QSFP112 Fibre Optic Transceiver Technology Overview

QSFP112 400G

QSFP112 (Quad Small Form-factor Pluggable 112) is a 4-channel fibre optic transceiver supporting data rates up to 400Gbps by targeting 112Gbps per channel. These modules are backward compatible with legacy QSFP+, QSFP28 and QSFP56 technology as well as conforming to QSFP-DD standards. This allows data centres to effectively scale and future proof their networks while still utilising existing hardware.

There are two common types of QSFP112 transceiver:

Single-mode – designed for longer transmission distances utilising single-mode fibre optic cables to support applications over several kilometres.
Multi-mode – designed for short range applications within data centres using multi-mode fibre optic cables.

Standards & Protocols

IEEE Std 802.3db
QSFP112 MSA
CMIS 4.0
IEEE Std 802.3ck
CMIS 5.0
IEEE 802.3cu
OIF-CEI-112G-VSR-PAM4
CMIS Rev 4.0
IEEE 802.3bs
OIF-CEI-112G-VSR-PAM4
CMIS Rev 5.2

Optical Standards

Format	Reach	Media Type	Connector	Wavelength
QSFP112-400G-VR4	30m/50m (OM3/OM4)	MMF	MTP/MPO-12	850nm
QSFP112-400G-SR4	50m	MMF	MTP/MPO-12	850nm
QSFP112-400G-FR4	2km	SMF	LC Duplex	1310nm
QSFP112-400G-DR4	500m	SMF	MTP/MPO-12	1310nm
QSFP112-400G-LR4	10km	SMF	LC Duplex	1310nm
QSFP112-400G-XDR4	2km	SMF	MTP/MPO-12	1310nm

QSFP112 vs QSFP-DD

Both QSFP112 and QSFP-DD form-factors support 400G speeds and maintain backward compatibility with legacy QSFP technology. However, they differ in their internal configuration and design. QSFP-DD stands for “Quad Small Form-factor Pluggable – Double Density”, meaning it has eight internal channels as opposed to four.

For 400G data rates, these target 50Gbps each whereas the four channels in QSFP112 modules target 112Gbps. The QSFP-DD form factor is also used in 200G and 800G applications, making it a more versatile option. However, its increased channel density requires more power to operate, resulting in a higher cost per bit compared to QSFP112.

See our Tech Talk blog for more information on 400G technology.