8.1.WLAN Concepts and Components

• Enterprise-class WLANs, and even most WLANs in homes, are configured in such a way that a wireless client connects to some sort of a wireless base station, such as a wireless access point (AP) or a wireless router.

1.Wireless Routers

• Such a WLAN might be found in a residence whose Internet access is provided by digital subscriber line (DSL) modem.

• In this topology, a wireless router and switch are shown as separate components.

  1. The wireless router obtains an IP address via DHCP from the Internet service provider (ISP).

  2. Then the router uses Port Address Translation (PAT) to provide IP addresses to devices attaching to it wirelessly or through a wired connection.

• However, in many residential networks, a wireless router integrates switch ports and wireless routing functionality into a single device.

• The process through which a wireless client (for example, a laptop or a smartphone) attaches with a wireless router (or wireless AP) is called association .

2.Wireless Access Point

• Although a wireless access point (AP) interconnects a wired LAN with a WLAN, it does not interconnect two networks (for example, the service provider’s network with an internal network).

• The AP connects to the wired LAN, and the wireless devices that connect to the wired LAN via the AP are on the same subnet as the AP.

• No Network Address Translation [NAT] or PAT is being performed.