QSFP28 100G BiDi Simplex LC Optics

By Tim (CCIE #41594) November 2nd, 2025 16 views

Overview - QSFP28 100G BiDi (10 km - 80 km)

QSFP28 100G BiDi Optics brings high-density 100G connectivity to single-mode fiber links while significantly reducing fiber count and cabling complexity. Utilizing a QSFP28 package and wavelength division multiplexing (WDM) technology, QSFP28 100G BiDi Optics allows transmit and receive signals to share the same physical fiber pair. With a transmission distance range of 10 km to 80 km, it covers short-distance metropolitan area network links and long-distance enterprise/edge links, providing flexibility for various deployment scenarios.

Parameter Comparison:

In QSFP28 100G BiDi Optics, ranges of 10km, 20km, 40km, and 80km are typically available. Their technical characteristics differ, as compared below:

INPHE Optics Model	Optical Channel	Modulation(Optical)	Rate (Optical)	Interface	Wavelength	FEC
100G BiDi 10km	LR1	1x 106.25G PAM4	106.25Gb/s	Simplex LC	1271nm & 1331nm	KP1 (544,514)
100G BiDi 20km	eLR1	1x 106.25G PAM4	106.25Gb/s	Simplex LC	1291nm & 1311nm	KP1 (544,514)
100G BiDi 40km	ER1	1x 106.25G PAM4	106.25Gb/s	Simplex LC	1304.58nm & 1309.14nm	KP1 (544,514)
100G BiDi 80km	ZR4	4x 25.78G NRZ	103.10Gb/s	Simplex LC	1270nm(4λ) & 1310nm(4λ)	KR4 (528,514)

Areas requiring attention: FEC

As shown in the diagram above, at the optical layer, 10km/20km/40km transmissions use single-wavelength technology. However, due to current technological limitations, 100G single-wavelength transmission cannot reach 80km, so 80km transmission uses 4-wavelength technology.

The 100G BiDi 10km/20km/40km transceiver uses 100G single-wavelength technology and has built-in FEC, so FEC does not need to be enabled on the network device.

The 100G BiDi 80km transceiver uses 100G 4-wavelength technology. The transceiver does not have built-in FEC, so FEC must be enabled on the network device, and this is mandatory. It uses Reed-Solomon KR4 (528,514).

How to use:

100G BiDi is a relatively new technology, and many brands of network equipment do not currently support this Optics type. Therefore, we usually encode it as 100G LR4, ER4, LR1, ER1, etc., to enable its operation.

INPHE's 100G BiDi is compatible with all major brands of switches and routers, such as Cisco, Juniper, Arista, Dell, Nokia, and Huawei, offering plug-and-play functionality.

Compatible part numbers:

In addition to the following official part numbers, even if the OEM brand does not offer models such as 100G BiDi 40km/80km, we can still enable INPHE's 100G BiDi 40km/80km to run on its network equipment.

INPHE Optics Model	Cisco Part Number	Juniper Part Number
100G BiDi 10km	/	740-173673 (QSFP-100G-LRBD-U)
100G BiDi 10km	/	740-173674 (QSFP-100G-LRBD-D)
100G BiDi 20km	QSFP-100G-B20U4-I	/
100G BiDi 20km	QSFP-100G-B20D4-I	/
100G BiDi 40km	/	740-173676 (QSFP-100G-ERBD-U)
100G BiDi 40km	/	740-173677 (QSFP-100G-ERBD-D)
100G BiDi 80km	/	/

Thanks for reading.

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