Network transceiver module Mikrotik S-3553LC20D

The Mikrotik S-3553LC20D is a pair of single-mode SFP network transceiver modules designed for 1.25 Gbit/s (1250 Mbit/s) fiber links. Each pair includes two complementary modules: one operating at T1310nm/R1550nm and the other at T1550nm/R1310nm, enabling bidirectional transmission over a single fiber. With LC connectors and support for Digital Diagnostics Monitoring (DDM), these modules provide fiber connectivity for links up to 20,000 meters and are compatible with a variety of MikroTik switches and routers as well as many third-party SFP-capable devices.

Advantages

The S-3553LC20D pair offers a straightforward solution for extending fiber connections up to 20 km using single-mode optics and LC connectors. DDM support allows monitoring of optical parameters such as temperature and optical power for improved link maintenance. Compatibility with multiple MikroTik models and non-MikroTik SFP ports provides deployment flexibility in mixed-vendor environments. The modules’ single-mode design and standardized 1.25 Gbit/s rate make them suitable for common access and aggregation use cases.

Suitable for

• Extending network links between buildings or across campus using single-mode fiber
• Upgrading switch or router SFP ports to support 1.25 Gbit/s fiber connectivity
• Mixed-vendor environments where interoperable SFP modules are required
• Monitoring optical link health via DDM for preventive maintenance

Key specifications

• Data rate: 1250 Mbit/s (1.25 Gbit/s)
• Maximum transfer distance: up to 20,000 m (20 km) over single-mode fiber
• Connector type: LC duplex
• Optical wavelengths: T1310nm/R1550nm and T1550nm/R1310nm (bidirectional pair)
• Optical mode: Single-mode
• DDM: Digital Diagnostics Monitoring supported

How to use

Install one module in the SFP slot of each device that will form the fiber link, ensuring the correct orientation and secure seating in the SFP cage. Use single-mode LC fiber patch cords or pigtails and verify that the pair’s transmit and receive wavelengths are matched for bidirectional operation on the same fiber. After physical installation, check link status on the connected devices and enable or review DDM readings where supported to confirm optical power and diagnostic parameters. Follow standard ESD precautions when handling optical transceivers.

Recommendations

Use clean single-mode LC connectors and maintain proper fiber bend radii to preserve signal quality. Validate fiber continuity and loss with appropriate test equipment before relying on the link for production traffic. When deploying in mixed hardware environments, confirm SFP interoperability in a test setup if device-specific compatibility lists are not available.