What is Ethernet?

Rene DescartesEthernet is a type of network cabling and signaling specifications developed by Xerox in the late 1970. While Internet is a global network, Ethernet is a local area network (LAN). No computer should be an island. With Ethernet, file sharing and printer sharing among machines became possible. The term "ether" was coined by Greek philosopher Aristotle to describe the "divine element" in the heaven. In the 17th century, French philosopher and mathematician Rene Descartes theorized that the universe has no void; all space, including the heaven and the earth, is filled with ether, which is composed of very fine particles. In short, "ether" is said to be a kind of substance that exists everywhere. Although this is a misconception, network developers still adopted the term "ether" and therefore "Ethernet" means "a network of everywhere."

How does it work?

Ethernet uses a communication concept called datagrams to get messages across the network. The Ethernet datagrams take the form of self-contained packets of information. These packages have fields containing information about the data, their origin, their destination and the type of data. The data field in each package can contain up to 1500 bytes. Take mailing as a metaphor. An Ethernet package is not just a letter. It is also provided with the sender address, the receiver address, the stamp indicating what the package's contents are.

What are the number, and the words "Base" and "T"?

There are several standards of Ethernet, such as 1000BaseT, 10GBaseT...etc. The number stands for signaling speed:  "1000" is 1000 mega bit per second. However, it is important to point out that this number indicates the "ideal" situation. The actual speed might be slower. "Base" means Baseband, which uses a single carrier frequency so that all devices connected to the network can hear all transmissions. "T" stands for twisted pair cable.

Half-duplex vs. full-duplex

Ethernet suffers from collision when it is running in half-duplex mode. What is half-duplex? CB radio is a typical example of half-duplex. When using a CB radio, you can either send a message or receive a message at one time. When two or more computers attempt to send data at the same time, a collision occurs. Nevertheless, switches make it possible to run Ethernet in full-duplex mode. In this mode, two computers establish a point-to-point connection in full-duplex and thus collisions are avoided.

Advantages of Ethernet

Upgradability: There are several other superfast network protocols. Some of them must use Fiber optics and thus its price is much greater than that of Ethernet. But some superfast networks, such as 100G BaseT Ethernet, are based upon more affordable technologies. Therefore, installing BaseT Ethernet may make the upgrade to a faster network easier in the future.

Simplicity of installation: In the past IBM Token Ring was a rival of Ethernet, but like IBM's OS/2 lost the OS war to Microsoft Windows, Token Ring also lost the network war. Although it was capable of transmitting signals at 16 million bit per second, which was faster than 10BaseT Ethernet (10 megabit per second), it was very difficult to configure. Networking expert Frank Derfler said, "The Token Ring is to networks what the Boeing 747 is to airplanes. It makes strange noises and requires special handling."

Installation of Ethernet is easier and less expensive than other network protocols. It offers efficient ways to connect across Mac, PC, Linux, Unix workstations, IBM mainframe, and many other kinds of computer systems. Therefore, Ethernet is more popular than other network protocols.

Connectivity to backbone: As mentioned before, Ethernet is a local area network protocol for different sub-networks of a company or a campus. For networking the entire company or campus, it needs a backbone network protocol. A backbone network is like a fish's backbone, to where every smaller bone (sub-network) is connected. Ethernet has an advantage in connectivity to backbone because other LAN protocols lag behind in backbone innovations. For instance, the only way to upgrade Token Ring backbone was to move to Asynchronous Transfer Mode (ATM). In contrast, Ethernet have several choices such as Gigabit Ethernet, ATM, and routing switches.


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