IEEE Std 802.3br™ “Standard for Ethernet Amendment 5: Specification and Management Parameters for Interspersing Express Traffic” was developed by the IEEE P802.3br Interspersing Express Traffic Task Force and approved by the IEEE-SA Standards Board on June 30, 2016. Ethernet use in industrial (e.g. factory, process, and building automation) and automotive networks is growing with more than a dozen purposeful industrial protocols currently serving these networking needs. This amendment addresses prioritization of express and non-express frames in converged traffic environments where control data is time‑sensitive and often requires minimum latency.

Goals and Objectives for Interspersing Express Traffic operation:

  • Preserve the IEEE 802.3 Ethernet frame format at the MAC
  • Preserve minimum and maximum MAC frame size of the current IEEE 802.3 standard
  • Use the Clause 4/Annex 4A MAC without alteration
  • Require no changes to PHYs
  • Support full duplex operation only
  • Preserve MAC/PLS service interface
  • Do not degrade  Mean Time to False Packet Acceptance (MTTFPA) at the MAC Service Interface
  • The latency to initiate the transmission of an express frame shall be less than two times the minimum packet size plus IPG
  • Assure that both ends of the link support Interspersing Express Traffic (IET) mode before enabling it
  • Provide a primitive at the MAC client service interface to inhibit the transmission of non-express frames
  • Provide two MAC client service interfaces at each end of the IET link, as the means to distinguish between the express and the non-express frames
  • Minimum IET frame size shall be greater than or equal to 64 bytes
  • IET frames will be constructed such that they will not be recognized as valid MAC frames by a non-IET-capable device

The IEEE 802.3 Distinguished Minimum Latency Traffic in a Converged Traffic Environment Call‑For‑Interest Consensus Presentation can be found here:

The Project Authorization Request (PAR), approved on November 13, 2013, can be found here:

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