Network control architecture

With a central controller

In a controller-based wireless mesh network, there is one central authority that configures the entire network. The controller has a holistic view of the network and drives typically light-weight access points or mesh nodes. These nodes rely on the presence of the controller for their configuration and operation. Often times, multiple controllers may exist on the network to deal with different aspects of the operation, such as IP mobility.

In a multi-radio mesh network, a controller has a complete view of all the links in place, and can make well-informed decisions to properly allocate frequencies and bandwidth. However, this central controller places another “box” to be on the network, and often presents a single point of failure. If the controller goes down for some reason, it could have a severe impact on the network’s operations. The main advantage of using a centralized approach is that any configurational change only needs to be done once, and it will be pushed out throughout the network.

Without a central controller

Some wireless mesh networks, such as a Meshbone network, do not require the presence of a central controller. Sometimes referred to a “fat” nodes, in contrast to the light-weight nodes in a controller-based scheme, the mesh devices talk to each other in a peer-to-peer fashion for their operations.

While avoiding the setup and maintenance of a central controller, a multi-radio distributed mesh network is faced with the challenge of properly allocating the frequencies used by individual mesh links. Without having knowledge of the entire network, how can each node now make well-informed decision on which links to form on which frequencies, without causing too much disruption for others. Meshbones’s algorithm offers a solution to this problem in a fully distributed fashion, including features such as IP mobility.

In a controller-less network, the same advantages of the centralized approach may be achieved, but greater care must be taken to ensure that any change in configuration is properly propagated throughout the mesh network.