to transmit bits over a medium; to provide mechanical and electrical specifications  defines: physical characteristics, representation of bits, data rate, sychronization, line configuration, physical topology, transmission mode
to transmit bits over a medium; to provide mechanical and electrical specifications  defines: physical characteristics, representation of bits, data rate, sychronization, line configuration, physical topology, transmission mode
defines the physical characteristics of the transmission medium (connectors, pins, electrical currents, encoding, light modulation, etc) rj-45, ethernet (ieee 802.3) lan hub, lan repeater, cables