Network bridges connect one network to another so that terminals on both networks can communicate as if they were part of a single network. Network bridges provide the connectivity required for communications between dissimilar segments of a local area network (LAN). For example, a network bridge can connect an Ethernet LAN segment to a token ring LAN segment. Network bridges are specified under the IEEE 802.1D standards from the Institute of Electrical and Electronics (IEEE). They are not protocol-dependent because they operate at the Data Link Layer (layer 2) of the Open Systems Interconnection (OSI) reference model.