- Catherine
John Doe
Answered on 7:51 am
The difference between 400G-BIDI, 400G-SRBD and 400G-SR4.2 is mainly in the naming convention and the form factor of the modules. They are all based on the same principle of using four pairs of multimode fibers, each carrying two wavelengths of 25G signals in both directions, for a total of 400G bandwidth. The term 400G-BIDI is a generic name for this technology, while 400G-SRBD and 400G-SR4.2 are specific names for the modules that implement it.
The 400G-SRBD module is based on the QSFP-DD form factor, which is a double-density version of the QSFP form factor. It has an MPO-12 connector that can be plugged into an existing QSFP port. The 400G-SRBD module can also be used for breakout applications, where it can be connected to four 100G-BIDI modules that use the QSFP28 form factor.
The 400G-SR4.2 module is based on the OSFP form factor, which is a new form factor designed for higher power and thermal performance. It has an MPO-16 connector that can support higher fiber counts and longer distances. The 400G-SR4.2 module can also be used for breakout applications, where it can be connected to four 100G-SR1.2 modules that use the SFP-DD form factor.
Both the 400G-SRBD and the 400G-SR4.2 modules are compliant with the IEEE 802.3bm protocol and the 400G BiDi MSA specification. They can support link lengths of up to 100m over OM4 multimode fiber.
People Also Ask
QSFP112 Module Types: VR4, SR4, DR4, FR4 and LR4 Compared
Send a request for “a 400G QSFP112 module” to three different vendors and you may receive three different recommendations. One vendor may quote a DR4. Another may suggest a DR4+. A third may ask about your installed fiber infrastructure and explain that neither option matches your deployment requirements. That is not
QSFP112 vs OSFP: Choosing the Right 400G Form Factor
At first glance, QSFP112 and OSFP look like two competing form factors for high-speed networking. Both appear in 400G systems, both support PAM4 signaling, and both are widely used in AI and HPC infrastructure. But treating this as a simple “QSFP112 or OSFP?” decision misses the bigger picture. The right
QSFP112 Transceiver: Complete 400G Guide (2026)
Ask five network engineers whether they should deploy QSFP112 or QSFP-DD for a 400G network, and you may get five different answers. Both form factors can support 400G, both are widely available, and both have legitimate advantages depending on the platform. The right choice depends on your switch or NIC
QSFP112 NVIDIA AI Clusters: ConnectX-7 and BlueField-3
You cannot directly install a QSFP112 transceiver into an NVIDIA Quantum-2 or Spectrum-4 switch port. These switch platforms use OSFP-based cages, while QSFP112 is designed primarily for NVIDIA adapter-side and DPU-side connectivity. This difference often causes confusion when engineers deploy NVIDIA 400G AI networks. A common assumption is that the
FiberMall Analyzes the UPO NPO Framework for 224G and 6.4T Optical Interconnect
The 2026 Open Data Center Conference (ODCC) and the inaugural Compute Expo provided a clearer view of how optical interconnect architectures may evolve inside AI data centers as electrical interconnect scaling becomes increasingly challenging. The event highlighted UPO (Ultra Performance Optics), an NPO (Near-Package Optics) framework developed through ODCC ecosystem
Related Articles
800G SR8 and 400G SR4 Optical Transceiver Modules Compatibility and Interconnection Test Report
Version Change Log Writer V0 Sample Test Cassie Test Purpose Test Objects：800G OSFP SR8/400G OSFP SR4/400G Q112 SR4. By conducting corresponding tests, the test parameters meet the relevant industry standards, and the test modules can be normally used for Nvidia (Mellanox) MQM9790 switch, Nvidia (Mellanox) ConnectX-7 network card and Nvidia (Mellanox) BlueField-3, laying a foundation for
QSFP112 Compatibility Guide: Switches, NICs and CMIS
Priya spent most of a Tuesday morning troubleshooting a link that should have taken four minutes to bring up. She inserted a 400G QSFP112 module into an older leaf switch with a compatible-looking QSFP cage, watched the switch inventory recognize the module, and waited for the port status to turn
QSFP112 Module Types: VR4, SR4, DR4, FR4 and LR4 Compared
Send a request for “a 400G QSFP112 module” to three different vendors and you may receive three different recommendations. One vendor may quote a DR4. Another may suggest a DR4+. A third may ask about your installed fiber infrastructure and explain that neither option matches your deployment requirements. That is not
QSFP112 vs OSFP: Choosing the Right 400G Form Factor
At first glance, QSFP112 and OSFP look like two competing form factors for high-speed networking. Both appear in 400G systems, both support PAM4 signaling, and both are widely used in AI and HPC infrastructure. But treating this as a simple “QSFP112 or OSFP?” decision misses the bigger picture. The right
QSFP112 Transceiver: Complete 400G Guide (2026)
Ask five network engineers whether they should deploy QSFP112 or QSFP-DD for a 400G network, and you may get five different answers. Both form factors can support 400G, both are widely available, and both have legitimate advantages depending on the platform. The right choice depends on your switch or NIC
QSFP112 NVIDIA AI Clusters: ConnectX-7 and BlueField-3
You cannot directly install a QSFP112 transceiver into an NVIDIA Quantum-2 or Spectrum-4 switch port. These switch platforms use OSFP-based cages, while QSFP112 is designed primarily for NVIDIA adapter-side and DPU-side connectivity. This difference often causes confusion when engineers deploy NVIDIA 400G AI networks. A common assumption is that the
FiberMall Analyzes the UPO NPO Framework for 224G and 6.4T Optical Interconnect
The 2026 Open Data Center Conference (ODCC) and the inaugural Compute Expo provided a clearer view of how optical interconnect architectures may evolve inside AI data centers as electrical interconnect scaling becomes increasingly challenging. The event highlighted UPO (Ultra Performance Optics), an NPO (Near-Package Optics) framework developed through ODCC ecosystem