Ethernet Protocol

In its most basic form, a network is a connection of two computers, which collaborate on a particular task. The tasks may range from simple file sharing to the complex distributed computing or clustering. The two basic components of a network are the physical medium and the network protocol. Ethernet protocol works on the baseband networking technology, which has been defined by various standards. The major elements of Ethernet are Ethernet packets, Ethernet access method, hardware cables, connectors and circuitry. Ethernet is a dominant technology, which was developed in phases, at Xerox PARC, between 1973 to 1975. Its patent was filed by Xerox in 1975, listing Robert Metcalfe, Chuck Thacker, David Boggs and Butler Lampson, as inventors. Ethernet protocol was designed and implemented as a packet-switching LAN over broadcast technology. In 1985, the IEEE 802.3 standard for Ethernet was defined, and implemented at the Network Interface layer of the TCP/IP model.

The Ethernet protocol is most widely used for network connectivity. It uses an access method called CSMA/CD (Carrier Sense Multiple Access/Collision Detection), in which the computer in a network listens to the cable, before sending anything through the network. With CSMA/CD, it is normal to have collisions as two computers may attempt to send data at the same instance. However, the delay caused by collisions and retransmitting of data, is very small and does not effect the speed of transmission on the network. The Ethernet protocol is applicable for linear bus, star or tree topologies, and the data can be transmitted through this protocol, over wireless access points, twisted pair, coaxial or fiber optic cable, at a speed of 10 Mbps up to 1000 Mbps.

In the beginning of Ethernet implementations, coaxial cables were generally used to connect the stations to each other. The two forms of coaxial cables are 10Base5 (thick Ethernet) and 10Base2 (thin Ethernet). A 10Base2 cable allows connection of up to 30 nodes, over a maximum distance of 185m, whereas, a 10Base5 uses 10mm wide coaxial cable which can connect up to 100 nodes over a maximum distance of 500m. 10BaseT is also an older standard networking technology which is used in offices or homes. It uses cables with wires that are twisted in pairs, and a hub or switch, which allows the connection of multiple computers. 10BaseT can operate at 10Mbps or 100 Mbps, with a maximum range of 100 meters, and it uses a star physical topology.

1 Gigabit Ethernet allows the data transmission rate of 1 Gbps, and is primarily used for backbones on a network. It can be implemented with both fiber optical cables and copper ones. 1 Gigabit Ethernet replaced the Fast Ethernet, becoming a Network interface upon new PC's. Other 1 Gigabit cables include, 1000BASE-T, 1000BASE-SX, 1000BASE-LX and 1000BASE-CX. There are also 10 Gigabit cables which encompass media types for single-mode fibre, multi-mode fibre, copper backplane and copper twisted pair. These cables include 10GBASE-SR, 10GBASE-LX4, 10GBASE-LR, 10GBASE-ER, 10GBASE-SW, 10GBASE-LW, 10GBASE-EW and 10GBASE-T. 10 Gigabit Ethernet is still an emerging technology, and its standard for commercial acceptance is not yet decided. An Ethernet address is the unique hardware address of a device on a network. It is also known as the media access control (MAC) address, and is 48 bits long, displayed as 12 hexadecimal digits.

According to Interactive Data Corp. (IDC), in 2008, 350 million Ethernet switch ports were pushed out into the world. Because of the ubiquity of Ethernet and the low cost of the hardware needed to support it, most of the manufacturers now build the functionality of an Ethernet card directly into the PC motherboards, eliminating the hassles of its manual installation by the end user.