Service set (802.11 network)

In IEEE 802.11 wireless local area networking standards (including Wi-Fi), a service set is a group of wireless network devices which share a service set identifier (SSID)—typically the natural language label that users see as a network name. (For example, all of the devices that together form and use a Wi‐Fi network called Foo are a service set.) A service set forms a logical network of nodes operating with shared link-layer networking parameters; they form one logical network segment. A service set is either a basic service set (BSS) or an extended service set (ESS). A basic service set is a subgroup, within a service set, of devices that share physical-layer medium access characteristics (e.g. radio frequency, modulation scheme, security settings) such that they are wirelessly networked. The basic service set is defined by a basic service set identifier (BSSID) shared by all devices within it. The BSSID is a 48-bit label that conform to MAC-48 conventions. While a device may have multiple BSSIDs, usually each BSSID is associated with at most one basic service set at a time. A basic service set should not be confused with the coverage area of an access point, known as the basic service area (BSA). An infrastructure BSS is created by an infrastructure device called an access point (AP) for other devices to join. (Note that the term IBSS is not used for this type of BSS but refers to the independent type discussed below.) The operating parameters of the infrastructure BSS are defined by the AP. The Wi‐Fi segments of common home and business networks are examples of this type. Each basic service set has a unique identifier, a BSSID, which is a 48-bit number that follows MAC address conventions. An infrastructure BSSID is usually non-configurable, in which case it is either preset during manufacture or mathematically derived from a preset value such as a serial number or a MAC address of another network interface. As with the MAC addresses used for Ethernet devices, an infrastructure BSSID is a combination of a 24-bit organizationally unique identifier (OUI, the manufacturer's identity) and a 24-bit serial number.