Two Standards for Ethernet

Two Standards for Ethernet

Ethernet was originally created in the 1970s by Robert Metcalfe and some others working for Xerox corporation in Palo Alto, California. They got Intel involved, convincing them to put Ethernet logic on a computer chip, making the mass production of Ethernet cards less expensive. They also got Digital Equipment Corporation (Digital), the second-largest computer maker at the time, to support Ethernet. So, the original standard, as defined by those companies, came to be called DIX Ethernet, using the first letters of those three companies in the name. That standard is also known as Ethernet Version 2; the final version created by these three companies was the second version of their Ethernet protocol specifications.

Because the IEEE was standardizing several LAN standards at the same time, it noticed that several functions on each type of LAN were similar. So, to create the standards, the IEEE created a committee to define the Ethernet standards and protocols that were unique to Ethernet. It created another committee to establish standards and protocols that are shared between Ethernet and several other types of LANs. The IEEE named the committee for Ethernet-specific standards the 802.3 committee, and it called the committee that defined common LAN features the 802.2 committee. The 802.3 standard is also called Media Access Control (MAC), and the 802.2 standard is also called Logical Link Control (LLC).

In this chapter, you read about several fields that were either in the Ethernet header or trailer. Figure 5-8 shows the header defined by 802.3 and 802.2, as well as the trailer, as defined by 802.3.