LAN Ethernets

What is an Ethernet?

In any office, home computer network, military network or industrial network, Ethernet technology likely plays a part. Ethernet technology is also known as IEEE 802.3.

If you're not familiar with the technical aspects of Ethernet, you're more than likely familiar with the everyday aspects of it. Ethernet cables are commonly referred to as network cables, simply because they are so ubiquitous as networking tools for computer networks. Ethernet networks typically use a modular connector, an RJ-45, and CAT5 cables to provide connections between devices.

Ethernet technology has made it possible to network very large systems of computers together with many different types of devices. The modular nature of the cords makes it easy for anybody to hook up an Ethernet connection between a modem, router, a server, a desk computer and any other device that accepts this type of the connection.

Ethernet technology was not always as easy to use as it is today. It has been around for a long time, however, and likely much longer than most people think.

 

When was Ethernet Developed and Standardized?

Ethernet has been in existence since somewhere between 1973 and 1974. It was developed by Xerox and inspired by a technology called ALOHAnet.

It would take until 1980 until Ethernet technology was common enough that it needed to be standardized. This was done by the Institute of Electrical and Electronic Engineers, commonly abbreviated IEEE under the name Project 802. The idea was to standardize technology used for local area networks, commonly abbreviated LAN.

In 1985, after great deal of debate, the IEEE finally standardized Ethernet under the 802.3 code.

 

History of Ethernet

Ethernet takes its name from the word ether, which was once the nebulous substance assumed to occupy space and also to make it possible for radio waves and electrical energy to propagate. The original patent application for Ethernet was filed by the Xerox company. On that patent application, filed in 1975, the inventors of the technology are listed as Butler Lampson, Chuck Thacker, Robert Metcalfe and David Boggs.

Metcalfe worked hard to promote Ethernet as a standard communication technology later in his career. There was competition, however, and Ethernet was not immediately accepted as the new standard for network communication. Competition came principally from Token Ring and Token Bus technology. These technologies were proprietary ones.

One of the things that made Ethernet viable as a standardized technology is the fact that it is inexpensive compared to other options. The original Ethernet connections used coaxial cable to carry signal, but that was soon displaced by the CAT5 network cables that people are familiar with today.

Over time, Ethernet has evolved to be faster, more reliable and is so universally utilize that just about every networked device comes with an Ethernet port on it these days. The addition of hardware to Ethernet networks, such as switches and hubs, enables networks to be expanded significantly for very low costs.

 

Who Developed It?

The primary inventors of the Ethernet communications technology are regarded to be Butler Lampson, Chuck Thacker, Robert Metcalfe and David Boggs. Like many advanced technologies, this one happened to be developed with the assistance of a large corporation – Xerox – and Xerox officially filed a patent for the technology.

Over time, other companies and other individuals have contributed greatly to the continued evolution of Ethernet as a viable communications technology and, in fact, the most commonly used communications technology in computer networking.

 

Who Standardized It?

 In order for a technology such as Ethernet to be officially standardized, it has to go through the IEEE. The IEEE was responsible for standardizing Ethernet and making a possible, to a great degree, for modern computer networks to start to be developed.

 

Evolution of Ethernet Since its Creation

To a great extent, Ethernet technology has evolved like the other technology that relies upon it over the years. It has become faster, more secure and more reliable than it has ever been before.

One of the most significant advances in Ethernet technology was the switching from coaxial cable to the modern CAT5 cable utilize on Ethernet networks. This allows much greater bandwidth and is quite inexpensive to install.

Initially, Ethernet networks were networks that consisted of a series of computers that were all wired together. Each computer had a connection to the same line, physically speaking. Over time, the use of repeaters and switches permitted Ethernet networks to move away from that design. This has some significant implications.

On early Ethernet networks, whenever a computer transmitted data every computer on the network received that data. On today's Ethernet networks, there is much greater control over who has access to data. Data can be transmitted to one computer or device specifically without transmitting that data to every single device on the network.

Whenever data is transmitted over an Ethernet network, it has information in the address that declares where the data came from and which machine it is intended for. If a machine receives data that was not intended for it, it can ignore that data, making the entire system faster and more secure.

Ethernet networks have also evolved over time to allow different protocols to be used by the same machine. The data identifies itself, so, again, data that is irrelevant to a given destination can simply be ignored but will be noted by the proper destination.

One of the interesting things about Ethernet technology is that, via a process called bridging, older Ethernet networks can be hooked to new Ethernet networks.

