Describe data link control.
The Open Systems Interconnection (OSI) model has seven layers that perform different functions. One of the OSI model layers is the data link layer responsible for network communication and data transfer. The layer is responsible for establishing and providing a reliable and efficient data transfer platform across different networks. Therefore, Data Link Control (DLC) is the service provided by the data link layer of the OSI model. For example, some networks only allow the transfer of one piece of data at a time. Suppose several pieces of data are transmitted simultaneously. In that case, they are likely to collide, which may lead to data loss or any other unanticipated network failure. Therefore, data link control provides the requisite coordination between networks so that there is minimal network traffic or congestion that would otherwise translate into data loss.
Identify two functions that are performed by the DLC.
DLC performs three primary functions; line discipline, error, and flow control. To start with, line discipline determines the devices responsible for data transfer and when the data will be transferred. Line discipline is normally achieved through END/ACK and poll/select. Inquiry/Acknowledgement is whereby the transmitter device sends an inquiry to the receiver asking whether they are ready and available to receive the data. On the other end, the receiver replies with an acknowledgment, which can either be positive or negative. The second function of DLC is flow control. This is whereby the sender communicates to the receiver of their intention to send a particular data size. In case the receiver has limited space, the system sends a communication notifying the sender to suspend the transfer of data temporarily. This can be achieved through two main methods; the stop and wait method and the slide window method. Finally, in the process of data transfer, some errors may occur. Therefore, the third function of DLC is error control. This is a technique used to detect errors and retransmit the data if it is permanently damaged or lost.
Why do you think those functions that you have identified are essential to successful data transmission?
The functions mentioned above are very crucial in the process of data transfer. This is because if the receiver and the sender cannot communicate, data may be lost in the process or permanently damaged, which may translate into huge losses for the organization. Therefore, both the sender and the receiver must establish a clear communication so that even before data is transmitted, the receiver has already confirmed their storage space’s adequacy to mitigate data loss due to the unavailability of storage space.