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: http://www.ieee802.org/3/DMLT/public/nov12/CFI_01_1112.pdf
The Project Authorization Request (PAR), approved on November 13, 2013, can be found here: http://www.ieee802.org/3/DMLT/PAR_5C_Objectives/8023-DMLT-SG-1311-Winkel-PAR-2013-11-13r3.4.pdf