802.3 is a standard specification for Ethernet, a method of packet-based physical communication in a local area network (LAN), which is maintained by the Institute of Electrical and Electronics Engineers (IEEE). In general, 802.3 specifies the physical media and the working characteristics of Ethernet. The first Ethernet standards to be defined support a data rate of 10 megabits per second (Mbps) and specify these possible physical media:
- 10BASE5 (Thickwire coaxial cable with a maximum segment length of 500 meters)
- 10BASE2 (Thinwire coaxial cable with a maximum segment length of 185 meters)
- 10BASE-F (optical fiber cable)
- 10BASE-T (ordinary telephone twisted pair wire)
- 10BROAD36 (broadband multi-channel coaxial cable with a maximum segment length of 3,600 meters)
This designation is an IEEE shorthand identifier. The "10" in the media type designation refers to the transmission speed of 10 Mbps. The "BASE" refers to baseband signalling, which means that only Ethernet signals are carried on the medium (or, with 10BROAD36, on a single channel in a shared cable). The "T" represents twisted-pair; the "F" represents fiber optic cable; and the "2", "5", and "36" refer to the coaxial cable segment length in 100 meter sections (the 185 meter length has been rounded up to "2" for 200).