Redundancy with dual WLC

Answered Question
Jul 28th, 2008
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Hi, I will implement a WLAN network with AP1130AG and WLC 2125. If I understand right the whole traffic to/from the APs (data + management) will be first encapsulated in a LWAPP tunnel to/from the WLC ? Then, the WLC will forward the different traffic VLANs via a 802.1Q trunk to the network. Is it correct ? If so, the WLC is a true single point of failure ! What will happen if the WLC get out-of-service ? What is the impact on existing client sessions and new ones ? How will a redundant WLC 2125 work with the primary (active/standby with HSRP, load balancing)? What are the best practices in such a network ?


Thanks

Correct Answer by Rob Huffman about 8 years 10 months ago

Hi Jean-Pascal,


That is correct, no LWAPP connection (no traffic). A client session will not survive the re-registration due to a WLC Failover :(


Hope this helps!

Rob

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Rob Huffman Mon, 07/28/2008 - 08:21
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Hi Jean-Pascal,


In the WLC world this is how an AP is covered in case one WLC fails. It is not without some "downtime" in case of failure but both Controllers are active. You have to keep in mind that an AP can only be registered to one WLC at a time so this is the best that you can do :) When one WLC fails the AP then has to re-register with the backup, this is not a completly seemless process.



This has some really good info;


WLAN Controller Failover for Lightweight Access Points Configuration Example


http://www.cisco.com/en/US/tech/tk722/tk809/technologies_configuration_example09186a008064a294.shtml#c4


Hope this helps!

Rob


adminccie Tue, 07/29/2008 - 01:04
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Hi Rob,

Thanks for these infos. So, without LWAPP connection between AP and WLC no trafic can occure, right ? Can a client session survive if the primary WLC fails and the AP registers on the backup WLC ?


Thanks



Correct Answer
Rob Huffman Tue, 07/29/2008 - 04:40
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Hi Jean-Pascal,


That is correct, no LWAPP connection (no traffic). A client session will not survive the re-registration due to a WLC Failover :(


Hope this helps!

Rob

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