400GBASE-VR4 Application Overview

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400GBASE-SR4, 400GBASE-VR4, and 400GBASE-SR4.2

400GBASE-VR2: 400 Gb/s PAM4 parallel transmission at 850 nm over 8 multimode optical fibers, with reach up to at least 50 m

400GBASE-VR4 supports short wavelength 4‑level pulse amplitude modulated (PAM4) serial transmission over four lanes (8‑fibers) of multimode optical fiber cabling. The application’s equivalent symbol rate is 106.25 GBd per lane (PAM4 maps pairs of bits into a single symbol) and the supported distance varies according to the type of multimode cable used. Network equipment interface connections include a multi‑fiber push on (MPO) connector and a standard socket into which a physical (PHY) layer transceiver module may be plugged.

  • Connector type: MPO/MTP
  • Transceiver module: QSFP-DD
  • Published as IEEE Std 802.3db™: Physical Layer Specifications and Management Parameters for 100 Gb/s, 200 Gb/s, and 400 Gb/s Operation over Optical Fiber Using 100 Gb/s Signaling in 2022

Optical Fiber Cabling (Channel) Characteristics:

400GBASE-VR4
Parameter OM3 OM4 OM5 Unit
Operating wavelength: 850 nm
Modal bandwidth (min): 2,000 4,700 MHz∙km
Operating range: 0.5 to 30 0.5 to 50 m
Insertion loss (max): 1.6 1.7 dB
Cabling skew (max): 79 ns
Cabling skew variation: 2.4 ns

Key Application Capabilities:

  • Defines a four-lane 400 Gb/s PHY for operation over at least 50 m of MMF
  • 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)

Related Applications:

The IEEE P802.3db Task Force also specified the following PAM4, 106.25 GBd symbol rate Ethernet applications:

Application    Operating    Wavelength Media Operating Range1
100GBASE-SR1 850 nm Multimode up to 100 m
100GBASE-VR1 850 nm Multimode up to 50 m
200GBASE-SR2 850 nm Multimode up to 100 m
200GBASE-VR2 850 nm Multimode up to 50 m
400GBASE-SR4 850 nm Multimode up to 100 m
1 Supported distance varies according to the type of optical fiber cable used.

Back to TIA FOTC IEEE 802.3 Multimode Optical Fiber Ethernet Standards Explorer