400GBASE-LR4-6 Application Overview


400GBASE-ER8, 400GBASE-FR4, 400GBASE-FR8, 400GBASE-LR4-6, 400GBASE-LR8
400GBASE-LR4-6: 400 Gb/s wavelength-division multiplexed (WDM) PAM4 serial transmission over 2 single‑mode optical fibers, with reach up to at least 6 km

400GBASE-LR4-6 supports four long wavelength WDM 4‑level pulse amplitude modulated (PAM4) serial transmission over duplex (2‑fiber) single‑mode optical fiber cabling. The application’s equivalent symbol rate is 425 GBd per lane (PAM4 maps pairs of bits into a single symbol) lane and the supported distance varies according to the type of single‑mode cable used. Network equipment interface connections include a duplex optical fiber connector and a standard socket into which physical (PHY) layer transceiver modules may be plugged.

  • Connector type: LC
  • Transceiver module: QSFP-DD
  • Defined in clause 151 of the IEEE 802.3 Standard for Ethernet
  • Initially published as IEEE Std 802.3cu™: Physical Layers and Management Parameters for 100 Gb/s and 400 Gb/s Operation over Single‑Mode Fiber at 100 Gb/s per Wavelength in 2021

Optical Fiber Cabling (Channel) Characteristics:

Parameter OS1a Indoor/Outdoor OS2
Operating wavelengths: 1271 nm, 1291 nm, 1311 nm, and 1331 nm
Specification wavelength: 1310 nm
Insertion loss (max): 6.3 dB
Cabled fiber attenuation (max): 1.0 dB/km 0.5 dB/km 0.4 dB/km
Operating range2: 2 m to 4 km1 2 m to 6 km 2 m to 6 km
1 Operating range for cabled fibers having more than 0.5 dB/km attenuation is not specified by IEEE 802.3. This calculation is provided for information only.
2 Maximum operating ranges are calculated using a 2.0 dB connection and splice loss allocation.

Key Application Capabilities:

  • Defines a 400 Gb/s PHY using four WDM lanes for operation over at least 6 km of SMF
  • Supports full-duplex operation only
  • Preserves the Ethernet frame format utilizing the Ethernet MAC
  • Preserves minimum and maximum FrameSize of current 802.3 Standard for Ethernet
  • Provides appropriate support for optical transport networks (OTNs)
  • Supports a BER of better than or equal to 10-13 at the MAC/PLS service interface (or the frame loss ratio equivalent)
  • Supports optional Energy-Efficient Ethernet operation

Related Applications:

The IEEE P802.3cu Task Force also specified the following 100 Gb/s per wavelength Ethernet applications:

Application    Operating    Wavelength Media Operating Range1
100GBASE-FR1 1310 nm Single-mode up to 2 km
100GBASE-LR1 1310 nm Single-mode up to 10 km
400GBASE-FR4 1310 nm Single-mode up to 2 km
1 Supported distance varies according to the type of optical fiber cable used.

Back to TIA FOTC IEEE 802.3 Single-mode Optical Fiber Ethernet Standards Explorer