Wireless Access

Hi gurus,

 

I have three sites geographically separated and L3 connected, each one with one controller. I know I can have site1's APs pointing to site1's controller, and if this controller fails, the APs can fail over to the site2's controller, as indicated with the backup-LMS in the AP system profile.

 

Now, is possible to have site1's APs pointing to site1's controller as the primary controller, site2's controller as secondary controller is site1's controller fails, and site3's as tertiary controller if site1 and site2's controllers fail? Many thanks in advance.

 

Regards,

Julián

Unfortunately, there is no way to do this.

 

 

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@cjoseph wrote:

Unfortunately, there is no way to do this.

 

 

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Hi Colin,

 

I forgot to say, but I will also have a MM for managing the three controllers. I guess it is not possible either with a MM. Can you confirm?

 

Regards,

Julián

It is not possible with an MM.

 

Controllers do not fail often (the only moving part is typically a fan in the power supply).  If you need high availability at a site because you need wireless 24/7 put a second controller there.   Failing over to a second site is very disruptive, because all devices will have to request a different ip address (if the device even detects the failover).  This is not to mention the slowness of the WAN between sites that would make wireless painful.

Sure, I agree. But my customer has limited budget and a second controller at the site will be in a second phase. But in the meantime and in the case of a controller failure is better to have a regular wireless service for a while than not wireless at all.

Regards,
Julián

Well, the customer will be satisfied with Backup LMS, because controllers do not fail often.  

Hi Collin,

Just the last thing about this. In this case, is better to have a single three-member L3 cluster, or three one-member clusters? What are the pros and cons of each case?

Regards,
Julián

A cluster is two or more controllers at a physical site that are fully redundant.

 

There is no one member cluster.

 

 

Hi,

 

Yes, that's right, I might haven't expressed well. The question is:

 

In my scenario is better to have a cluster of three controllers (L3), or three controllers managed by the MM without forming a cluster? What are the pros and cons of each case?

 

I read a post (which I can't found now) stating that in some cases is better to have independent controllers managed by the MM instead of creating a cluster.

 

Regards,

Julián

Hi fjulianom,

 

Reading through your posts and trying to understand the topology I would not recommend a cluster setup between sites. 

 

You will only benefit from the cluster if all members are L2 connected. If they are on different sites, which are L3 connected you will lose most of the benefits of the cluster, like fast failover and so one. 

Another point against the cluster across sites might be, that AP's and clients are balanced across all members. This means, that AP's and clients from one site might be connected to a controller on a different site. From my point of view, this is not what you want and something I would never recommend. 

 

If you will have only one controller per site, you should run them as a single controller managed by the MM. As already said, controller failing is very uncommon. 

 

If you start phase two of the project and you get a second controller per site, I would create a two-node cluster per site. And even with this setup, you can let the AP's failover to a cluster on a different site, for the case even the two controllers on the same site fail, at the same time. 

 

hope this makes sense to you. 

 

BR

Florian

Hi Florian,

 

And it makes a lot of sense! Great explanation! Many thanks :)

 

Regards,

Julián