Some of the features specifically associated with the MAC is it conforms to IEEE 802.3 standard, which is also called Fast Ethernet. It is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. Of the Fast Ethernet standards, 100BASE-TX is by far the most common and is supported by the vast majority of Ethernet hardware being currently produced. The MAC on TM4C129x devices also conforms to IEEE 1588-2008 standard. This standard describes a hierarchical master-slave architecture for clock distribution. Under this architecture, a time distribution system consists of one or more communication media (network segments), and one or more clocks. In addition to that, several design enhancements have been made that result in better performance at the MAC level and allow for much lighter CPU loading due to ENET traffic, freeing up the core to do other important application specific tasks.