Introduction to access controller and control functions in WLAN Switches

WLAN switches are still commonly used. So I have studied the Access Controller and control functions in WLAN switches. I will share them with you here, hoping they will be useful to you. Moderate AP is also getting more and more popular, because they combine the advantages of fat AP and thin AP. Moderate AP can use AC for the actual WLAN switch while providing wireless encryption. This method is used to use the latest new AP that supports the WPA2 wireless chipset. management and policy functions are executed by controllers that connect to multiple APS through tunnels.

In addition, moderate AP also provides some additional features, such as DHCP relay that allows the base station to obtain IP addresses through DHCP. In addition, a moderate AP can perform VLAN tag Based on the Service Set Identifier (SSID), so that the client can associate with the AP (when the AP supports multiple SSID ). Moderate AP supports two types of MAC deployment: Local MAC and separated MAC Architecture. Local MAC indicates that all wireless MAC functions are executed on the AP. All 802.11 MAC functions (including management and control frame processing) are executed by the AP. These features include time-sensitive features (also known as real-time MAC ).

The MAC function is allocated between the AP and the Controller. Real-time MAC functions include beacon generation, detection of signal transmission and response, control frame processing (such as Request to Send and Clear to Send, namely, RTS and CTS), and re-transmission. Non-real-time functions include identity authentication and unauthentication, association and re-Association, bridging between Ethernet and wireless LAN, and segmentation. Different vendors have different ways of assigning features between the AP and controller. In some cases, even their real-time definitions are different. A common moderate AP implementation includes local MAC and AP management and control functions.

Access Controller and control functions

The next key component of the centralized WLAN switch architecture is the access controller (AC ). In the following article, we think that the controller function is deployed on a WLAN switch and the function is called AC. We also use the word "WTP" to refer to AP (including fat, thin, or moderate ). The IETF's Wireless Access Point Control and configuration (CAPWAP) team is defining interfaces and protocols between the AP and Its controlled WTP. This section uses the CAPWAP framework to describe the interfaces between AC and WTP. [3, 4, 5] The following functions can be implemented through an interface between the AC. WTP and the AC through a L2 (Exchange) or l3 (route) network:

◆ Discover and select an AC through WTP

◆ Download firmware to WTP through AC-after startup and WTP triggering

◆ Functional negotiation between WTP and AC

◆ Two-way authentication between WTP and AC

◆ Configuration, status, and statistics of WLAN switches between WTP and AC

◆ QoS ing between wired and wireless network segments between campus networks and the Internet

CAPWAP protocol used for configuration and control between the AC and WTP of the second/third layer network

In addition, although CAPWAP does not clearly define all details, the AC can perform wireless resource management (RRM) by configuring and monitoring different access points in the region it controls) and malicious AP detection. The scope of these features varies depending on the vendor deployment method. Another important feature provided by AC is mobile management. The following sections provide