What is Ethernet? The standards, explained

A close-up shot of Ethernet cables plugged into a router
(Image credit: Shutterstock)

Knowing what Ethernet technology is can be crucial to understanding the ways devices such as computers are connected to the internet. The technology, and the standards underpinning it, are essential to the world of networking.

Even though Ethernet may be complex, more so for those not familiar with the ways of the world of networking, comprehending how Ethernet connections work is crucial to maintaining a job in IT. Moreover, taking this information on board offers a lot that can be implemented to solve problems relating to faulty networks.

Getting one’s head around Ethernet at a higher level involves coming to terms with a number of standards, unpacked below. As with many such standards in IT, these can be hard to unpick especially as new iterations have shared similar names while introducing significant improvements to the technology.

A perfect example of this is USB Type C. After the release of the USB 3.2, a full rebrand was launched that saw the slower USB 3.0 and 3.1 connection redefined into USB 3.2 Gen 1 and USB 3.2 Gen 2. Meanwhile, USB 3.2 was renamed to USB 3.2 2x2.

The TCP/IP protocol technology is the key theory behind Ethernet, first proposed by Robert Metcalf in his PhD thesis in the 70s. This technology then went on to be standardised in a patent by Xerox, which employed him and cited Butler Lampson, Chuck Thacker, and David Broggs as co-inventors. This was the beginning of the technology, led by pioneering inventors.

But because nothing of this sort had ever existed, there were no existing standards or foundations on which to base the framework for Ethernet technology. The documentation had to be written from scratch and as a result, the paperwork surrounding Ethernet is lengthy.

The history of Ethernet development

When Ethernet was first devised, the technology comprised coaxial cables of various grades which one was expected to pierce with a long spike. They were referred to more commonly as drop leads or patch leads, which were large and stiff 15-pin connectors. This was quickly revised, with a breakthrough coming in the form of a more slender coaxial, with twist-link barrel connectors for joints and wall sockets.

At such an early stage there was no need to tweak any elements of the software or recompile programmes to transition from one wiring standard to the other, which some argue come from a wider-cast standard of work around the seven-layer OSI transport model. Although this could very much be the case, it doesn't take into account a basic Ethernet fundamental from one of the earliest standards. This is because Ethernet actually doesn't demand any specified layout of a packet.

The implementation's openness allowed one to expand the standard to a high degree from the beginning. It's a particular concern for businesses, with this becoming a key reason your IT expenditure could potentially balloon. With plenty of buildings floor-wired to service users with Ethernet via unshielded twisted pair (UTP), it can be a real benefit but also something of a drawback. This is because it's easy to install a wiring plan that turns out to be disabled by standards as opposed to enabled by them.

This is because the success of UTP as a business networking format has been so immense that early and quite rigorous adherence to standards has been left in the dust. Gone are the days when every single piece of wire in a whole installation would be accompanied by a time-consuming and exhaustive signal quality report, or indeed when you would see qualified technicians laying cable in carefully routed trays.

In some cases, you'll find straightforward electricians putting up Cat5E cables with cable retaining nails, neatly smashing into the solid conductors inside the UTP enclosure - these looked fine while machines were connecting at 10Mbit/sec but utterly refuse to function with gigabit Ethernet over UTP requirements. The new standard requires all eight conductors within the cable sheath to function perfectly to specification, which rapidly exposes hasty or ignorant installation practices.

Ethernet standards explained


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PresentationThick coax
StatusOfficially phased out in 2003 - heavily superseded
Effective range500m depending on number of drilled holes
UptakeEarly years only but quite widespread


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PresentationThin coax, 50 ohm, barrel twist connector
StatusPhased out in 2011 - switchless and therefore all about collisions
Effective rangeVaries according to installation
UptakeVery widespread through 1980s. Pivotal tech for Novell LAN cards
LifecycleStill live in a few places but ripe for replacement


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PresentationUnshielded twisted pair, 8 conductors. Hub-centred
StatusAlmost universal - used by faster standards too
Effective range100m from switch or repeater
UptakeKey network enabler for most of the planet


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PresentationOptical fibre (2 strands)
StatusSometimes found in early campus wiring, telecoms et cetera - 2km range remains useful, and effort of laying cables may be impossible to repeat
Effective range2km
UptakeSmall, as fibre is expensive and difficult to maintain


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PresentationUnshielded twisted pair, 8 conductors, hub-centred
StatusAlmost universal - desktop data transfer fits perfectly
Effective range100m over copper
UptakeCat5E cabling is most common (though other variations may be found)


