Ethernet (IEEE 802.3) stands for a 1-persistent CSMA/CD LAN. The basic idea here is that a host listens to the cable first when it wants to transmit. If the cable is busy, the host waits until it goes idle; otherwise it transmits immediately. If two or more hosts simultaneously begin transmitting on an idle cable, they will collide. All colliding hosts then terminate their transmission, wait a random time, and repeat the whole process all over again. The protocol is simple and hosts can be installed on the fly without taking the whole network down. On the other hand, to know for sure that the frame it just sent did not collide with any other frame, the transmitter need to send a minimum of 64 bytes in the frame. This could represent a substantial overhead. Other disadvantages of Ethernet include nondeterministic, priorityless, and less efficient as the speed increases.
Ethernet is the most widely-installed local area network ( LAN) technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox from an earlier specification called Alohanet (for the Palo Alto Research Center Aloha network) and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI, and ARCNET. The primary alternative for contemporary LANs is not a wired standard, but instead a variety of IEEE 802.11 standards also known as Wi-Fi.
The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet. Fast Ethernet or 100BASE-T provides transmission speeds up to 100 megabits per second and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1000 megabits per second (1 gigabit or 1 billion bits per second). 10-Gigabit Ethernet provides up to 10 billion bits per second.
Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted. As per the OSI model, Ethernet provides services up to and including the data link layer.