Understanding the Fundamentals of Ethernet

Ethernet operates at layer two of the OSI reference model. Layer two, also known as the Data Link Layer, is subdivided into the Logical Link Control (LLC) layer and the Media Access Control (MAC) layer. Ethernet nodes use a globally-unique 48-bit address called the MAC address to communicate within a network. Datagrams at layer two are called frames. The frame structure used by modern Ethernet is the same as that used by earlier coaxial-cabled Ethernet networks, thus providing a level of backwards compatibility.


The original Ethernet operated at a speed of three megabits per second. Today, typical transmission rates for Ethernet are 10 Mbps, 100 Mbps, and 1000 Mbps (Gigabit Ethernet). 10,000 Mbps (10 Gigabit Ethernet) is now starting to emerge. Faster data rates are always under development.

Ethernet Cable Standards

10-Base-2, also known as thinnet, uses coaxial cable, is limited to 10 Mbps, and a maximum segment length of 185 meters. 10-Base 2 is falling into disuse due to the lower cost and greater simplicity associated with UTP (unshielded twisted pair) cabling.

10-Base-5, also known as thicknet, uses coaxial cable, is limited to 10 Mbps, and a maximum segment length of 500 meters. 10-Base-5 is rarely seen anymore.

10-Base-T uses unshielded twisted pair (UTP) cabl