Media Access Control

What is it?

Media access control (MAC) refers to the sublayer of the data link layer (DLL) in the seven-layer OSI network reference model, i.e., a framework that describes networking and telecommunications systems.

In simple terms, media access control determines the way data is transmitted over a network cable. It simplifies the transit of data packets between two computers and prevents issues like collision or concurrent data transfer.

How does it work?

The goal of media access control is to ensure an addressing mechanism and channel access. This is meant for each node in the network to interact with other nodes on the same or other networks.

MAC is designed to transfer data packets to and from a network interface card, a hardware component installed on a computer to connect it to the network. Additionally, it serves to transmit data to and from another remotely shared channel.

The MAC address links to the network interface card. The latter transforms data into electric signals that can be transferred through the web.

Methods of media access control

First, carrier sense multiple access with collision avoidance (CSMA/CA) is a way to regulate how data packets are transferred between two computer nodes. It is intended to evade collision by setting each computer terminal to make a signal before transfer.

On the other hand, carrier sense multiple access with collision detection (CSMA/CD) is about sensing transmission from other stations in the channel and starting to transmit data when the channel is clear. In case of collision, transmission is stopped, and a jam signal is given out.

Another method is the demand priority, which necessitates network terminals obtaining authorization from the so-called active hub before data can be transferred.

Lastly, token passing is a technique that allows for avoiding collision by authoring a single computer to transfer data. This computer is required to possess a free token (a small data frame).