 standard defines two modes of operation for a BSS; ad-hoc mode and infrastructure mode. An ad-hoc network is formed when a group of two or more 802.11 stations communicate directly with each other with no access point or connection to a wired network. This operating mode (also known as peer-to-peer mode) allows wireless connections to be quickly established for data sharing among a group of wireless enabled computers (Figure 6-2). Under ad-hoc mode the service set is called an independent basic service set (IBSS), and in an IBSS all stations broadcast beacon packets, and use a randomly generated BSSID. Infrastructure mode exists when stations are communicating with an access point rather than directly with each other. A home WLAN with an access point and several wired devices connected through an Ethernet hub or switch is a simple example of a BSS in infrastructure mode (Figure 6-3). All communication between stations in a BSS goes through the access point, even if two wireless stations in the same cell need to communicate with each other. This doubling-up of communication within a cell (first from sending station to the access point, then from the access point to the Table 6-2: 802.11 Network Components Component Description Station Any device that implements the 802.11 MAC and PHY layer protocols. Access point A station that provides an addressable interface between a set of stations, known as a basic service set (BSS), and the distribution system. Distribution system A network component, commonly a wired Ethernet, that connects access points and their associated BSSs to form an extended service set (ESS). Wireless LAN Standards Independent Basic Service Set (IBSS) Figure 6-2: Ad-hoc Mode Topology destination station) might seem like an unnecessary overhead for a simple network, but among the benefits of using a BSS rather than an IBSS is that the access point can buffer data if the receiving station is in standby mode, temporarily out of range or switched off. In infrastructure mode, the access point takes on