Wireless LAN Controller Best Practices

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Jun 29th, 2010
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I am having a discussion with a workmate regarding when and how many Wireless LAN controllers are needed when deploying an Enterprise WLAN.  Is there a document or link that shows the best practices on when to deploy and how many Wireless LAN Controllers should be deployed based on the amount of APs, sites, branches etc.


I'm designing a WLAN for an organization that will have a central office and six remote sites within the WAN (bonded T1 connectivity).  We will start out with 25 APs at each site. A Wireless Guest network will be configured so non-employees have the option to authenticate to the WLAN at each site. I have planned for a Wireless LAN Controller at each site to streamline the deployment of AP's now and in the future.  My workmate is arguing that I should just use two Wireless LAN Controllers and position these at the central office and all AP's will be centrally managed by these two controllers.  My thought on this is that if all my sites have their own networks/VLANs.  Also, with the need for Guest access at each site, I would want a Wireless LAN Controller to facilitate this mobility option within each site's LAN.


Is there any documentation that I can consult for best practices on the deployement of Wireless LAN Controllers?


Thanks,


D

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Leo Laohoo Tue, 06/29/2010 - 22:59
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Wireless LAN Controller (WLC) Configuration Best Practices

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a0080810880.shtml


Hope this is what you are looking for.  Please don't forget to rate useful posts.  Thanks.

mprofitt1967 Fri, 09/10/2010 - 17:14
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I would like to have an answer to this qestion as well. I see many customers deploy the WLC at a centralized location but I am not convinced this is the best method. For instance, the 802.11a/n and 802.11b/g/n parameters are global. You can not adjust them for individual locations. This can potentially cause some problems.

Unfortunately the Wireless LAN Controller (WLC) Configuration Best Practices document does not address the question of centralized vs decentralized deployment of controllers.

I would also like to know what the recommendation is when rolling out W-LAN Controllers. Should we put 440x models in each branch or just two 5508 in our Data Center?

Georgios Nikitas Wed, 11/10/2010 - 05:45
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Please keep in mind that ALL traffic from wireless clients is tunneled and sent to the wireless controller.

If your wireless clients need to access resources on the local site, it makes no sense to send all the traffic to your central site and then back to the remote site. This would be a tremendous waste of bandwidth and it would add delay to your applications.

If your wireless clients need to access resources that are located on the central site, then it is no problem I guess. But still you will load your WAN with control traffic between the APs and the WLCs.

So my personal suggestion is to use WLC at each site, unless you have high bandwidth WAN links.

Hi,


I had the same dillema i.e where to deploy WLC for a corporate having multiple sites.


What I can tell you consider the following:


If most of the traffic should be kept local to the site you can use H-REAP mode though if you have more than 3 APs per site (and most probably you have) then it is not recommended/supported by Cisco.

So if your wireless traffic is mostly towards applications hosted at for instance in a DC then you can go ahead with centralized WLC assuming you have sufficient WAN bandwidth.

If your wifi traffic mostly toward local file servers for instance better to use H-REAP (less than 3 APs per site) or use local WLC.

Another thing is I was told that AP to WLC control traffic consumes roughly 128kbps per AP. I don't know if it is correct but better to calculate with.

So be carefull with centralized deployment.


So I would say your design fits the requirements and also inline with recommendations. The gues traffic can be tunneled back to the central controller if you have centralized Internet breakout (auto-anchor).

You may take a look to this link:

http://www.cisco.com/en/US/prod/collateral/wireless/ps5679/ps5861/prod_white_paper0900aecd804f1a23_ns337_Networking_Solutions_White_Paper.html


Hope this help rate if does,


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