Selecting the Right QSFP28 Module

With so many different QSFP28 optical transceiver modules available for 100G connections, it can sometimes be overwhelming to decide on which module is the right one. This article provides a step-by-step guide to selecting the right type of QSFP28 module.

1. Define the Application

• What are you connecting?

  • Server to Switch?

  • Switch to Switch?

  • Data Center Interconnect (DCI)?

  • Metro connection (citywide)?

• Different applications need different distances, speeds, and cabling.

2. Measure the Distance

Distance	Suggested QSFP28
≤ 5 meters	DAC (Direct Attach Copper)
5–100 meters	AOC (Active Optical Cable) or SR4
100m – 500m	PSM4
500m – 2km	CWDM4
2–10km	LR4
10–40km	ER4
40–80km	ZR4

3. Check Existing Cabling

• Multimode fiber (OM3/OM4)? ➔ Choose SR4.

• Single-mode fiber (SMF)? ➔ Choose LR4, CWDM4, ER4, ZR4.

• No fiber? ➔ If short, use DAC; if longer, use AOC.

4. Identify Connector Type

• MPO/MTP Connector:

  • Needed for SR4 and PSM4 (multi-fiber ribbon cables).

• LC Duplex Connector:

  • Needed for LR4, ER4, ZR4, CWDM4 (single-mode fiber pairs).

5. Check Budget and Cost Sensitivity

• Need cheapest option? ➔ DAC or AOC.

• Cost-tolerant but reliable? ➔ CWDM4 is cheaper than LR4.

• Premium long-range? ➔ LR4, ER4, ZR4 (cost increases with range).

6. Check if Breakout (split) is Needed

• 100G → 4x 25G Breakout?

  • Use QSFP28 to 4x SFP28 Breakout Cable.

• Standard 100G point-to-point?

  • Use standard QSFP28 module (SR4, LR4, etc.)

GigOptics - Your Trusted Source for Optics

At GigOptics, we offer a wide range of optical transceivers including 100G QSFP28 modules; all tested to ensure quality and reliability. For more information, contact us at info@gigoptics.com.