TP-Link TL-SM321A/B 1.25G BIDI SFP Module Pair - 10-20KM Reliable Link

In this review of the TP-Link TL-SM321A and TL-SM321B compatible pair, the bottom line is simple: this Jeirdus SFP BIDI transceiver set is for network engineers and IT teams who need a cost-effective, tested bidirectional fiber link over a single LC connector. The reviewer found the modules deliver the expected 1.25 Gb/s performance for up to 20 km and simplify cabling by using WDM over a single strand. Because Jeirdus validates compatibility in its lab and individually tests each unit, the primary reason to buy is dependable interoperability with TP-Link and Cisco equipment without buying original-brand modules.

Key Features

• Bidirectional WDM: Uses separate TX/RX wavelengths (TX1310nm/RX1550nm and vice versa) so a single LC fiber carries both directions, reducing cabling.
• Carrier-class compatibility: Designed to meet the coding requirements for TP-Link TL-SM321A and TL-SM321B and compatible with Cisco switches for straightforward plug-and-play.
• Tested quality: Each transceiver is individually tested in Jeirdus labs to ensure interoperability and reduce deployment issues.
• Range and speed: Supports 1000BASE-BX and 1.25 Gb/s operation for links up to 20 km, suitable for many campus and metro applications.
• Durability and warranty: Built from 100% new materials with CE and FCC compliance and backed by a 3 year replacement plus lifetime warranty for long-term peace of mind.

Who It's For

The ideal buyer is an IT professional, systems integrator, or small data center manager who needs a reliable, lower-cost alternative to original-brand SFP modules for point-to-point fiber links up to 20 km. It is particularly useful when single-fiber routing or limited conduit space makes simplex LC transceivers the preferred choice.

Those who should look elsewhere include users requiring higher speeds than 1.25 Gb/s or multimode fiber transceivers for short-reach links, and buyers who must use manufacturer-branded parts for vendor-managed warranties or certified equipment lists.

Pros & Cons

Pros

• Compatible with TP-Link TL-SM321A/B and Cisco devices, easing replacements and upgrades.
• Single LC WDM reduces fiber infrastructure needs and simplifies installation.
• Individually tested modules and regulatory compliance increase deployment confidence.

Cons

• Limited to 1.25 Gb/s operation, so not suitable where multi-gigabit links are required.

Specifications

Our Verdict

The Jeirdus-compatible TP-Link TL-SM321A/TL-SM321B pair is a practical, cost-conscious choice for network teams who need proven bidirectional SFP transceivers for single-fiber links up to 20 km. With lab compatibility testing, individual unit checks, and a robust warranty, it offers strong value for deployments that do not require multi-gigabit speeds.

Frequently Asked Questions

Are these modules compatible with TP-Link switches?
Yes. Jeirdus states these SFPs are designed for TP-Link TL-SM321A and TL-SM321B and are tested for coding compatibility.

What fiber connector and wavelengths do they use?
They use a single LC connector and operate as a BIDI pair with 1310 nm and 1550 nm wavelengths in opposite directions.

How far will the link reach?
The modules support links up to 20 km at 1.25 Gb/s under the specified standards.