To better understand the functionality of and the services provided by the link layer, we
can divide the data-link layer into two sublayers: data link control (DLC) and media
access control (MAC). This is not unusual because, as we will see in later chapters, LAN
protocols actually use the same strategy. The data link control sublayer deals with all
issues common to both point-to-point and broadcast links; the media access control sub-
layer deals only with issues specific to broadcast links. In other words, we separate these
two types of links at the data-link layer, as shown in Figure 9.4.