What is Ethernet?

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Have you heard of IEEE 802.3? It has a long history and has to do with our topic today, Ethernet.

Ethernet is a communication standard that was developed in the early ’80s to network computers and other devices in a local environment such as a home or a building.

This local environment is defined as a LAN (Local Area Network) and it connects multiple devices so that they can create, store and share information with others in the location.

Ethernet is a wired system that started with using coaxial cable and has successfully progressed to now using twisted pair copper wiring and fiber optic wiring.

Let’s break for a trivia question. Who invented twisted pair wiring?
Alexander Graham Bell invented twisted pair wiring in 1881.

In 1983, Ethernet was standardized into the standard IEEE 802.3 by the Institute of Electrical and Electronic Engineers (IEEE).

This standard defined the physical layer and the MAC (media access control) portion of the data link layer of wired Ethernet.
These two layers are defined as the first two layers in the OSI (Open Systems Interconnection) model
The “physical” layer consists of the following components: Cabling and Devices.

First, let’s take a look at Ethernet Cabling;
As stated previously, Ethernet cables come as coaxial cable, which is not very common except in older installations, twisted pair, and fiber optic.

The most common cable is twisted pair cables, with the latest being Category 6 with speeds up to 1 Gbps and Cat6a and Cat 7 with speeds up to 10 Gbps.

Category 5 and 5e cables are both still used in many existing applications but handle the lower speeds between 10 Mbps to 100 Mbps but are more susceptible to noise.

The Ethernet twisted pair utilizes RJ-45 eight-pin connectors at either end of the cable that is pinned for transmitting and receiving data in either half or full-duplex mode.

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[handsome-soup]

Wow you liked all the comments even after 1 year

[flamingmoose]

Thank you. I'm trying to get certified to work in networking and using a textbook alone has been rough, but with your videos and visuals everything comes together and makes way more sense.

[radishpineapple]

A couple things:
1. As others have said, cat 5e can be used for 1 Gbps speeds.
2. CSMA/CD is no longer needed for full-duplex switched networks, each link is isolated and collisions are eliminated. Indeed, half-duplex links are no longer specified in 1 Gbps Ethernet, and aren't allowed at all in 10 Gbps. 802.11 Wifi does have collision issues due to its half-duplex nature, but it uses a related CSMA/Collision Avoidance method instead.

[timothykearns]

Bell invented twisted-pair wiring to counteract capacitance found in non-twisted pairs. "Loading" coils were also added at pre-determined distances. XL and XC cancel themselves out in tuned (resonant) circuits, making the "load" purely resistive. Telephone lines weren't "resonant", but every little bit and XC are inductive and capacitive reactance, respectively. If I've made any errors, please retired almost 9-years ago, and my memory of such things is flagging.

[waynezahra]

Hey Mr, Im learning about networking. Even though I understood what I was reading, you’ve made of far easier for me to have a mental image in my mind and also to give a clear understanding how Ethernet works. Thank you kindly. Now I must watch your other videos on networking. Wishing you a great day 🙏🏻

[Redfield-hknn]

this is one of the best videos I have ever seen on youtube thanks for that!!!! Way to good!!!!

[Blades-fmck]

These great videos are so clearly explained. Clear speech, no distracting background music & excellent graphics.

[laszlozoltan]

I wish I had seen this video ages ago before tearing my hair out for days while setting up my asus router- not many home consumers have had the benefit of any technical training, while many troubleshooting links proved to be information-runarounds.
good job on clarity

[fujiwxrx]

This is very useful for my polytechnic engineering research work. Thanks alot guys!

[emmanuelsanusi]

Thank you Realpar team. You're really making impact More strength !!!!

[varunk]

Me watching this video after 4 years of communication engineering.

I regret my choices in college.

[James_Knott]

As for the points about this presentation, Gigabit Ethernet was designed for use on plain CAT 5 cable and predates 5e, which is just CAT 5 with tighter specs. So, CAT 5 will work fine at 1 Gb, for up to 100M (330"). Also, CSMA/CD is used only for half duplex, as you'd find with coax or hubs. It is not used with full duplex, where collisions are not possible. With CSMA/CD, collisions are normal within the first 512 bits and will trigger re-transmission, with random back off, to avoid additional collisions.

There are 3 "official" versions of Ethernet, which followed the original experimental version which ran at 2.91 Mb and had an 8 bit MAC address. The 3 versions are the original DIX 1.0, DIX 2.0 and 802.3. The main difference between 1.0 and 2.0 is the first field was changed from "Type" to "Ethertype/Length" to accommodate 802.3. If the contents of this field is 1500 or less, it's 802.3 or DIX 2, if above 1536. IP normally uses DIX 2. The old Netware IPX used 802.3.

There is some more info on Wikipedia:

And here's a link to the original DIX 1.0 "Blue Book" spec:

Here's an excellent reference:

[MaNemUmar]

Loving the Diversified approach to industrial automation technology !

[TrionityIr]

As an electrical engineer trying to learn networking for my job, this is fantastic. Thanks

[cyrox]

winderful as usual, very informative and deeply explained, thank you

[yousefhesham]

thank you very much
ccna i have learned and you learned me so much
from EGYPT

[LindeSir]

Basically Cat5e is 4 pair (8 copper wires) White, White Blue, White, White Orange, White, White Green, White White Brown. This is your standard Cat 5e layout for DVO jacks and how they would be made on ends. Sometimes in the world too you could see the White, White Green and White, White Orange swapped around. That is to give Power Over Ethernet for devices that are using a PoE injector to get power like an outdoor satellite in some instances

[ankitaboruah]

This video is so great! Very informative and the diagrams help in visualizing the things in our minds.

[sprugner]

Very well explained, thank you for all the work you put into this video. 👍

[melquiadesdelgadoramirez]

That´s why I recommend your videos, they really leave upstanding information on us. Keep doing your great job!!!