Ethernet Data Link Protocols
One of the most significant strengths of the Ethernet family of protocols is that these protocols use the same data link standard. In fact, the core parts of the data link standard date back to the original Ethernet standards.
The Ethernet data link protocol defines the Ethernet frame: an Ethernet header at the front, the encapsulated data in the middle, and an Ethernet trailer at the end. Ethernet actually defines a few alternate formats for the header, with the frame format shown in Figure 2-14 being commonly used today.
While all the fields in the frame matter, ...