Access Points and Wireless LAN Controllers Explained

Access points and wireless LAN cards connect devices in a network using radio signals. This tutorial compares both and explains their key differences and how they function in a network.

Access point

An access point is the device that allows multiple wireless devices to connect. Just as a HUB or switch connects multiple devices in a wired LAN, an access point connects various wireless devices in a wireless network. It can also extend a wired network to wireless devices.

Based on their functions, you can categorize an access point into three types: standalone, multifunction, and controlled.

Standalone access point

A standalone access point provides the same functionality in a wireless network that a switch or hub provides in a wired network. It provides connectivity between the different wireless devices. It accepts frames from the connected device and, based on the destination device's physical address, forwards them to the destination device.

Both the wired and wireless networks use different networking standards. A wired network uses Ethernet standards, while a wireless network uses IEEE 802.11 (Wi-Fi) standards. A device that only understands and supports one type of standard, either Ethernet or Wi-Fi, cannot process frames formatted in the other kind of standard. For example, a regular Ethernet switch neither understands the frame format defined by Wi-Fi standards nor processes it.

Access point supports both standards. Based on the destination device, it converts the received frame before forwarding it. For example, suppose it gets a frame formatted according to Wi-Fi standards and with an Ethernet destination address. In that case, it formats it with Ethernet standards before forwarding it to the destination.

An access point uses radio signals for connectivity. Any device within its signal range can connect to it. This feature makes it more flexible but less secure than a regular Ethernet switch. To enhance security and stop unauthorized access, the Access Point uses an authorization feature. Based on the security and flexibility requirements, you can configure it to allow all users or selected users.

Multifunction Access Point

A multifunction access point is the combination of two or more devices. In this combination, one or more devices are merged with the access point to provide additional functionality alongside the access point's existing functionality. A wireless router that an ISP uses to provide an Internet connection is an example of a multifunction access point. It consists of three devices: an access point, a regular Ethernet switch, and a router.

Controlled Access Point

A controlled access point works as the client of the Wireless LAN Controller (WLC). Technically, it is known as the Lightweight Access Point (LWAP). LWAP does not take any forwarding decision. Upon receiving a frame from the connected device, instead of forwarding it to the destination device, it forwards that frame to the WLC. The WLC, based on the security configuration, decides whether to forward or discard the received frame. If it decides to forward, it sends the frame to the LWAP connected to the destination device. The LWAP then sends it to the destination device.

The WLC-LWAP setup is typically used in a company environment to span a single wireless network across a large geographical area. This setup allows users to roam throughout the office, campus, or building while remaining connected to the network. In this setup, it does not matter which LWAP a user uses to send and receive frames, as long as the same WLC controls that LWAP. Since the WLC takes all forwarding decisions, an LWAP does not allow direct communication between the two devices, even if they are both connected to it.

Key points

• An access point connects multiple wireless devices in a single wireless network.
• It supports both Ethernet and Wi-Fi standards.
• It uses radio signals to provide connectivity.
• Based on functionality, there are three types of access points: standalone, multifunction, and client.
• A standalone access point works in the wireless network exactly as the switch works in the wired network.
• To control unauthorized access, access points use authorization.
• To extend coverage, you can use multiple access points under a Wireless LAN Controller.
• An access point that works under the WLC is known as the LWAP (Lightweight Access Point).
• In the WLC-LWAP setup, the WLC controls and manages all LWAPs.
• An LWAP works as the bridge between the WLC and the end device.

Conclusion

Access points play a vital role in establishing connectivity in wireless networks, serving as bridges between wireless devices and wired networks. You can categorize them into three types: standalone, multifunction, and controlled. Each type offers unique capabilities to suit different networking needs. Standalone access points function similarly to wired switches, while multifunction access points combine additional functionalities such as routing. Controlled access points, or Lightweight Access Points (LWAPs), work in tandem with Wireless LAN Controllers (WLCs) to efficiently manage large networks and enable seamless connectivity across expansive areas.