We are most used to WiFi nowadays due to the convenience provided by them. But, for businesses and data centers the traditional cables are being used as they are more reliable, fast, and secured. Ethernet is a technology that connects wired Local Area Networks (LAN) and enables the device to communicate with each other. One of the primary purposes of this layer is to essentially abstract away the need for any other layers to care about the physical layer and what hardware is in use. By dumping this responsibility on the data link layer, the Internet, transport, and application layers can all operate the same no matter how the device they’re running on is connected. So, for example, our web browser doesn’t need to know if it’s running on a device connected via a twisted pair or a wireless connection. It just needs the underlying layers to send and receive data for them.
Local Area Network (LAN): It is a computer network that connects the devices that are in a limited area such as college campuses, companies, etc.
Ethernet describes how networking devices can possibly transmit data over the same network and can process the received information. We know about networking devices like hubs and switches that are used inorder to avoid the collision domain. But in the earlier days, when Ethernet is not invented, the data that is transmitted will take a change in the end result due to the collisions in the electrical signals. Ethernet solved this problem using a technique known as CSMA/CD.
Carrier Sense Multiple Access/ Collision Detection (CSMA/CD): It checks when the device is free and communication channels are clear to transmit the data. If two computers are transmitting the data at the same time, CSMA/CD detects this and stops sending data. Then each device involved in the collision domain waits at random intervals of time to transmit their data. If there is no data being transmitted on the network segment, then the nodes will be free to transmit the data. In this way, collision is prevented. If the network segment is a collision domain, then the information sent by a single device will be received by all the other devices on the network. So, there should be a method to transmit the data to the device it is meant for. Here’s where MAC comes into play.
Media Access Control (MAC): A MAC address is a hardware identification number (unique) that is used to identify a device over a network. It is a 48-bit number grouped into six groups of two hexadecimal numbers. Along with the numbers from 0-9, the MAC address employs A-F to represent 10-15. The other way to reference each group of numbers in a MAC address is an octet. An octet, in computer networking, is any number that can be represented by 8 bits. In this case, two hexadecimal digits can represent the same numbers that 8 bits can.
The first three octets of a MAC address are known as the organizationally unique identifier or OUI. These are assigned to individual hardware manufacturers by the IEEE or the Institute of Electrical and Electronics Engineers. Using this, we can easily identify the manufacturer of the device. The last three octets of MAC address can be assigned in any way that the manufacturer would like with the condition that they should assign all MAC addresses in such a way that they are globally unique. Ethernet uses MAC addresses to ensure that the data it sends has both an address for the machine that sent the transmission, as well as the one that the transmission was intended for. In this way, even on a network segment, acting as a single collision domain, each node on that network knows when traffic is intended for it.
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