BSSID, MAC Address
A Basic Service Set (BSS) is two or more wireless devices that are in communication with each other. Like every wired Ethernet device, every wireless device has a fixed, unique “media access control” (MAC) address. When wireless devices establish communication, they automatically select the MAC address of one BSS member as an identifier for the group; this is the BSSID.
It has become customary to refer to a wireless device’s MAC address as its BSSID even when the address is not being used to identify an active BSS.
A BSS that includes an access point is often referred to as a cell.
SSID, Domain Identifier
A Service Set Identifier (SSID) is a shared name, usually assigned by a network administrator, that identifies wireless devices that are allowed to communicate with each other. This is one way of providing basic security on a wireless network. An SSID can be up to 32 characters long, and can include letters and numbers.
Giving multiple access points the same SSID and encryption settings allows mobile stations that also share those settings to “roam” from one AP to another. When at least one AP is among the devices sharing an SSID, the name may be referred to as an Extended Service Set Identifier (ESSID).
An SSID is sometimes called a “domain name,” but it is unrelated to the domain names used to identify machines and networks on the Internet. Other terms for SSID are domain ID, net ID, network name, extended network ID, and wireless network name. The set of devices that an SSID identifies is sometimes called a communication domain or wireless domain.
Figure 3 shows a common wireless network setup. If the APs share SSID and encryption settings, mobile devices that also share those settings can roam among them.
Figure 3. Roamable multi-AP infrastructure network
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