What is Ethernet (IEEE 802.3)?

Ethernet describes a tech­no­logy for cabled data networks that connect software and/or hardware with each other. This mostly takes place via LAN cables, which is why Ethernet is also sometimes referred to as LAN tech­no­logy. In this way, Ethernet enables data exchanges between end devices. These could be computers, printers, servers, routers, or others. When combined into a local network, these devices establish con­nec­tions via the Ethernet protocol and can exchange data packages with one another. The current and most widely dis­trib­uted protocol is IEEE 802.3.

Ethernet was developed back in the early 1970s, but the network system was ori­gin­ally only used in­tern­ally by the company Xerox. At the start of the 1980s, Ethernet was developed into a stand­ard­ised product. However, Ethernet still wasn’t widely used until the middle of the decade when several man­u­fac­tur­ing companies started to work with Ethernet and related products. The tech­no­logy made a sig­ni­fic­ant con­tri­bu­tion to the way that the personal computer re­volu­tion­ised the working world. Today, the widely-dis­trib­uted IEEE standard 802.3 is used in offices, private house­holds, con­tain­ers, and carriers.

While the first version of the tech­no­logy only had a speed of 3 megabits per second, Ethernet protocol today enables speeds of up to 1.000 megabits per second. Earlier Ethernets were limited to a building, but today Ethernet can cover a range of just over 6 miles with the use of fiber optic cables. Over the course of its de­vel­op­ment, Ethernet has taken over a dominant role among LAN tech­no­logy and out­per­formed various com­pet­it­ors. In addition, today real-time Ethernet is the industry standard for com­mu­nic­a­tion ap­plic­a­tions.

Ori­gin­ally, each message that was sent within a network went to all connected devices. These then had to filter through all received data and decide whether it was relevant to them. This common bus enabled broadcast messages, but also recorded all data traffic for each member – clearly a security gap of early Ethernet. Data could be encrypted, but data traffic itself couldn’t be in­di­vidu­ally con­trolled. Hubs also couldn’t close this security gap. Bridges and switches are a solution in modern networks, as they can be used to segment the Ethernet.

This tech­no­logy doesn’t solve all problems, though. Abuse by MAC flooding or MAC spoofing, for example, still poses a danger for the stability of the network and the security of the com­mu­nic­ated data packages. Working securely with Ethernet therefore requires serious use of all connected systems and regular data analysis (e.g. LAN analysis) to uncover potential cases of misuse or dis­turb­ances.

As long as an Ethernet’s data amount isn’t at capacity, it functions well. Capacity util­isa­tion rates of more than 50 percent can cause data jams, though. As personal computers developed tech­no­lo­gic­ally and con­tinu­ously increased their data volume, Ethernet networks also had to develop further to keep pace with the progress of tech­no­logy. Switches are re­spons­ible for ef­fi­ciently dividing data packages and min­im­ising the risk of col­li­sions. Modern cable tech­no­lo­gies like twisted pair and fiber optic have higher transfer rates meet the modern re­quire­ments for a network.

Another in­nov­a­tion is ‘Ethernet flow control’. With this mechanism, data transfer can tem­por­ar­ily be stopped to alleviate data flow from another location. This is es­pe­cially practical in full-duplex mode when a network serves a re­l­at­ively high number of end devices. The flow control for specific members of the network is tem­por­ar­ily cut off to optimise the overall re­li­ab­il­ity of the network. This can also cause losses in speed, though, which can then be stemmed by other mech­an­isms such as the trans­mis­sion control protocol.

In the past, Ethernet primarily used con­ven­tion­al coaxial cables. Today, twisted pair copper cables and fiber optical cables are the industry standard, as they enable much faster transfer rates and a larger range. Another advantage is that copper cables can also supply power to connected devices. This method, called ‘power over Ethernet’ (PoE), is specified in IEEE 802.3af and enables energy-efficient networks.

Ethernet developed from ALOHAnet, a radio-based network from the Uni­ver­sity of Hawaii. In the Xerox Palo Alto Research Center, the visionary Robert Metcalfe was already working on an early version of the cabled Ethernet protocol at the beginning of the 1970s. It was intended to make work within the company easier first, and then be actively tested. The test phase peaked in 1976 with a sci­entif­ic paper, published by Metcalfe together with David Boggs. It described local networks of connected personal computers.

In 1979, Metcalfe founded his own company 3com to push forward with the de­vel­op­ment of computers and LAN and establish Ethernet as standard. In 1980, he made his break­through with the adoption of Ethernet 1.0, which was then further developed by the Institute of Elec­tric­al and Elec­tron­ics Engineers (IEEE). This process led to the invention of other tech­no­lo­gies, including the CSMA/CD (carrier sense multiple access/collision detection) protocol, which later became known as IEEE 802.3. It also brought about the ground­break­ing protocols token bus (802.4) and token ring (802.5).

Between 1983 and 1986, the in­nov­a­tions Chea­p­er­net, Ethernet-on-Broadband, and StarLAN arrived on the scene before the Ethernet standard had started to receive more attention from many man­u­fac­tur­ers. As a result, some small companies started to use Ethernet networks in the workplace, but still via telephone-based four-wire lines. Ethernet con­nec­tions via twisted pair and fiber optic cables weren’t developed until the early 1990s, which lead to the in­tro­duc­tion of the 100 MB/s standard for Ethernet according to IEEE 802.3u in 1995. A standard for wireless LAN (802.11) was adopted at the same time. 1995 is con­sidered the birth year of the modern internet.