Advances in Wireless LAN Architecture: The Aerohive Cooperative Control Architecture

Advances in Wireless LAN Architecture:
The Aerohive Cooperative
Control Architecture
A Farpoint Group White Paper
Document FPG 2007-227.1
May 2007 Farpoint Group White Paper - May 2007
hile many have assumed contemporary switched or controller-based implementa-tions represent the end of the road with respect to WLAN architecture, the high degree of variability evident in modern controller-based architectures should sWerve as an indicator that such is hardly the case. Indeed, innovations in wireless LAN archi-tecture continue to appear, as is witnessed by the announcement of a distinctive new ap-proach from Wi-Fi startup Aerohive Networks [http://www.aerohive.com/]. In some ways, the Aerohive model is reminiscent of the original traditional/robust access point (AP) approach - we refer to these architectures as distributed, in opposition to the controller-based central-ized model that has dominated the thinking of the WLAN industry for the past seven years. In reality, both alternatives encompass a high degree of architectural variation, and we'll ex-plore the features and benefits of each in more detail below. Nonetheless, we believe the Aerohive architecture represents an interesting and innovative new direction in WLAN sys-tems design, with a combination of elements that define an interesting and important ap-proach to wireless-LAN system architecture. The Evolution of Wi-Fi System Architecture Early wireless LANs, before 1992, and with the exception of the first microcellular products from the Canadian firm Telesystems SLW, were almost always based on a peer-to-peer cli-ent model. A purely peer approach has major problems with scalability, in that all peer nodes in a given network must be able to "see", in a radio sense, every other node. This severely limits the value of the peer model - even though it survives today as ad hoc mode in the IEEE 802.11 standard, and is a widely-recognized security hole when enabled. Access points were initially used primarily as bridges between wireless clients and a wired infrastructure, rarely with support for roaming. As roaming between APs became a core justification and requirement for the installation of WLANs, providing the ability to grow and scale a given installation smoothly and economically, APs themselves consequently became more com-plex. Each had its own IP address, and each was configured independently. Soon a number of other issues with this "traditional" AP model became apparent, as follows: . Security - Wi-Fi security, no matter what form, only covers the airlink, that is, the connection between wireless client and an AP. It leaves the remainder of the network value chain either unprotected or in the domain of higher-level security techniques, such as virtual private networks (VPNs). . Management - Each AP is individually managed. While it is possible with some products to "make one AP look like another" and/or to use a central management tool or appliance, such is not the default in most cases, leading to serious management concerns once more than a few APs are deployed in any given case. . Roaming - Most APs lack support for Mobile IP or a similar mechanism for provi-sioning mobility across subnet boundaries. Of those that do, configuration can be-come very complex.
1 The Aerohive Cooperative Control Architecture Farpoint Group White Paper - May 2007
This state of affairs motivated the first major advance in WLAN architecture after the AP itself, us-ing what became known as gateways (see Figure 1A). This approach generally involved the use of one gateway product (an appropriately-packaged and -programmed single-board computer) con-nected to a number of APs, and then tunneling traffic from this box to a central management/controller box deeper in the network.
TraditionalAccessPoints "Thin"AccessPoints WAN
IPGateway Appliances Wireless LANController(Layer 3) ManagementAppliance (optional)1A 1B
Figures 1A and 1B - WLAN Architectural options. The gateway model (1A) was developed to correct fundamental deficiencies in the traditional AP model. The controller model (1B) with "thin" APs has been the dominant approach for the past five years. Source: Farpoint Group. In the early 2000s, however, most WLAN vendors realized that the high degree of common func-tionality in access points provided the motivation for moving much of this capability into what be-came know... [download for more]