(a division of Cisco Systems Inc.)) Chapter Three Wireless LAN Switches or Controllers In a large wireless network, typically in a corporate environment with tens and perhaps hundreds of access points, the need to individually configure access points can make WLAN management a complicated task. Wireless LAN switches simplify the deployment and management of large-scale WLANs. A wireless LAN switch (also known as a wireless LAN controller or access router), is a networking infrastructure device designed to handle a variety of functions on behalf of a number of dependent, or "thin", access points (Figure 3-11). As shown in Table 3-2, this offers several advantages for large-scale WLAN implementations, particularly those supporting voice services. The driver behind the development of the wireless switch is to enable the task of network configuration and management, which becomes increasingly complex and time consuming as wireless networks grow. A wireless switch provides centralised control of configuration, security, performance monitoring and troubleshooting, which is essential in an enterprise scale wireless LAN. Taking security as an example, with WEP, WPA, and 802.11i, all potentially in use at the same time in a large WLAN deployment, if security Table 3-2: "Thin" Access Point Advantages Advantage Description Lower cost A "thin" access point is optimised to cost effectively implement wireless communication functions only, reducing initial hardware cost as well as future maintenance and upgrade costs. Simplified access point Access point configuration, including security functions, management is centralised in order to simplify the network management task. Improved roaming Roaming handoffs are much faster than with conventional performance access points, which improves the performance of voice services. Simplified network The centralised command and control capability makes it upgrades easier to upgrade the network in response to evolving WLAN standards, since upgrades only have to be applied at the switch leve