Selection Guide for QSFP28 Fiber Optic Line Terminals for Intelligent Buildings

Selecting the right QSFP28 module requires matching fiber type, reach, connector, breakout needs, and switch compatibility to ensure reliable 100G connectivity in intelligent building networks.

1. Understand QSFP28 Basics

QSFP28 (Quad Small Form-factor Pluggable 28) is a hot-pluggable 100G Ethernet transceiver using four 25G NRZ lanes, capable of a raw throughput of 112 Gbps . It supports breakout into four 25G connections, making it versatile for server-to-switch or switch-to-switch links. QSFP28 modules are compatible with modern 100G switches, but ensure your switch supports QSFP28 signaling, as QSFP+ ports are not fully interchangeable due to signaling differences .

2. Define the Application

Identify the type of connection:

• Server-to-Switch or Top-of-Rack (ToR): Typically short distances within racks.
• Switch-to-Switch or Leaf-Spine Fabric: Medium distances within a building or campus.
• Data Center Interconnect (DCI) or Metro Links: Longer distances between buildings or across campuses .

3. Determine Fiber Type and Reach

• Multimode Fiber (MMF): Use SR4 modules for short distances (up to 70m on OM3, 100m on OM4, 150m on OM5) with MTP/MPO-12 connectors .
• Single-Mode Fiber (SMF): Use LR4, CWDM4, ER4, or ZR4 for longer distances (typically 500m to several kilometers) .
• No fiber installed: Consider Direct Attach Copper (DAC) for short links or Active Optical Cables (AOC) for longer runs .

4. Connector Type

• SR4/PSM4: Multi-fiber ribbon cables (MPO/MTP) for parallel transmission.
• LR4/ER4/CWDM4: Single-mode fiber pairs for longer reach .

5. Breakout Requirements

If you need 100G → 4x25G breakout, select QSFP28 modules compatible with SFP28 breakout cables. Standard point-to-point 100G links do not require breakout .

6. Switch Compatibility and Thermal Considerations

• Verify that the switch ASIC supports 25G lanes for QSFP28.
• Check thermal limits and power budget, especially in dense intelligent building racks .

7. Cost and Future-Proofing

• Cost-sensitive deployments: DAC or AOC for short distances.
• Reliable mid-range: CWDM4 for moderate distances.
• Premium long-range: LR4, ER4, or ZR4 for future-proofing and inter-building links .

8. Summary Recommendation

For intelligent building networks:

• Short intra-rack links: SR4 over OM4 MMF.
• Medium intra-building links: CWDM4 or LR4 over SMF.
• Long inter-building links: ER4 or ZR4 over SMF.
• Always verify switch port compatibility, connector type, and breakout needs before deployment to avoid costly mistakes . By following this structured approach, you can ensure high-speed, reliable, and scalable 100G connectivity tailored to intelligent building applications.