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The first wave of wireless LANs saw autonomous access points being deployed in key verticals such as healthcare, retail and manufacturing where there was overwhelming business advantage to having users and devices connecting to the network wirelessly. These autonomous (standalone or fat) access points were relatively simple to deploy but lacked the manageability, mobility, and security features that enterprises required, even for convenience networks. The lack of manageability and control increased the operational costs of these wireless LANs.
The time associated with carrying out pre-installation site surveys, AP location tuning, periodic post-installation surveys and the per-AP configuration and image updating drove organizations to look for alternative solutions.
Centralized controller-based architectures emerged to address these issues and were able to add central management, allow fast device roaming, and provide coordinated RF management and security policies to these networks.
Unfortunately, they also added the complexity of an overlay network and a tremendous increase in the capital cost of the solution. While being able to reduce the wireless LAN management costs, most controller-based solutions approach 2 times to 4 times the capital cost of a traditional autonomous AP deployment, especially when the environment is mission-critical and the need for redundant controllers is factored in to the equation.
Aerohive Networks cooperative control architecture is based on a new category of wireless infrastructure equipment called a Cooperative Control Access Point (CCAP) which provides a simple and logical alternative for deploying wireless LAN infrastructures. A network based on Aerohive Networks cooperative control access points, called HiveAPs, can easily and cost-effectively be rolled out to support greenfield wireless LAN deployments, and can also provide a seamless upgrade for legacy autonomous access points, providing all of the benefits of a controller, without the need to add controllers or re-architect the network. The cooperative control functionality enables multiple HiveAPs to be organized into groups, called ”hives”, that share control information between HiveAPs to enable functions like fast layer 2 and layer 3 roaming, coordinated RF management, security, load balancing, high availability and mesh networking, allowing these functions to be provided in a controller-less architecture. Centralized configuration, monitoring and reporting is provided by a central network management system, called the HiveManager. This management appliance can be located anywhere within the network and is not essential to the network’s ongoing operation.
Cost Disadvantages of a Controller-based Wireless LAN Architecture
While there are definitely operational advantages associated with controllerbased architectures over legacy autonomous architectures, there are numerous issues associated the controller-based architectures that increase the capital and long term business cost of the wireless LAN solution. They include:
- Higher cost than comparable autonomous APs in all configurations
When controller-based architectures were first launched, expectations were that the thin APs that work with controllers would be significantly less expensive than traditional fat or autonomous APs, allowing the total capital cost of the solution to be competitive in spite of the added cost of the controllers. However this has not proven to be the case. So-called thin APs are increasingly needing to do more processing at the AP, and they are actually made with the same chipsets and components as fat APs, so their manufacturing costs – and in many cases their prices – are the same as autonomous APs. Because the controller-based solution requires that all packets be processed in two locations – the AP and the controller – the architecture requires twice as much hardware (mostly CPU and memory), which leads to approximately twice the cost, even in optimal configurations where controllers are fully loaded.
- Stair-step solution cost curve – cost per AP increases if controllers aren’t fully loaded
With controller-based architectures costs vary dramatically depending on the size of the controller and the degree to which you are able to, or want to, load the controller to its maximum AP capacity. Typically controller capacities don’t align precisely with the topology required to support the unique configuration and RF characteristics of the floors and buildings an enterprise may be faced with. As a result real-world enterprise deployments rarely hit the sweet spot in the controller cost curve because the enterprise network manager ends up buying excess controller capacity and has to spread the major cost increases as he steps up to the next largest controller across a small number of APs.
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