The data link layer

The data link layer

The data link layer in the OSI model’s main purpose ensures that data transmitted over the network is error-free; this helps monitor all frames and bits of data within a network. Additionally, this function ensures that the recipient receives the data sent by a sender without any loss of bits of information. For example, if a sender sends 2 kilobytes of information, the same amount of information is received by the recipient in its original format (Langill, 2014). The layer has two sublayers, which is the logical link control (LLC) that handles error notifications and the media access control (MAC) that defines who the recipient(s) of the data. After the information or data is passed on to this layer, it is subdivided into smaller data units that are referred to as frames. This fragmentation of data is necessary to ensure the integrity of data as its flow through the network. An example is a piece of data that may be subdivided into eight frames. This means that even if a middle man were able to intercept the data, he/she would only get bits of the data as opposed to all of it (Mitchell, 2018). To define the destination of each of the frames, the data link layer adds a header to each. The header contains information on the source and the destination of the frames. An example, frame 1 would have a header 1 and frame 8 header 8. This ensures that when the data is reconstructed back, it is done in the original format it was sent.

Another function of the layer is to control the flow of data from the sender to the recipient. This is because at times the rate at which the sender consumes data may differ from the recipient’s rate. For that, the layer manages the flow (Kołodziejczyk, 2012). For example, if the sender’s device sent the information at upload speed of 300 Mbps and the recipient network is at 50 Mbps, the layer ensures that the recipient’s device is not overrun by the sender’s. Lastly, the layer manages control of access to information whenever there are multiple devices in a network. For example, when two stations transmit their information simultaneously in a network, it is necessary to control access to prevent a collision.