Feature

Ethernet's fast expanding network

Ethernet is no longer the preserve of office Lans, writes Nick Langley.

What is it?
Ethernet is still the most widely deployed local area network technology. Fast Ethernet and Gigabit Ethernet raised its capacity from 10Mbits to 100Mbits and then 1000Mbits. Suppliers are now beginning to ship 10 Gigabit Ethernet, delivering 10,000mbps. There is also Wireless Ethernet.

Originally Ethernet was purely a Lan, restricted to a few hundred metres. It can now be used in wide area networks and backbones.

Ethernet is a packet-switched technology - that is, each packet or frame of data contains the address of its destination. Ethernet supports Internet Protocol and most other higher-level protocols.

Where did it originate?
Ethernet was developed at Xerox Parc by Bob Metcalfe and David Boggs in 1973. Metcalfe was looking for a way to connect Xerox's Alto PC to a printer and came up with a cabling infrastructure that enabled multiple devices to be connected - and new devices added - on a single wire.

In 1976, Metcalfe published Ethernet: Distributed Packet-Switching For Local Computer Networks. Metcalfe left Xerox in 1979 to form 3Com.

Xerox passed control of Ethernet to the Institute of Electrical and Electronics Engineers' 802 committee, which was set up to establish standards for Lan technologies. The first independent Ethernet standard appeared in 1980. The Fast Ethernet standard was approved in 1995, and Gigabit Ethernet in 1998.

What is it for?
Once mostly found in office networks, Ethernet's applications now include the National Grid for Learning, which uses Wireless Ethernet to link schools in remote areas, metropolitan area networks, and network-attached storage.

What makes it special?
Partly because Ethernet was an industry standard, it was adopted more widely than proprietary rivals such as IBM's Token Ring. As each faster version of Ethernet has emerged, it has maintained compatibility with earlier versions. Gigabit Ethernet employs the same protocol (CSMA/CD), frame format and frame size as 10BaseT and Fast Ethernet.

How difficult is it?
Designing Ethernet networks is an art, since they get very congested above 50% capacity. You will need to know about the repeaters, hubs and bridges that enable larger networks to be built. But since all versions of Ethernet function identically regardless of speed, you should be able to work with any version once you have been trained.

However, that is akin to saying you can move from supervising cart traffic on country lanes to designing motorways. You may have to train a bit more for Gigabit Ethernet.

Where is it used?
Having long dominated the commercial and academic Lan spaces, Ethernet may be moving to the domestic user.

Don't confuse. . .
Parcelforce with a packet-switching network.

What does it run on?
The infrastructure may be thick or thin coaxial cable, fibre optic, twisted pair or wireless.

Few people know that. . .
The second generation, Ethernet II, was sometimes called Dix, after its sponsors, Digital, Intel and Xerox. Traditional jazz lovers might have enjoyed Dix Lan bandwidth.

What is coming up?
Ethernet in the first mile of the telecoms infrastructure, which will enable the deployment of Ethernet broadband services in the "local loop" - the bit that joins homes and offices to the rest of the public subscriber network, forming a bandwidth bottleneck we have all suffered from.

Rates of pay
Those with Ethernet skills can earn £20,000 in support, rising to £40,000+ in network management, capacity planning and design.

Training
Ethernet training is widely offered by independent training organisations and suppliers such as Cisco. The brave, foolhardy, or hard-up among you could try free internet tutorials ( www.tutorgig.com), or read Charles Spurgeon's Ethernet: A Definitive Guide, published by O'Reilly.

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This was first published in January 2003

 

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