The first experimental version of Ethernet wired networking ran at a connection speed of 2.94 megabits per second (Mbps) in 1973. By the time Ethernet became an industry-standard in 1982, its speed rating increased to 10 Mbps due to improvements in the technology. Ethernet kept this same speed rating for more than 10 years. Different forms of the standard were named starting with the number 10, including 10-Base2 and 10-BaseT.
The technology called Fast Ethernet was introduced in the mid-1990s. It picked up that name because Fast Ethernet standards support a maximum data rate of 100 Mbps, 10 times faster than traditional Ethernet. Other common names for this standard included 100-BaseT2 and 100-BaseTX.
Fast Ethernet was widely deployed as the need for greater LAN performance became critical to universities and businesses. A key element of its success was its ability to coexist with existing network installations. Mainstream network adapters of the day were built to support both traditional and Fast Ethernet. These 10/100 adapters sense the line speed automatically and adjust connection data rates accordingly.
Gigabit Ethernet Speeds
Just as Fast Ethernet improved on traditional Ethernet, Gigabit Ethernet improved on Fast Ethernet, offering rates up to 1000 Mbps. Although 1000-BaseX and 1000-BaseT versions were created in the late 1990s, it took years for Gigabit Ethernet to reach large-scale adoption due to its higher cost.
10 Gigabit Ethernet operates at 10,000 Mbps. Standard versions including 10G-BaseT were produced starting in the mid-2000s. Wired connections at this speed were only cost-effective in certain specialized environments such as in high-performance computing and data centers.
40 Gigabit Ethernet and 100 Gigabit Ethernet technologies have been under active development for some years. Their initial usage is primarily for large data centers. 100 Gigabit Ethernet is already replacing 10 Gigabit Ethernet in the workplace and in the home.
Ethernet's Maximum Speed Versus Actual Speed
The speed ratings of Ethernet have been criticized for being unachievable in real-world usage. Similar to the fuel efficiency ratings of automobiles, network connection speed ratings are calculated under ideal conditions that may not represent normal operating environments. It is not possible to exceed these speed ratings as they are maximum values.
There's no specific percentage or formula that can be applied to the maximum speed rating to calculate how an Ethernet connection will perform in practice. Actual performance depends on many factors, including line interference or collisions that require applications to retransmit messages.
Because network protocols consume some amount of network capacity to support the protocol headers, applications cannot get 100% just for themselves. It is also more difficult for applications to fill a 1000 Gbps connection with data than to fill a 100 Mbps connection. However, with the right applications and communication patterns, actual data rates can reach over 90% of the theoretical maximum during peak usage.