25GBASE-LR Application Overview


25GBASE‑LR: 25 Gb/s serial transmission at 1310 nm over 2 single‑mode optical fibers, with reach up to at least 10 km

25GBASE-LR supports long wavelength serial transmission over duplex (2‑fiber) single‑mode optical fiber cabling. The application’s nominal symbol rate is 25.78125 GBd per 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: SFP28
  • Defined in clause 114 of the IEEE 802.3 Standard for Ethernet
  • Initially published as IEEE Std 802.3cc™: Physical Layer and Management Parameters for Serial 25 Gb/s Ethernet Operation Over Single-Mode Fiber in 2017

Optical Fiber Cabling (Channel) Characteristics:

Parameter OS1a Indoor/Outdoor OS2
Operating 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 8 km1 2 m to 10 km
1 Operating range for cabled fibers having other than 0.4 dB/km attenuation is not specified by IEEE 802.3. These calculations are 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 25 Gb/s PHY for operation over at least 10 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 10-12 at the MAC/PLS service interface (or the frame loss ratio equivalent)
  • Supports optional Energy-Efficient Ethernet operation

Related Applications:

The IEEE P802.3cc Task Force also specified the following 25 Gb/s Ethernet application:

Application    Operating    Wavelength Media Operating Range1
25GBASE-ER 1310 nm Single-mode up to 40 km2
1 Supported distance varies according to the type of optical fiber cable used.
2 Links longer than 30 km for the same link power budget are considered engineered links and must not exceed specified insertion loss.

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