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Overview - Architectures



There are a several Wireless LAN architectures. For indoor networks, you have the Single MAC model and the Split MAC model.

Single MAC model
The logic for processing the MAC layer operation is within the access point. We call this a smart access point. Those access points are autonomous/standalone access points and are managed individually. A benefit of this is that there is no single point of failure but it is harder to support since it is decentralized. There are multiple names for this model: controller-less, thick/fat access points, or intelligent Edge/Distributed architect.

Split MAC model
The MAC layer operations are split between the access point and the wireless LAN controller. In enterprise environments, you see mostly split MAC model since they are centrally managed. When you have a lot of access points, it will take time to configure them individually. Controller-based architecture is another name for this model, but this has problems as well because when the controller is down, your whole wireless network will be down as well (there are possibilities for redundancy).

Those above two models are for indoor networks, but can be used for outside as well. The model that normally is used for outside is Wireless Mesh model.

Wireless Mesh model
In this model, all the access points are connected to each other and the data is traveling from access point to access point. You use this model when there are many obstructions or in places where it is not easy to put wires for the access point. Again, those places are mostly outside. Wireless Mesh is part of the 802.11s amendment.

WLAN Network Management System (WNMS)
This looks like a split MAC model, but it is slightly different. The WNMS or centralized management with distributed processing is a management interface, but all the access points are still fat access points. Through the WNMS you can rollout firmware, but you still need to configure every single access point. This model is in between Single MAC model and Split MAC model. Single MAC is smart access points and Split MAC has dumb access points that rely only on the controller.

Hybrid WLAN Architecture
To make it more complex, Hybrid WLAN model is based on the WNMS model in combination with the Split MAC model. You can configure some functionality on the access point from the controller and some of the configuration needs to be done on the access point itself. Avaya has a similar model like this. Avaya WLAN Orchestration System is a system that can push configuration to the access point, but you can still manage the access point as an autonomous access point.

Unified WLAN Architecture
When we talk about a controller in the previous models, we have a separate device that takes over the intelligences. In the Unified model that device is integrated into the wired network. For example, the Cisco Wireless Services Model (WiSM) that can be integrated in a Cisco Catalyst modular switch.

Cloud-based Architecture
One of the latest developments is to put everything in the cloud. Meraki and Aerohive are an example of this. The access points are managed in the cloud with resources from the vendor.