Ethernet is a family of wired technologies commonly used in local area networks (LAN) and wide area networks (WAN). It has been commercially available since 1980, but has been refined multiple times to support higher transmission rates, more nodes and longer distances while retaining much of its backward compatibility with older versions. Ethernet is still a key technology of the internet due to advances in technologies such as switches, bandwidth and networking.
History
Researchers at Xerox PARC developed the first version of Ethernet from 1973 to 1974. Xerox filed a patent for this technology in 1975 and deployed it at PARC in 1976. The company then released Ethernet to the public in 1980 after upgrading the original maximum speed of 2.94 Mbit/s to 10 Mbit/s protocol. Ethernet II was defined in 1982, which IEEE 802.3 formally standardized in 1983.
Switches
Inventors originally envisioned Ethernet as a broadcast medium for computers communicating through coaxial cable. However, nodes in a modern Ethernet communicate through a switch that forwards traffic to a destination node rather than using a single channel through a shared cable. This topology prevents data collisions unless a node and switch attempt to communicate with each other at the same time. The 10BASE-T variant introduced a full duplex mode of operation, which became the Ethernet’s de facto standard by the time Gigabit Ethernet was introduced in 1999. Full duplex mode allows a node and switch to send and receive simultaneously, making modern Ethernets almost entirely collision-free.
Bandwidth
The virtual elimination of collisions effectively doubles the bandwidth of Ethernet connections, since both devices can use the entire bandwidth for a particular segment. Furthermore, the constraints of collision detection no longer limit the length of a segment. In addition to the increased bandwidth, switching provides a greater isolation of devices from each other, allowing devices of different speeds to be easily mixed. As a result, switched Ethernet is currently the dominant network technology.
Networking
Ethernet uses advanced networking technologies to ensure its networks meet current performance expectations. For example, shortest path bridging (SPB) provides load-balancing through the use of the IS-IS routing protocol, which identifies the shortest route between devices. Spanning-tree protocol (STP) also provides physical loops for redundancy, especially beneficial for larger networks.
Furthermore, Ethernet’s advanced networking features include protective features such as port security and media access control (MAC) lockdown. It also uses virtual LANs to separate user classes on the same physical infrastructure, with multilayer switching between classes. Additional features of today’s Ethernet include link aggregation to increase bandwidth.
cables_16x9 flickr photo by tlsmith1000 shared under a Creative Commons (BY-SA) license
