ISO/IEC 8802 local area networks (LANs) of all types can be connected together using MAC bridges. Each individual LAN has its own independent MAC. The bridged LAN created allows the interconnection of stations as if they were attached to a single LAN, although they are in fact attached to separate LANs each with its own MAC. A MAC bridge operates below the MAC service boundary, and is largely transparent to protocols operating above this boundary, in the Logical Link Control (LLC) sublayer or Network layer. The presence of one or more MAC bridges can lead to differences in the quality of service provided by the MAC sublayer; it is only because of such differences that MAC bridge operation is not fully transparent.