboot) ..... Disabled

Mobility Protocol Port........................... 16666

Mobility Security Mode........................... Disabled

Default Mobility Domain.......................... ITCMOBGROUP

Mobility Keepalive interval...................... 10

Mobility Keepalive count......................... 3

Mobility Group members configured................ 2

Controllers configured in the Mobility Group

MAC Address IP Address Group Name Status

00:18:ba:49:75:60 10.17.211.15 ITCMOBGROUP Up

00:18:ba:49:77:a0 10.17.209.15 Up

Controller 2:

Symmetric Mobility Tunneling (current) .......... Disabled

Symmetric Mobility Tunneling (after reboot) ..... Disabled

Mobility Protocol Port........................... 16666

Mobility Security Mode........................... Disabled

Default Mobility Domain.......................... ITCMOBGROUP

Mobility Keepalive interval...................... 10

Mobility Keepalive count......................... 3

Mobility Group members configured................ 2

Controllers configured in the Mobility Group

MAC Address IP Address Group Name Status

00:18:ba:49:75:60 10.17.211.15 Up

00:18:ba:49:77:a0 10.17.209.15 ITCMOBGROUP Up

Could you please confirm the configuration is correct or not?

thanks

raj

Cisco Employee

Re: WLC Redundancy

Hi Raj,

Your config and output makes me believe your mobility should work fine. Is your AP fallback not working?

Regards,

Ankur

Re: WLC Redundancy

Initial discovery of a controller is required for an AP to associate to a controller. After that, the AP learns the location of controllers within the mobility group. Maybe I was a little confusing there.

New Member

Re: WLC Redundancy

Thanks Dennis and Ankur... after restarting all the APs once again, it worked. i tested both the way, its working fine. Thank you for helping me.

regards

raj

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