There has been one other significant development in Ethernet technology that has radically changed the way equipment is designed. Ethernet cards have become smaller and smaller over time. They have, at this point, become so small that they are typically integrated directly into a motherboard. This eliminates the need to attach a device to the motherboard externally or to use a PCI slot or a similar interface to install a separate network card onto a computer. Along with the simplification of Ethernet devices and the reduction hardware requirements, they have become much less expensive, making them more accessible and increasing their usage considerably.

 

What Does a Ethernet Topology Look Like?

Ethernet technology utilizes what is called a bus topology. In this type of a topology, every device on the network utilizes the same communication line to send and receive data. The devices are differentiated between by a unique address that each of them has. This is referred to as the MAC address.

In Ethernet topology, you'll run across a term called frames a lot. This is the format in which data is sent across the Ethernet network. A frame consists of the data that needs to be sent plus a header and a footer. These frames are limited in size to 1518 bytes.

Because all of the devices on an Ethernet network are using the same line to communicate, the addresses are vitally important for getting information to the right machine or other device, either of which is referred to as a "host" on an Ethernet network. Within the frame of data that is transmitted by any device, the address of the device that transmitted that data and the address of the intended recipient is included. You can think of it almost like an envelope containing a letter. On the letter, the address of the person who is intended to receive that letter is listed along with your address, which lets the recipient know who sent the letter just by looking at it. The data – the letter itself – is not available to anyone else in the system.

One of the problems with Ethernet technology is that multiple hosts can communicate at once. You can think of it like a room full of people all talking at once and, to get the idea of why this is a problem, imagine that you were trying to single out what one person was saying when 10 people were all talking over the top of each other. In Ethernet terminology, this cacophony is referred to as a collision. In order to prevent this from becoming an issue, algorithms are used to determine how much of a delay needs to be implemented before a device retransmits data after having a collision already.

Repeaters are often installed on Ethernet networks to increase the distance that data can be transmitted. A hub is a very popular type of repeater. A switch is a specific type of repeater that is more controlled and how it retransmits data than a hub, as is a router. There are also devices called bridges sometimes utilized on Ethernet networks. Bridges allow a connection between two networks that utilize different communications protocols.

There is an enormous variety of different devices that can be wired into an Ethernet network these days. All of these devices, however, are designed to work with the same topology and the same advantages and limitations that Ethernet networks provide. Over the years, this network topology has become the most common in the world, though there are some competing technologies out there. Wi-Fi connections work on the same topology as a regular Ethernet connection and, in fact, are simply wireless versions of Ethernet connections.

 

How Does Data Travel in an Ethernet?

When devices want to talk to each other on an Ethernet connection, the frame is everything. The frame, as described above, consists of the data that is being transmitted, plus the destination address and the originating address that apply. Frames are limited in size to 1518 bytes, so it may take many frames to actually transmit a substantial amount of data.

Today's Ethernet connection still utilize CAT5 cable and have for some time. This provides sufficient capacity for bandwidth, a very reliable medium and a very durable medium, all of which make CAT5 an excellent choice for computer networking.

For increased security, data may be encrypted in route to prevent it from being read or otherwise deciphered or it may be routed through specific destinations to keep it more secure. Because of the way that Ethernet networks work, tapping these lines is relatively easy, so sophisticated security options have become available over the years that make it possible for data to travel with the great degree of efficiency that an Ethernet network affords without compromising security to the point that the technology is impractical.

 

Which Role do Ethernet Transformers Play in an Ethernet?

Ethernet transformers play different roles in different types of Ethernet networks. In a 10BaseT Ethernet network, the transformer essentially functions as a low pass filter. This helps to deal with noise and to ensure the proper wave form.

In a 100 Mb Ethernet, the transformer functions in a way that is more identifiable with the role that transformers normally play. They are used to match impedance in the network. They are also used for isolation. Most of these transformers are 100 ohms at 1:1 impedance.

 

How Does an Ethernet Transformer work?

And Ethernet transformer can either match impedance in a network or they can be utilized to function as filters, keeping signal within acceptable parameters.

 

What is the Number of Output Ports?

This number describes the number of ports available on the Internet transformer that can be utilized as outputs on the network.

 

What Does Insertion Loss Mean?

Insertion loss is measured in decibels and is described as a maximum value on specification sheets. It describes exactly what the name implies, the amount of signal power that is lost as a result of inserting the device into the network. Obviously, lower numbers are generally favorable.

 

What Does the Maximum and Minimum Operating Frequency Define?

The maximum and minimum operating frequency describe those frequencies in which the Ethernet transformer must operate to function as expected. Exceeding these limits may result in errors or other issues.

 

What Does the Maximum and Minimum Temperature Define?

Like all other electronic components, Ethernet transformers have a safe operating temperature range in which they must be used. Exceeding this can result in equipment failure, poor performance or other issues with the transformer.