Controllerless Networks

Hi everybody,

We have a customer who'd like to have more than one cluster in the same layer 2. He works with IAP. Is this possible, and if it is, how ?

Thanks by advance,

Nicolas

Thanks for your response.

I have my answer but not the solution of my problem.

I'm now looking up the standalone mode. Is it possible to enable rf management and roaming for IAPs in standalone mode ? 

Is there a functional reason why would the user want to have individual clusters in the same VLAN?

Yes, there is a big amount of APs at different places. They're linked with a link of layer 2.  

We think that if we put all this APs into one cluster, we'll experience performance issues.

That's why we're trying to do individual clusters. We could create many vlans but the customer doesn't want this solution. 

The standalone solution seems good for places with just 1 AP. But if we can't activate the RF management and the roaming, the solution won't work for places with 2 or more APs...

How many devices are in the single VLAN?  It might not matter.

Yes, there is a big amount of APs at different places.

• How many exactly?  The recommended maximum is 128 APs.  There are many clusters out there of this size.

We think that if we put all this APs into one cluster, we'll experience performance issues.

• Based on what?
• What model of APs are you going to install and (roughly) how many users?

Well I was not really clear. 

We have one Vlan by country. In a country we have about 20 to 30 locations (stores) with 1-3 APs each and the VLAN is shared by all the users or devices of theses stores. Each place is linked to the central through a VPN. In The stores don't have a strong internet connection and we're afraid for the bandwidth. Therefore we'd like to avoid to send unuseful information to the central headquarters, in order to save this bandwidth. We don’t want a part of the bandwidth to be used by the IAPs while they are “discussing” with the virtual controller.

We are using AP-103, and there will be about 5 users per AP.

When you say, "Each place is linked to the central through a VPN", can you elaborate please?

Are you talking about "Aruba Central"? 

No i meant to the headquarters.

I guess we can't enable the rf management nor the roaming in the standalone mode.

Is it possible to simulate a standalone mode by shutting down the ports which create the cluster and by keeping up those who are linked with the rf and the roaming ?

Network diagrams help in understanding topology and concern. So if a L2 VLAN is extending a VPN link, you are worried about inter IAP communication, saturating it.

Only management plane is centralized. Control and data plane are distributed. management plane constitutes of Configuration, monitoring, firmware upgrades. So if you are not pushing expensive upgrades too often, i would still say the inter IAP traffic would be less than more prevalent L2 traffic e.g. ARP.

You can put two IAP in a cluster and find out how much of traffic is inter IAP in a normal usage scenario.

I am taking a snippet from VRD to show how inter IAP communication looks like.

chapter 1 instant communicatoins

=========

There are two major types of communication between APs in a cluster:

• L2 Broadcast messages for cluster maintenance and roaming

Master AP sends out a Layer 2 “beacon” message every second to notify that the master AP is currently active. This helps in new APs discovering the master and join the cluster & existing APs detecting master failover and take over as master of cluster.

There is also a session request message for Layer 2 roaming. When a client roams between APs in a cluster, a session request message is used to transfer client session and role data between APs

Sample frame for L2 communication:

• L3 unicast messages between IAPs (master and slave)

UDP messages on port 8211 between master and slave APs for config sync, firmware upgrade and control-plane messaging between APs.

Sample frame for L3 unicast communication:

Alright, thanks a lot for the time you've granted for me.

Sincerely yours,

Nicolas