IEEE 802.3 is a working group and a collection of Institute of Electrical and Electronics Engineers (IEEE) standards produced by the working group defining the physical layer and data link layer’s media access control (MAC) of wired Ethernet. This is generally a standard for Ethernet, which is the most widely used local area network (LAN) technology.

Here are the key points regarding IEEE 802.3 – Ethernet:

  1. Origins: IEEE 802.3 is a standardization derived from the original Ethernet specification as introduced by Xerox, DEC, and Intel in the early 1980s.
  2. Media: Over the years, the IEEE 802.3 standard has been adapted to support various types of media including coaxial cables, twisted pair cables, and fiber optics.
  3. Speeds: The standard has been revised to accommodate different speeds, from the original 10 Mbps (10BASE-T) to 100 Mbps (Fast Ethernet, 100BASE-T) to 1 Gbps (Gigabit Ethernet, 1000BASE-T) and even up to 100 Gbps and beyond.
  4. Frame Format: The Ethernet frame starts with a preamble and start frame delimiter, followed by MAC destination and source addresses, type field, data and pad, and finishes with a frame check sequence (FCS).
  5. CSMA/CD: The original Ethernet used Carrier Sense Multiple Access with Collision Detection (CSMA/CD) as the method to manage access to the network medium. As the speeds increased and networks evolved, the role of CSMA/CD diminished, especially with the advent of Ethernet switches and full-duplex operation.
  6. Variants: IEEE 802.3 has numerous variants to accommodate different physical media (like 802.3u for Fast Ethernet, 802.3ab for Gigabit Ethernet over twisted pair, and 802.3z for Gigabit Ethernet over fiber).
  7. Power over Ethernet (PoE): IEEE 802.3af and 802.3at are standards for delivering power over Ethernet cables. This allows devices like IP phones and security cameras to receive power and data over the same cable.
  8. Duplex: Originally, Ethernet operated in half-duplex mode, meaning data could either be transmitted or received at any given time, but not both. With the introduction of switches and the decline of hubs, full-duplex operation became more common, allowing simultaneous transmission and reception of data.

In essence, IEEE 802.3 is a foundational standard for wired Ethernet technology, which has been and continues to be a dominant LAN technology worldwide. Over the years, its revisions and extensions have ensured that Ethernet remains relevant, efficient, and adaptable to the changing demands of networking.