History Ethernet

Today, companies consider using Ethernet as their wired local area network. But before that, things weren't like that. Steven Vaughan-Nichols has been tracking the history of Ethernet, and its competitors in the area of ​​its previous network protocols.

Today, we obviously use Ethernet. Just plug the plug into the wall outlet or turn on the switch to have a network to use.

Ethernet in the 1960s and 1970s

In the 1960s and 1970s, the network was considered a special technology and not very popular. But then Robert "Bob" Metcalfe was asked to create a local area network (LAN) for Xerox's Palo Alto Research Center (PARC). And Ethernet, his creativity, has changed everything.

Back in 1972, Metcalfe, David Boggs and other members of the PARC team, assigned to the problem of networking, never thought of changing the world. They just want to activate Xerox Alto of PARC - the first personal workstation with a graphical user interface and considered the modern 'ancestor' of Mac - to connect and use the world's first laser printer. , Scanned Laser Output Terminal.

That is not an easy problem. The network must connect hundreds of computers at once and fast enough to control laser printers.

Metcalfe did not try to create the network from all that is available. He used previous works to inspire him. In particular, Metcalfe found Norman Abramson's 1970 article about ALOHAnet package radio system. ALOHAnet is used for data connections in the Hawaiian Islands. Unlike ARPANET, in which communication is based on dedicated connections, ALOHAnet uses UHF frequencies to share network transmission.

ALOHAnet solved an important problem: How does this technology work when two radio signals are broadcast at the same time and create a 'collision' between the two packages? The nodes will replay the "lost in ether" packets after waiting for a random amount of time. Although this 'primitive' form of collision avoidance works relatively well, Abramson's original design shows that ALOHAnet will reach maximum traffic when only 17% of its maximum performance is used. its power.

Metcalfe studied this problem at the school, where he discovered that, with algorithms that put packets into the right queue, 90% of the potential traffic could be achieved. His work has become the basis of Ethernet media (Control Access Control - MAC) rules: Enables multiple access with collision detection (Carrier Sense Multiple Access with Collision Detect - CSMA /CD).

However, for PARC, a wireless solution is not practical. Instead, Metcalfe switches to coaxial cable. But instead of calling it CoaxNet or attaching to the original name, the Alto Aloha network, Metcalfe borrowed an 'obsolete' phrase from the 19th century scientific history: Ether. In 19th century physics, "luminiferous ether" is the term used for the medium through which light travels.

Metcalfe explained in a 2009 interview as follows: 'The whole concept of a comprehensive environment (omnipresent), completely passive to transmit electromagnetic waves does not exist. It is a fantasy. But when David [Boggs] and I were building a network at PARC, we planned to run cables up and down in every corridor to really create a comprehensive, completely passive environment for wave propagation. electromagnetic. And in this case the data packet. "The first nodes on Ethernet were named Michelson and Morley, after the scientists discovered the non-existence of the ether.

On May 22, 1973, Metcalfe wrote a memorandum for PARC management to explain how Ethernet works. Coaxial cables are located in the corridor of PARC, and the first computers were attached to this bus-type network on November 11, 1973. The new network boasts a speed of 3 megabits per second (Mbps) and immediately become a phenomenon at that time.

In the next few years, Ethernet is still a closed, internal system. Then, in 1976, Metcalfe and Boggs published an article, "Ethernet: Distributing switching packets for local computer networks." Xerox patented technology, but unlike many modern companies, Xerox shared the idea of ​​Ethernet for others.

Metcalfe, who left Xerox to found 3Com in 1979, came up with this idea, then persuaded DEC, Intel and Xerox to agree to commercialize Ethernet. DIX Alliance, has done a great job of this. DIX hopes to make Ethernet a standard, but the IEEE 802 committee does not agree with this. It took many years, but on June 23, 1983, the IEEE 802.3 committee finally approved Ethernet as the standard. That is, CSMA / CD of Ethernet has been approved. There are some minor differences between 802.3 and Ethernet II (aka DIX 2.0).

To date, Ethernet has reached speeds of 10 Mbps and is becoming widely available. Partly, that's because physical design has improved. The first Ethernet uses 9.5 mm coaxial cable, also known as ThickNet. To attach the device to this 10Base5 physical media, you have to drill a small hole in the cable itself to place the "hose", so it is very difficult to deploy.

The so-called Thinnet (10Base2) means using cable-like cable TV, RG-58A / U. This makes network cable placement much easier. In addition, you can now easily connect your computer to the network with a T connector. But 10Base2 has a big problem: If the cable is interrupted somewhere, the entire network segment will be broken. . In a large office, monitoring a broken connection somewhere in the entire network is an extremely difficult task.

Ethernet in the 1980s

By the 1980s, both 10Base5 and 10Base2 began to be replaced with twisted-pair (UTP) cables without a cover. This technology (10BaseT) and its many "descendants" (like 100Base-TX and 1000Base-T) are what most of us use today.

In the early 80s, Ethernet faced fierce competition from two other networking technologies: Bus token, won by General Motors for its factory network, and IBM's famous Token Ring.

Use bandwidth of Token Ring more effectively. Larger package size - Token Ring at 4 Mbps has a packet size of 4,550 bytes, many times larger than 1,514 bytes of 10 Mbps Ethernet - making it significantly faster than Ethernet.

Another challenge of Ethernet is Attached Resource Computer Network (ARCNET). Originally created in the 1970s as an exclusive network by Datapoint Corp., like Ethernet and Token Ring, ARCNET officially appeared in the 1980s. ARCNET is also a network protocol based on token, but it uses a bus rather than a ring structure. In the late 1970s, the structure was based on its simple bus and clocked at 2.5 Mbps, making it more attractive.

Some things make sure that Ethernet will win. First, as Urs Von Burg described in his book, The Triumph of Ethernet, DEC soon decided to support Ethernet. This has helped significantly to network technology during IEEE standardization.

Ethernet is also a much more open standard. IBM's Token Ring has been opened in theory, but Metcalfe has said that in fact, non-IBM Token Ring devices rarely work with IBM computers. Ethernet soon had more than 20 companies supporting it. Products based on its cost-competitive standards work together. (For networks in the late 1980s, most of us tend to choose a hardware vendor for Ethernet and stick with that brand.)

Ethernet in the 1990s

ARCNET, only increased to 20 Mbps in 1992 with ARCNET Plus, slower than in the late 1980s and early 1990s. Since many developers worked on it, Ethernet also quickly narrowed the public gap. technology with Token Ring.

In particular, 10BaseT, became an IEEE standard in 1990, allowing the use of hubs and switches. This freed Ethernet from the bulky bus structure and provides the flexibility of the star-shaped structure. This change has made it easier for network administrators to manage their networks and to give users more flexibility in placing their personal computers. In the early 1990s, 10BaseT Ethernet was also much cheaper than Token Ring.

The final move to completely defeat the Token Ring is 100 Mbps Ethernet and Ethernet switching. Today, it is possible to have old Token Ring networks running, but they are just historical curiosities. At the same time, 802.11n and other Wi-Fi technologies have become extremely popular. But to provide network connectivity for Wi-Fi access points, Ethernet will always play an important role.

See more:

1. Network wire history
2. Ethernet cable and how it works
3. How is wired (Ethernet) better than wireless (Wi-Fi)?