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Controller and APs through MPLS

Hi experts,

 

I have to implement a network for three sites. The sites are separated geographically and connnected through a MPLS network. The network would consist of a master controller in the main site, and three local controllers, one per-site. Let's say:

 

Site A: Master controller and local controller.

Site B: Local controller.

Site C: Local controller.

 

Customer has no money for the three local controllers, so for one site there are two options. One, to have a cluster of IAPs, or two, connect the APs of this site to the local controller of other site (for example, connect the APs of site C to the local controller of Site B).

 

For site A and site B there is no problem since the local controller and APs would be in the same site connected through a switched network. But for site C, is there any inconvenient for the second option? I mean, would be any problem or the performance would be lower taking into account the controller and the APs wouldn't be connected directly but through a MPLS network?

 

Regards,

Julián

Aruba Employee

Re: Controller and APs through MPLS

For wireless users at these three sites, were are the resources they would be accessing located? Do they have local file/print services, or is the traffic headed to the cloud or a remote data center?


Charlie Clemmer
Aruba Customer Engineering

Re: Controller and APs through MPLS

Hi Charlie,

 

Well, they are three campus of a university, so the students use wireless for browsing the Internet as well as for local printing or local resources for lab. So I understand for this use it is better to have a local controller in each campus/site, isn't it?

 

Regards,

Julián

Aruba Employee

Re: Controller and APs through MPLS


@fjulianom wrote:

Hi Charlie,

 

Well, they are three campus of a university, so the students use wireless for browsing the Internet as well as for local printing or local resources for lab. So I understand for this use it is better to have a local controller in each campus/site, isn't it?

 

Regards,

Julián


I would agree with you. For a university environment, you would not want to have client traffic tunneled to another campus just to terminate on a controller. If having a local controller at each campus is not feasible, then I suggest investigating whether Instant would be a suitable option for the smaller campus.


Charlie Clemmer
Aruba Customer Engineering

Re: Controller and APs through MPLS

Hi Charlie,

 

It makes a lot of sense, many thanks!

 

Regards,

Julián

Re: Controller and APs through MPLS

Hi Charlie,

Please two more doubts about this:

1. If site C were connected to site B's controller, would all the traffic go first to the controller through the tunnel (including ARPs, DHCP requests, etc.)?

2. Would the roaming be affected in some way as the clients are in one site and the roaming decisions would be in other site. I don't know if the MPLS delay between sites would affect the roaming performance.

Regards,
Julián

Aruba Employee

Re: Controller and APs through MPLS


@fjulianom wrote:


1. If site C were connected to site B's controller, would all the traffic go first to the controller through the tunnel (including ARPs, DHCP requests, etc.)?


Yes, that is correct. If there is no controller at site C, their APs should tunnel to where the majority of their traffic needs to flow anyway. If they have mostly local resources (local printers, file servers, etc), then an Instant cluster at site C may be more beneficial.

 


@fjulianom wrote:


2. Would the roaming be affected in some way as the clients are in one site and the roaming decisions would be in other site. I don't know if the MPLS delay between sites would affect the roaming performance.


Roaming is determined by the client device. Authentication takes place at the controller, so depending on the overall latency, may or may not be an issue. With the MPLS link, the round trip time should still be less than 150ms to suitable performance.


Charlie Clemmer
Aruba Customer Engineering

Re: Controller and APs through MPLS

Hi Charlie,

For the second point, I know that roaming is triggered by the client, though we can try to influence roaming by enabling ClientMatch. In any case I would like to know if the roaming would be affected in some way since the physical roaming is taking place in site C and ClientMatch calculations take place at site B, and for example the client's information is passed from the controller to the new AP, and all this with a MPLS link between them. Then, could I consider to have a maximum delay of 150 ms between the sites? I know to have a cluster of IAPs is much better and is my proposal to customer, I am asking for curiosity and also to have solid arguments to talk about with my customer.

Regards,
Julián
Aruba Employee

Re: Controller and APs through MPLS

With acceptable latency between the two sites, there should not be any negative effects on roaming. Client match acts on what the local APs hear in the air, which is the same regardless of where the controller is connected.

Charlie Clemmer
Aruba Customer Engineering
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