IEEE Announces 3 Amendments to the IEEE 802.3 Standard for Ethernet

April 26, 2019 by Gary Elinoff

Demand for Ethernet is growing, necessitating updates to the IEEE 802.3 standard for Ethernet use.

Demand for Ethernet is growing, necessitating updates to the IEEE 802.3 standard for Ethernet use.

It’s hard to overstate the importance of the IEEE 802.3 standard for electronic engineers. It is a group of standards defining the physical layer and the data link layers of the Ethernet. Any manufacturer that wishes to sell products that transfer information or, increasingly, sends electrical energy over the Ethernet must adhere to these standards.

Putting it even more plainly, if IEEE 802.3 doesn’t exactly define the Ethernet, it does provide a roadmap to structure that must be followed.

This week, IEEE announced two new amendments to the standard in response to evolving industry requirements for emerging Ethernet applications. They will provide the governance needed for designers to implement increased Ethernet speeds, enhanced backplane applications, and improved delivery of PoE (power over Ethernet).



As described by David Law, chair of the IEEE 802.3 Working Group, “These refinements are essential to maintain Ethernet as the core technology driving advancements at data centers and throughout network infrastructures everywhere, as well as utilizing Ethernet to power the wide variety of sensors, actuators, cameras and other devices associated with the Internet of Things.”

Below, we provide simple descriptions of the amendments as provided by the IEEE 802.3 Ethernet Working Group. Choosing the links provided for each amendment will bring up the appropriate IEEE page, with instructions on how to purchase the complete document.

IEEE 802.3: The Base Document

The scope of IEEE 802.3 can be characterized by a few concepts:

  • Selected speeds of operation for Ethernet LAN (local area network) are specified from 1 Mb/s to 400 Gb/s with a common MAC (media access control) specification and MIB (management information base)
  • The CSMA/CD (carrier sense multiple access with collision detection) MAC protocol specifications for half duplex and full duplex operation
  • Speed-specific MIIs (media-independent interfaces) that allow the use of selected physical layer (PHY) devices for operation over coaxial, twisted pair or fiber optic cables, or electrical backplanes
  • System considerations for multisegment, shared-access networks describe the use of repeaters that are defined for operational speeds up to 1 Gb/s


A 1976 diagram that was hand-drawn by Robert M. Metcalfe, who is credited as being a co-inventor of the Ethernet. Image from "Ethernet: distributed packet switching for local computer networks" by Robert M. Metcalfe and David R. Boggs via IEEE


Of particular interest is information on the provision of power over selected twisted-pair PHY types.

The Three New IEEE 802.3 Standard Amendments

Amendment 1: IEEE 802.3cb-2018

IEEE 802.3cb-2018 covers physical layer specifications and management parameters for 2.5 Gb/s and 5 Gb/s operations over electrical backplanes.

Major focus of IEEE 802.3cb-2018:

  • Ethernet MAC parameters
  • Physical layer specifications
  • Management objects for the serial transfer of Ethernet format frames at 2.5 Gb/s and 5 Gb/s over electrical backplanes


Amendment 2: IEEE 802.3bt-2018

IEEE 802.3bt-2018 is concerned with physical layer and management parameters for power over Ethernet over four pairs. With the advent of the IoT and remote devices that are not locally powered, this amendment will be of vital concern to power engineers.

Some major factors covered in IEEE 802.3cb-2018:

  • All four pairs will be utilized in transferring electrical power
  • Enhanced power management information for superior power management capabilities


Amendment 3: IEEE 802.3cd-2018

IEEE 802.3cd-2018 covers media access control parameters for 50 Gb/s and associated physical layers as well as management parameters for 50 Gb/s, 100 Gb/s, and 200 Gb/s operation.

Major focus areas of IEEE 802.3cd-2018:

  • Specifications for MAC parameters
  • Physical layer specifications
  • Management parameters for the transfer of format frames at 50 Gb/s, 100 Gb/s, and 200 Gb/s



How has the IEEE 802.3 standard affected your work? What's your opinion on these new amendments and how they reflect the state of the Ethernet? Share your thoughts in the comments below.