Wireless Access

Hi guys,

I have a building with 5 floors and my Wi-Fi design threw me around 100 IAPs. Now I have to make the cluster design.
I know I can support this with a single cluster since my design has less than 128 APs and 2048 users, but wouldn't be better to have two clusters of 50 IAPs each in such a way that each cluster is less loaded of APs and users?
On the other hand, my building won't have coverage in the elevator and stairs between floors, so roaming between floors won't be practical. In this case, is useful to have a single cluster per floor or not? I have read the Instant VRD and it says the recommendation is to have a single cluster if you have less than 128 APs. But it also says in the case of several buildings in a non-continuous RF domain, support each building with a single cluster. I have a mix of both cases. With all of this in mind, what are your recommendations? Thanks for your help.

Regards,
Julián

What is the AP coverage between floors? You mentioned no coverage in the stairs or elevators, but if it's still possible for a client on one floor to hear an AP on the floor above/below, then you'll want to take that into account as well.

 

Alongside that, what are the applications that need to be supported over the wireless network? If a hard roam (full re-authentication) takes place when moving from an AP on the same floor to an AP on another floor, does that impact the user experience? 

 

Maybe most importantly, what do you think will be an easier deployment to manage and support for the customer? Will they have Airwave to monitor/manage the configuration across multiple clusters? When troubleshooting issues, will they effectively be able to track where a user is currently connected and how they move/roam through the environment?

Hi Charlie,

 

Wow, how many things to take into consideration. I thought the decision would be much simpler.

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@cclemmer wrote:

What is the AP coverage between floors? You mentioned no coverage in the stairs or elevators, but if it's still possible for a client on one floor to hear an AP on the floor above/below, then you'll want to take that into account as well.

 

Alongside that, what are the applications that need to be supported over the wireless network? If a hard roam (full re-authentication) takes place when moving from an AP on the same floor to an AP on another floor, does that impact the user experience?

 

Users will not use critical applications or voice over Wi-Fi, so I think a hard roam is not a problem. But how does this influence in the cluster design? In any case, I can configure more than a cluster and enable L3 roaming between them. 

 

Maybe most importantly, what do you think will be an easier deployment to manage and support for the customer? Will they have Airwave to monitor/manage the configuration across multiple clusters?

 

At the moment they have AirWave, but if they want to change, Aruba Central can also manage different clusters, right?

 

When troubleshooting issues, will they effectively be able to track where a user is currently connected and how they move/roam through the environment?

 

Do you mean is easier to track a user within a big single cluster or within one of some smaller clusters?

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Regards,

Julián

 

Long story short, an Instant Cluster of 100 access points will be fine.  You just need to make sure that there is very little broadcast traffic on the management VLAN of the Instant AP.

 

You don't want users roaming every time they are on different floors and it will be harder to troubleshoot and manage users with multiple clusters.

 

Central can manage multiple clusters, but you don't want to do that in this circumstance because management will be harder across clusters.

 

Also, users can be on one floor but roam to a different floor, which means your cluster roams can be significant.

OK Colin, it makes a lot of sense. Thanks for your recommendations.

 

Regards,

Julián

Colin pretty well spelled out where I was leading you, but here are the answers to your specific questions:

 

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@fjulianom

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@cclemmer Users will not use critical applications or voice over Wi-Fi, so I think a hard roam is not a problem. But how does this influence in the cluster design? In any case, I can configure more than a cluster and enable L3 roaming between them. 

  

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Why add the additional complexity with L3 roaming if a single large cluster would handle the scale needed?

 

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At the moment they have AirWave, but if they want to change, Aruba Central can also manage different clusters, right?  

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That's correct, Airwave and Central can both manage different clusters. 

 

Do you mean is easier to track a user within a big single cluster or within one of some smaller clusters?

What types of problems typically need debugging? Usually roaming, since stationary devices tend to behave fairly static. If a device is also roaming between clusters, now there are different management points to check in order to get a clear view of the client behavior. 

 

My response was intended to stir the thought that a cluster deployed on a single floor may not be restricted to just that floor. If a client device can see APs on neighboring floors, it may well decide to try to roam to one of those APs. So the decision to break a cluster into multiple smaller clusters should consider the benefits vs the added complexity. There not necessarily a right or wrong answer to the question, it comes down to the requirements and what the customer can handle when it comes to daily operations and management.

 

I've over-engineered solutions for customers and needed to go back to simplify the design to better fit their operations. Trying to save others the same. ;)

Hi Charlie,

 

Very well explained :) Many thanks for your time.

 

Regards,

Julián