Service set identifier

In computer networking, a service set is a set consisting of all the devices associated with a consumer or enterprise IEEE 802.11 wireless local area network (WLAN). The service set can be local, independent, extended or mesh.

Service sets have an associated identifier, the Service Set Identifier (SSID), which consists of 32 octets that frequently contains a human readable identifier of the network.

The basic service set (BSS) provides the basic building-block of an 802.11 wireless LAN. In infrastructure mode, a single access point (AP) together with all associated stations (STAs) is called a BSS; not to be confused with the coverage of an access point, known as the basic service area (BSA). The access point acts as a master to control the stations within that BSS; the simplest BSS consists of one access point and one station.

The IEEE 802.11s amendment defined an additional protocol for wireless mesh networks. Only mesh STAs participate in mesh functionalities such as formation of the mesh BSS, path selection, and forwarding. Accordingly, a mesh STA is not a member of an IBSS (independent BSS) or of an infrastructure BSS. Consequently, mesh STAs do not communicate with nonmesh STAs. However, instead of existing independently, an MBSS can interconnect with other BSSs through the DS (Distribution System). Mesh STAs can communicate with nonmesh STAs through a logical architectural component called a Mesh Gate.

With 802.11, one can alternatively set up an ad hoc network of client devices without a controlling access point; the result is called an IBSS (independent BSS).

An extended service set (ESS) is a set of two or more interconnected wireless BSSs that share the same SSID (network name), security credentials and integrated (that is, providing translation between 802.3 and 802.11 frames) wired local area networks that appear as a single BSS to the logical link control layer at any station associated with one of those BSSs. This facilitates mobile IP and fast secure roaming applications. Furthermore, the BSSs may work on the same channel, or work on different channels to boost aggregate throughput.

...
Wikipedia