Fast Ethernet, also known as IEEE 802.3u, is a standard for Ethernet networks that operates at a data rate of 100 megabits per second (Mbps). It is an evolution of the original Ethernet (IEEE 802.3) standard, which operated at a data rate of 10 Mbps. Fast Ethernet was introduced to provide higher data transmission speeds and improve network performance. Here are some key features of Fast Ethernet:

  1. Data Rate: Fast Ethernet operates at a data rate of 100 Mbps, which is ten times faster than the original Ethernet standard. This increased speed allowed for faster data transmission and improved network responsiveness.
  2. Backward Compatibility: Fast Ethernet is designed to be backward compatible with traditional Ethernet (10 Mbps) networks. This means that Fast Ethernet devices can communicate with Ethernet devices using compatible hardware and protocols.
  3. Physical Media: Fast Ethernet supports the same physical media as traditional Ethernet, including twisted-pair cables (e.g., Cat5) and fiber-optic cables. However, to achieve the higher data rate, improved cable quality and specifications are required.
  4. Autonegotiation: Fast Ethernet introduced the autonegotiation feature, which allows devices to automatically determine the best operating mode and data rate when connecting to a network. This ensures compatibility between devices with varying capabilities.
  5. Switching and Hubs: Fast Ethernet networks commonly use switches to improve performance by intelligently forwarding data to the appropriate devices. This reduces network collisions and enhances overall network efficiency. Hubs are still used but are less efficient in terms of network performance.
  6. Full Duplex: Fast Ethernet introduced full-duplex operation, which allows devices to transmit and receive data simultaneously. This further improves network performance and reduces the likelihood of collisions.
  7. Media Dependent Interface (MDI) and Media Dependent Interface-Crossover (MDI-X): Fast Ethernet introduced these two types of interfaces to support different cable types. MDI is used to connect to network devices (e.g., computers), while MDI-X is used to connect similar devices (e.g., switches).
  8. Evolution: Fast Ethernet served as an important stepping stone in the evolution of Ethernet technology. It laid the foundation for even faster Ethernet standards, such as Gigabit Ethernet (IEEE 802.3ab), which operates at 1 Gbps.

Fast Ethernet played a significant role in improving network performance and accommodating the increasing demands of data transmission in local area networks. While newer standards have since surpassed its data rate, Fast Ethernet’s impact on networking technology is still evident today.