50GBASE-SR Application Overview

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50GBASE-SR

50GBASE‑SR: 50 Gb/s PAM4 serial transmission at 850 nm over 2 multimode optical fibers, with reach up to at least 100 m

50GBASE‑SR supports short wavelength 4‑level pulse amplitude modulated (PAM4) serial transmission over duplex (2‑fiber) multimode optical fiber cabling. The application’s equivalent symbol rate is 53.125 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 duplex optical fiber connector and a standard socket into which a physical (PHY) layer transceiver module may be plugged.

  • Connector type: LC
  • Transceiver module: QSFP+
  • Defined in clause 138 of the IEEE 802.3 Standard for Ethernet
  • Initially published as IEEE Std 802.3cd™: Media Access Control Parameters for 50 Gb/s and Physical Layers and Management Parameters for 50 Gb/s, 100 Gb/s, and 200 Gb/s Operation in 2018

Optical Fiber Cabling (Channel) Characteristics:

50GBASE-SR
Parameter OM3 OM4 OM5 Unit
Operating wavelength: 850 nm
Modal bandwidth (min): 2,000 4,700 MHz∙km
Operating range: 0.5 to 70 0.5 to 100 m
Insertion loss (max): 1.8 1.9 dB

Key Application Capabilities:

  • Defines a 50 Gb/s PHY for operation over at least 100 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 10-12 at the MAC/PLS service interface (or the frame loss ratio equivalent) for 50 Gb/s operation
  • Supports optional Energy-Efficient Ethernet operation

Related Applications:

The IEEE P802.3cd Task Force also specified the following PAM4 modulated Ethernet applications:

Application    Operating    Wavelength Media Operating Range1​
50GBASE-CR – Copper Twinax up to 3 m
50GBASE-FR 1310 nm Single-mode up to 2 km
50GBASE-KR – Backplane –
50GBASE-LR 1310 nm Single-mode up to 10 km
100GBASE-CR2 – Copper Twinax up to 3 m
100GBASE-DR 1310 nm Single-mode up to 500 m
100GBASE-KR2 – Backplane –
100GBASE-SR2 850 nm Multimode up to 100 m
200GBASE-CR4 – Copper Twinax up to 3 m
200GBASE-KR4 – Backplane –
200GBASE-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