What is Ethernet?
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0:02 Have you heard of IEEE 802.3? It has a long history and has to do with our topic today, Ethernet.
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0:44 Ethernet is a communication standard that was developed in the early ’80s to network computers and other devices
0:51 in a local environment such as a home or a building. This local environment is defined as a LAN (Local Area Network)
1:01 and it connects multiple devices so that they can create, store and share information with others in the location.
1:10 Ethernet is a wired system that started with using coaxial cable
1:14 and has successfully progressed to now using twisted pair copper wiring and fiber optic wiring.
1:22 Let’s break for a trivia question. Who invented twisted pair wiring?
1:29 Alexander Graham Bell invented twisted pair wiring in 1881. In 1983, Ethernet was standardized
1:38 into the standard IEEE 802.3 by the Institute of Electrical and Electronic Engineers (IEEE).
1:48 This standard defined the physical layer and the MAC (media access control) portion of the data link layer of wired Ethernet.
1:57 These two layers are defined as the first two layers in the OSI (Open Systems Interconnection) model
2:06 The “physical” layer consists of the following components: Cabling and Devices.
2:14 First, let’s take a look at Ethernet Cabling; As stated previously, Ethernet cables come as coaxial cable,
2:23 which is not very common except in older installations, twisted pair, and fiber optic.
2:31 The most common cable is twisted pair cables, with the latest being Category 6 with speeds up to 1 Gbps
2:39 and Cat6a and Cat 7 with speeds up to 10 Gbps. Category 5 and 5e cables are both still used in many existing applications
2:53 but handle the lower speeds between 10 Mbps to 100 Mbps but are more susceptible to noise.
3:04 The Ethernet twisted pair utilizes RJ-45 eight-pin connectors at either end of the cable that is pinned for transmitting
3:13 and receiving data in either half or full-duplex mode. Half-duplex transmits data in one direction at a time
3:22 while “full-duplex” allows data to be transmitted in both directions at the same time.
3:29 Full-duplex in Ethernet can be achieved by using two pairs of wires to allow data to travel both directions simultaneously.
3:39 Fiber optic cable uses glass or plastic optical fiber as a conduit for light pulses to transmit data.
3:48 It has allowed Ethernet to travel farther distances at higher speeds. Fiber optic cables use several different types of connectors
3:58 that vary depending on your application needs. Some of the different types are SFP
4:05 (Small Form Pluggable or Small Factor Pluggable) and SC (Subscriber Connector, also known as Square Connector or Standard Connector).
4:19 In order to use fiber optic in an Ethernet network that utilizes twisted pair Ethernet cabling,
4:25 you need to use an Ethernet to fiber converter that will allow your network to take advantage of the higher speeds of fiber optic
4:33 and lengthen the distance that the Ethernet network can reach. How about the Ethernet devices?
4:42 Ethernet devices are consist of computers, printers or any device which either have an internal NIC
4:49 (Network Interface Card) or an external one that is USB or PCI based.
4:57 “Switches” and “Routers” that act as the director of the network and connect multiple computers
5:03 or even networks together to enable communication between all the different devices.
5:11 “Gateways” or “Bridges” are used to connect multiple Ethernet networks together and allow communication across them.
5:20 Gateways connect two dissimilar networks together while a bridge connects two similar networks together
5:26 so that you only see one network. Now that we have discussed the basic physical components of Ethernet,
5:35 let’s move into the second layer of the OSI model, the “data link” layer. The data link layer can be split into two sections;
5:45 the Logical Link Control (LLC) and the Media Access Control (MAC).
5:54 The Logical Link Control establishes paths for data on the Ethernet to transmit between devices.
6:01 The Media Access Control uses hardware addresses that are assigned to Network Interface Cards (NIC)
6:08 to identify a specific computer or device to show the source and destination of data transmissions.
6:17 Ethernet transmits data packets in this data link layer by using an algorithm called CSMA/CD
6:25 (Carrier Sense Multiple Access with Collision Detection). CSMA/CD is used as a standard for Ethernet
6:34 to reduce data collisions and increase successful data transmission. The algorithm first checks to see if there is traffic on the network.
6:44 If it does not find any, it will send out the first bit of information to see if a collision will occur.
6:51 If this first bit is successful, then it will send out the other bits while still testing for collisions.
6:58 If a collision occurs, the algorithm calculates a waiting time and then starts the process all over again
7:05 until the full transmission is complete. When you use the faster Ethernets in full-duplex modes
7:14 and incorporate switches, then you are utilizing a star topology
7:18 between the switch ports and the devices. This allows for more direct transmission paths and fewer collisions
7:25 as compared to a bus topology where all devices share the same paths. Ethernet capabilities are quickly changing with new technologies emerging every day.
7:38 And while we are currently on the brink of successfully moving into speeds higher than the current 1 Gbps with 10 Gbps emerging over the last few years,
7:48 these new Ethernet technologies will be costly. Also, your possibilities for the information world
7:58 can seem endless when you connect this Ethernet local area network to the internet to create a very large WAN (Wide Area Network).
8:08 But that is a story for another day. All in all, Ethernet is popular
8:14 because it strikes a good balance between speed, cost, and ease of installation.
8:21 These benefits, combined with wide acceptance in the computer marketplace and the ability to support virtually all popular network protocols.
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