100GBASE-ER4 QSFP28 Module 1310nm 40km LC - Reliable Long-Reach 100G

In this review the QSFPTEK 100GBASE-ER4 QSFP28 module is evaluated for network engineers and data center operators who need a reliable 100G link across single-mode fiber. The bottom line is that this transceiver delivers practical long-reach performance and monitoring features in a compact QSFP form factor, making it a solid choice for rack-to-rack and client-side 100G interconnections where up to 40km reach and low power draw matter. It is not an exotic optics solution, but it is straightforward to deploy and maintain.

Key Features

• 4-channel QSFP28: Packs four full-duplex lanes into a single QSFP form factor to deliver up to 103.1Gb/s aggregate throughput for high-density 100G links.
• 40km reach with FEC: Supports up to 40km on G.652 single-mode fiber with FEC enabled, enabling long-reach links between data center sites.
• 1310nm LAN-WDM transmitters: Four DFB-based LAN-WDM cooled transmitters provide stable optical performance across all channels for consistent signaling.
• Integrated monitoring (DDM): Digital diagnostics allow real-time monitoring of optical power, temperature, and other parameters to simplify troubleshooting and maintenance.
• Low power and wide temperature range: Operates from 0 to 70C with a single 3.3V supply and consumes under 3.8W, which helps control operating costs in dense deployments.
• Hot-pluggable convenience: The QSFP form factor and plug-and-play design make it easy to swap or upgrade transceivers without lengthy downtime.

Who It's For

The module is aimed at network engineers running medium to large data centers, colocation facilities, or enterprise campus links that require 100G connectivity over single-mode fiber up to tens of kilometers. It is especially suitable for rack-to-rack aggregation and client-side interconnections that need a low-power, monitored transceiver.

Those who should look elsewhere include teams that need extreme longer than 40km reach without FEC, custom wavelength planning beyond LAN-WDM, or specialized optics with novel connector formats - in those cases other ZR-class or DWDM solutions may be a better fit.

Pros & Cons

Pros

• Delivers 100G connectivity in a compact QSFP28 module with low power consumption under 3.8W.
• Supports up to 40km on standard G.652 SMF with FEC, covering most metro and inter-data-center links.
• Built-in DDM simplifies monitoring and proactive maintenance of optical links.
• Wide operating temperature and hot-pluggable design make it practical for dense installations.

Cons

• Without FEC the practical reach is limited to around 30km, so very long spans may require alternative optics.

Specifications

Form factor	QSFP28
Data rate	Up to 103.1Gb/s aggregate
Wavelength	1310nm LAN-WDM (4 channels)
Reach	Up to 30km without FEC; up to 40km with FEC on G.652 SMF
Connector	Duplex LC
Power	Single 3.3V, <3.8W
Operating case temperature	0 to 70C

Our Verdict

The QSFPTEK 100GBASE-ER4 QSFP28 module is a pragmatic choice for teams that need dependable 100G links over single-mode fiber with built-in monitoring and low power draw. It offers strong value for rack-to-rack and client-side interconnections up to 40km with FEC, and its hot-pluggable QSFP form factor keeps deployments and replacements simple.

Frequently Asked Questions

Does this module support monitoring?
Yes. It includes DDM support so administrators can monitor optical power, temperature, and other diagnostics in real time.

What reach can I expect on standard SMF?
Expect up to 30km without FEC and up to 40km with FEC on G.652 single-mode fiber according to the product specifications.

Is it compatible with common 100G QSFP ports?
Yes. It uses the QSFP28 form factor and is designed for standard QSFP-compatible 100G ports and typical client-side interconnections.