Ethernet

Ethernet is a family of wired computer networking technologies used in many types of networks, like those in homes, schools, and offices. It was first introduced for sale in 1980 and became an official standard in 1983. As an open standard, it can be used by anyone, which has helped it become very popular.

Over time, Ethernet has been improved to work faster, over longer distances, and with more devices connected at once. It started with thick cables and has evolved to use thinner wires and even fiber optic links. Today, Ethernet can send data at speeds up to 800 Gbit/s, with even faster speeds being developed.

Ethernet works by breaking data into small pieces called frames. Each frame includes information about where the data is coming from and where it is going, as well as checks to make sure the data wasn’t damaged along the way. This helps ensure that data arrives safely and correctly.

Ethernet is used everywhere, from homes to big companies, and it works well together with wireless Wi-Fi networks. Because it carries Internet Protocol traffic, Ethernet is one of the essential technologies that help the Internet function.

History

Ethernet started as a way to connect computers using a shared connection. The idea came from a radio network made in the late 1960s by Norman Abramson at the University of Hawaii. This network helped computers talk to each other over the air.

In 1972, Robert Metcalfe and David Boggs used this idea for a cable network at Xerox Palo Alto Research Center. They made computers connect using a coaxial cable and named it "Ethernet" in 1973. Ethernet was better because it checked if the connection was free before sending messages.

Over the years, many people helped improve Ethernet. They made it faster and easier to use. In 1983, Ethernet became an official standard, meaning anyone could use the technology. This helped it become widely used in offices and homes. By the 1990s, Ethernet was the main way to connect computers in networks, and it kept getting faster with new versions like Fast Ethernet and Gigabit Ethernet.

Standardization

In February 1980, the Institute of Electrical and Electronics Engineers began working on a way to create rules for connecting small networks of computers, called local area networks (LANs). Different companies had different ideas about how to do this, which caused some disagreements.

Eventually, a group worked together to create a standard called CSMA/CD. This was approved by a European group in 1982 and later by the IEEE in 1985. Since then, the IEEE has kept updating the rules for Ethernet to make it faster and better. You can find the latest rules on the IEEE website.

Evolution

Ethernet has changed over time to include faster speeds, better ways to control how data is sent, and different types of wires to carry the data. The old coaxial cables were replaced with direct connections using Ethernet repeaters or switches.

Ethernet devices talk to each other by sending small blocks of data called data packets. Each device has a unique address called a MAC address, which helps make sure the right device gets the right packet. This address is used to know where the packet is coming from and where it is going.

Because Ethernet is common and the cost to use it keeps going down, most computers have Ethernet built right into them, so there is no need for an extra network card.

Shared medium

Originally, Ethernet used a shared cable where all devices could talk at the same time, like a radio broadcast. This made things simple but also caused problems when two devices tried to send data at the same time, creating a clash.

The first Ethernet used thick cables, but later it switched to thinner cables that were easier to install. Since everyone shared the same cable, any data sent by one device could be seen by all devices, even if it was only meant for one. This sharing of the cable meant that the speed was split between devices. If two devices tried to send data at the same time, it could mess up the data and make them send it again.

Today, Ethernet usually uses switches. Each device talks to its own switch, so there are fewer clashes and better speed.

Repeaters and hubs

To make networks bigger, devices called repeaters were used. These could help stretch the network further by boosting the signal. Later, hubs were introduced, which let more devices connect in a star shape.

Using twisted-pair wires, like those used for phones, made Ethernet easier to set up in offices. This led to the development of 10BASE-T, which changed repeaters into something needed for any network with more than two devices.

Bridging and switching

Repeaters had limits; they sent all data to every device and could not mix different speeds. Bridging solved some of these problems by only sending data where it needed to go, which improved speed and allowed mixing different speeds.

The first Ethernet switches appeared in the late 1980s. These switches look at the whole packet before sending it on, which helps avoid mistakes. With switches, devices can send and receive data at the same time without clashes, doubling the speed.

Advanced networking

Even with switches, there are still issues like single points that can fail, security problems, and difficulties in making large networks. Advanced switches use special protocols to avoid loops, keep networks secure, and manage different types of traffic. Ethernet is now used in supercomputers and industrial systems, working alongside other types of networks.

Varieties

Ethernet has changed a lot over time and can use different kinds of wires and glass to send information. It can go from slow speeds to very fast speeds. One of the first ways it used regular wires with special plugs, and this idea was used for many years.

Today, the most common types of Ethernet use twisted wires with special connectors. They can work at different speeds. There are also versions that use glass wires, which are great for big networks because they can send information far and keep it clear. No matter which type you use, the way computers talk to each other stays about the same.

Frame structure

In IEEE 802.3, a datagram is called a packet or frame. A packet includes parts like the preamble, start frame delimiter, and sometimes extra bits. The frame starts with a header that has addresses and a type field. The middle part holds the actual data, like information from the Internet Protocol. The frame ends with a special check to make sure the data wasn’t mixed up while moving.

Autonegotiation

Main article: Autonegotiation

Autonegotiation is a way for two devices connected together to agree on how to send information, like how fast and in what mode. This idea was first used with a faster type of Ethernet in 1995 and became a requirement for even faster types starting in 1998. It helps devices work together smoothly.

Error conditions

Switching loop

Main article: Switching loop

In computer networks, a switching loop happens when there are multiple paths between two points. This can cause messages to be sent over and over again, filling up the network with too much traffic. To stop this, special rules are used to make sure the network works without getting stuck in loops.

Jabber

Sometimes, a device might send messages that are too long. This is called "jabbering." Different parts of the network have ways to notice this and stop it. For example, some devices can stop sending messages if they go on too long, and others can ignore the extra messages to keep everything running smoothly.

Runt frames

Very small messages that are too short to be proper network messages are called "runts." These are ignored and not passed along in the network.