IEEE Std 802.3bw ”IEEE Standard for Ethernet Amendment 1: Physical Layer Specifications and Management Parameters for 100 Mb/s Operation over a Single Balanced Twisted Pair Cable  (100BASE-T1)” was developed by the IEEE P802.3bw 100BASE‑T1 Task Force and approved by the IEEE-SA Standards Board on October 26, 2015. This amendment defines the Physical Layer (PHY) specifications and management parameters for point-to-point full duplex 100 Mb/s Ethernet operation over single balanced twisted-pair cabling on a lower-performance channel. This application is targeted for deployment in automotive, industrial, and other environments that will benefit by a reduction in the number of wire pairs and magnetics.

The link segment for a 100BASE-T1 PHY system consists of up to 15 m of ruggedized single balanced twisted-pair cabling, with up to four in-line connectors and two mating connectors. The mechanical interface to the balanced cabling is a 2-pin connector or two pins of a multi-pin connector, which is not specified by the amendment. All cabling and mechanical interfaces are required to perform in environmentally stressful conditions as defined by referenced ISO General Load, Electrical Load, Mechanical Load, Climatic Load, and Chemical Load specifications.

Goals and Objectives for 100BASE‑T1 operation:

  • Support 100 Mb/s operation in automotive environments (e.g. EMC, temperature) over a single balanced twisted-pair
  • Provide electrical interoperability with existing single balanced twisted-pair 100 Mb/s client interface (OABR* PHY)
  • Preserve the IEEE 802.3/Ethernet frame format at the MAC client service interface
  • Preserve minimum and maximum frame size of the current IEEE 802.3 standard
  • Support full duplex operation only
  • Support a speed of 100 Mbit/s at the MAC/PLS service interface
  • Maintain a bit error ratio (BER) of less than or equal to 10-10 at the MAC/PLS service interface
  • Do not preclude the ability to survive automotive fault conditions (e.g. shorts, over voltage, EMC, ISO 16750)
  • Support fast-startup operation using predetermined configurations which enables the time from power_on**=FALSE to a state capable of transmitting and receiving valid data to be less than 100ms
  • Support optional operation with run-time configuration, that specifies a maximum allowable time from power_on**=FALSE to a state capable of transmitting and receiving valid data
  • The resulting standard will not preclude single pair auto-negotiation
  • Define the performance characteristics of a link segment and a PHY to support point-to-point operation over this link segment with single twisted‑pair supporting up to four inline connectors using balanced cabling for at least 15 m reach

The IEEE 802.3 100BASE-T1 Call-For-Interest Consensus Presentation can be found here:

The Project Authorization Request (PAR), approved on August 21, 2014, can be found here:

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