Ethernet is a communications standard. It was developed for network computers and other devices in the early 80s. In its early days, it was used as LAN (Local Area Network). That is, building, house, workplace, etc. It is used to connect many devices in the environment and to share and store information and data between these devices. Ethernet is a wired system. This system first started with coaxial cable and now continues with twisted pair copper cable and fiber optic cable. Ethernet 802.3 was approved as a standard by (IEEE) in 1983. It can be defined as the physical layer and the data link layer (MAC), which are defined as the first two layers in the OSI model.
The physical layer consists of two subcomponents. These are wiring and devices. If we look at the cabling section, coaxial cable is generally not available except in old installations. Currently, twisted pair wire and fiber optic cable are used. The most common is twisted pair cable. There are four most commonly used types of these cables. These are CAT5/5e, CAT6/6a, CAT7.
CAT5/5e has a transmission speed of 100Mbps, CAT6/ 1Gbps, CAT6a and 7 10Gbps. RJ-45 connector is used in Ethernet twisted pair cable. Unidirectional, bidirectional and simultaneous bidirectional transmission can be achieved in twisted pair cable. It is necessary to use two pairs of wires for the same two-way transmission. Fiber optic cable uses glass or plastic optical fiber as the channel to transmit data. These cables enabled Ethernet to travel longer distances at higher speeds. Depending on the application requirement, SFP(Small Form Pluggable) and SC(Subscriber Connector) are used.
Ethernet devices consist of computers. Any device with an internal or external NIC (Network Interface Card) can be connected to the network (Example: Printer). When we connect multiple devices, switches and routers manage the network.
Gateways or Bridges are used to connect multiple Ethernet networks. Gateways connect two dissimilar networks, while Bridges connect two similar networks. This way only one network is visible.
The data link layer can be divided into two parts: LLC(Logical Link Control) and MAC(Media Access Control). For transmission over Ethernet, LLC creates paths for data. MAC uses hardware addresses assigned to network interface cards. All this is to identify the device and show the transmission source and destination. Ethernet transmits data packets at the data link layer using the algorithm called CSMA/CD (carrier sensing multiple access/collision detection). This algorithm first checks the network traffic. It then sends the first bit of data. If there is no problem, it continues to test for conflicts and sends other bits. Finally, if we compare a star topology with a bus topology, there will be fewer collisions in the star topology. Because in bus topology, all devices use the same bus.