Imported SFP optical module QSFP28

QSFP28 (Quad Small Form-Factor Pluggable 28) modules are high-speed 100G optical transceivers that support four 25G lanes, offering flexible deployment for data centers and enterprise networks.

Overview

QSFP28 modules are compact, hot-swappable optical transceivers designed for 100 Gigabit Ethernet (100GbE). The "28" indicates a maximum signaling rate of 28 Gbps per lane, while the four lanes aggregate to deliver 100 Gbps payload using 25G NRZ encoding . These modules maintain the same mechanical dimensions as QSFP+ (40G) modules, allowing high port density and backward compatibility with QSFP+ ports, though QSFP28 modules cannot operate in legacy QSFP+ ports .

Module Types and Reach

Imported QSFP28 modules come in various optical types depending on distance and fiber type:

• SR4 (Short Reach): Uses 850nm VCSELs over multimode fiber (OM3/OM4) with MPO-12 connectors, supporting up to 70m on OM3 and 100m on OM4 .
• LR4 (Long Reach): Single-mode DFB lasers over duplex single-mode fiber, typically supporting distances up to 10 km.
• DR (Direct Reach): Single-wavelength PAM4 modulation over single-mode fiber, supporting up to 500m with duplex LC connectors .
• ZR (Extended Reach): Coherent optics module capable of 80 km over dark fiber and up to 300 km over amplified DWDM links, suitable for metro and interconnect applications .

Electrical and Optical Interfaces

QSFP28 modules use CAUI-4 electrical interfaces, with four transmit (Tx) and four receive (Rx) differential pairs. Each lane operates at ~25.78125 Gbps with 64b/66b encoding . The optical interface varies by module type:

• Parallel fibers for SR4/PSM4
• Single wavelength for DR/LR4/ZR
• MPO/MTP connectors for multimode parallel optics
• Duplex LC connectors for single-mode optics

Standards and Compatibility

All QSFP28 modules comply with QSFP28 MSA and IEEE 802.3bm standards, ensuring interoperability across vendors. Imported modules are often certified for use with major switch brands like Cisco, Arista, Juniper, and Brocade . Digital Diagnostic Monitoring (DDM) is supported, providing real-time monitoring of temperature, voltage, transmit/receive power, and laser bias current .

Power Consumption

Typical QSFP28 modules consume 3.5 W to 4.5 W, depending on type and reach. Extended reach or coherent modules like ZR may consume up to 6 W .

Deployment Considerations

When selecting imported QSFP28 modules, consider:

• Distance requirements and fiber type
• Switch port compatibility and firmware support
• Power budget and thermal management
• Migration plans from 40G QSFP+ to 100G QSFP28
• Vendor certification to ensure reliable operation and warranty compliance Imported QSFP28 modules provide flexible, high-density 100G connectivity for data centers, enterprise cores, and service provider networks, with options ranging from short-reach multimode to long-reach coherent optics.