The Ethernet physical layer has evolved over its existence starting in 1980 and encompasses multiple physical media interfaces and several orders of magnitude of speed from 1 Mbit/s to 800 Gbit/s.OverviewThe specifications of the family of standards are published. Generally, layers are named by their specifications: • 10, 100, 1000, 10G,. – the nominal, usable speed at the top of the physical layer (no suffix = megabit/s, G = gigabit/s), excluding. Starting with Fast Ethernet, the physical layer specifications are divided into three sublayers in order to simplify design and interoperability: • PCS () - This sublayer pe. Several varieties of Ethernet were specifically designed to run over 4-pair copper already installed in many locations. In a departure from both 10BASE-T and 100BASE-TX, 1000BASE-T and above.