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PresentationUnshielded twisted pair, 8 conductors, switch-centred
StatusServer rooms, switch links, desktops - not all cable installs support Gbit speed well
Effective range100m over copper
UptakeStill not as widespread as it could be


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PresentationCat6A twisted-pair, switch-centered
StatusMostly server rooms - different wiring pays back with higher speeds
Effective range25m to 400m according to installation
UptakeSlow, as many find it hard to realise the speed benefits

25, 40 & 100BASE-T

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PresentationCat8 cabling at a minimum
StatusServer data centres, storage arrays - all are subsets of the 100Gbit project
Effective range30m (single lane) up to 30km (4-lane fibre)
UptakeLow, as deployment is complex and specialised
LifecycleLikely to be long but only in specialised deployments

The future of ethernet

It's easy to assume that the ramp of both speed and sustained capability is likely to keep on increasing, with the road to 10 gigabit broadband leading 10 gigabit Ethernet to be implemented to function over common Cat5E. This move has been accompanied by a bit of a first: dropping some previously universal and reliable standard features.

Those who follow the speed race assiduously will be sneering. The leading edge of both standards and hardware development is currently hovering at the 100Gbit/sec mark: Why on earth would anyone refuse to go faster?

This is because faster Ethernet is difficult to install, and can be costly. Before gigabit Ethernet was developed for UTP copper cables, it was readily available so long as you were ready for optical fibre cable in a business environment. Fibre's main advantage in this context has been that it is largely immune to lazy implementation: fibres have to be handled carefully, routed sensitively, and terminated cleanly with surgical, submicroscopic precision.


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You can run an Ethernet fibre for 70km, and this is a satisfying upgrade from the usual UTP limit of 100 metres but involves some considerable expenditure. It also requires engineers to work outside their usual sphere.

A lot of the fastest platforms for establishing connections via Ethernet such as the 40Gbit/sec standard used in supercomputers and data centres use bundled fibres, which are incredibly complex to assemble.

It really is important not to fret about lost performance opportunities in business Ethernet deployments: For every user who thinks that high throughput is the same thing as low latency, there are justifications for keeping desktop traffic speeds down. It's green, for example, as modern switches adopt another standard which turns down the power when traffic is light.

It's also not really necessary if you have shifted to a cloud or Thin Client computing model. A sensible Cloud or Thin Client session is very bitty (that is, it ships data in very small chunks), and quite low volume. Imagine a gigabit Ethernet session carrying typing keystrokes, each one within a surrounding padded-out 512-byte minimum packet size. That padded-out behaviour doesn't apply at 100Mbit/sec, making the slower session faster.

Only by looking at the standards and understanding their intentions can you get a rational business justification for going faster, or indeed slower depending on one's goals.

Why use Ethernet?

Most devices today support wireless connectivity, and as such one may question the validity of Ethernet. However, due to its core function in business networks and reliability over wireless connectivity, there are a number of reasons why Ethernet is better than Wi-Fi. It's clear that Ethernet is here to stay for the foreseeable future.

Business Wi-Fi networks can be incredibly difficult to roll out and maintain, and though firms like Nokia and Kyndryl continue their partnership to develop private LTE and 5G networks for industry use, wireless networks still have limitations. For example, 5G and 5G mmWave can struggle with tough geometry such as concrete and metal, which can make establishing a consistent network connection troublesome across a large site or obstructed work environment.

Even as 6G begins to appear on the horizon, businesses retain Ethernet connections as a proven backbone for stable, fast internet. That’s not to say that it’s inherently better than wireless connectivity - Ethernet isn’t very useful for keeping autonomous Internet of Things (IoT) devices, for example - but it certainly retains a strong set of business use cases.

Factoring in advancements such as Wi-Fi 6, and 5G mmWave which form the backbone of multi-gigabit wireless connections, businesses now have a strong choice when it comes to high throughput connections. But Ethernet still remains top of the pile in terms of maximum speeds, capable of delivering 100 Gbit/sec at its maximum released standard.

Clare Hopping
Freelance writer

Clare is the founder of Blue Cactus Digital, a digital marketing company that helps ethical and sustainability-focused businesses grow their customer base.

Prior to becoming a marketer, Clare was a journalist, working at a range of mobile device-focused outlets including Know Your Mobile before moving into freelance life.

As a freelance writer, she drew on her expertise in mobility to write features and guides for ITPro, as well as regularly writing news stories on a wide range of topics.