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Small rectangular SFP transceiver module with silver metal casing and black LC simplex port visible

TP-Link

TP-Link TL-SM321A 1000Base-BX WDM Bi-Directional Gigabit Single-Mode SFP Transceiver

SKU CH-MD01-32GG5 MPN TL-SM321A

Single-mode SFP module delivers bidirectional gigabit links over one fiber up to 20 km with LC simplex connector and DDM monitoring

  • StandardsIEEE 802.3z, TCP/IP
  • WavelengthTX: 1550nm / RX: 1310nm
  • Fiber CableSingle-mode Optical Fiber
  • ProtocolsCSMA/CD, TCP/IP
  • PortsLC
  • Transfer Rate1.25Gbps
  • Bi-directional WDM links switches over one single-mode fibre
  • 20 km reach on 9/125 µm SMF extends campus networks
  • Hot-swappable SFP-MSA design fits TP-Link JetStream ports
  • DDM to SFF-8472 gives live optical power and temperature data
  • LC simplex connector carries 1.25 Gbps full-duplex traffic

Single-fibre bidirectional SFP

The TL-SM321A is a 1000Base-BX WDM transceiver that sends and receives gigabit data on one single-mode fibre strand. It targets network engineers extending links between switches, storage arrays or servers up to 20 km using 9/125 µm cable. The module plugs into any SFP-MSA port and pairs with the TL-SM321B to form a full-duplex path.

Thermals and power

Operating temperature spans 0 °C to 70 °C with humidity tolerance of 10 % to 90 % non-condensing. The hot-swappable design allows insertion or removal without powering down the host device, so service interruptions are avoided. Power draw follows the SFP-MSA envelope and the integrated DDM function reports real-time temperature, bias current and optical levels for proactive monitoring.

Deciding specification

TX wavelength is 1550 nm and RX wavelength is 1310 nm, delivering 1.25 Gbps over an LC simplex connector. This wavelength pairing only works when the opposite end uses the complementary 1310 nm TX / 1550 nm RX module. Buyers who need a different wavelength plan or multimode fibre cannot use this transceiver.

Highlights

  • Bi-directional WDM links switches over one single-mode fibre
  • 20 km reach on 9/125 µm SMF extends campus networks
  • Hot-swappable SFP-MSA design fits TP-Link JetStream ports
  • DDM to SFF-8472 gives live optical power and temperature data
  • LC simplex connector carries 1.25 Gbps full-duplex traffic

Specifications

BrandTP-Link
ModelTL-SM321A
StandardsIEEE 802.3z, TCP/IP
WavelengthTX: 1550nm / RX: 1310nm
Fiber CableSingle-mode Optical Fiber
ProtocolsCSMA/CD, TCP/IP
PortsLC
Transfer Rate1.25Gbps
Temperature0° ~ 70° C
Humidity10%~90% non-condensing
FeatureSingle-mode SFP Module, WDM Bi-Directional communication on a single fiber.
Work with TL-SM321B as a pair and create a full-duplex gigabit path between your switches, storage devices, and server.
Wavelength: Tx 1550nm, Rx 1310nm. Data Rate: 1.25Gbps. Port Type: LC Simplex.
Always keep the protective dust plug on the SFP's optical bores until you are ready to make a connection.
Compatible with all SFP ports on TP-Link product including JetStream switches, and media converter MC220L.
Developed in accordance with the Small Form Pluggable Multi-Source Agreement (SFP-MSA), TL-SM321A uses
Package ContentsSFP Module TL-SM321A
Installation Guide
Shipping weight0.23 kg
Package size229 × 152 × 51 mm

Questions about this item

How do I install the TL-SM321A in an SFP port, and what is the step people often miss?

Insert the module until it clicks, then remove the dust plug from the LC bore only when the fiber patch cord is ready to connect. The guide stresses keeping the plug on until that moment to avoid contaminating the optical interface.

What ongoing maintenance or replacement will the TL-SM321A need?

No scheduled maintenance is required. If the DDM-reported Tx or Rx optical power drifts outside the expected range for the 20 km 9/125 µm link, or if the operating temperature exceeds 70 °C, replace the module.

What limit appears first when the TL-SM321A runs continuously at full load?

The 70 °C maximum operating temperature is the first sustained-use constraint. DDM lets you monitor the real-time case temperature so you can verify the host switch provides adequate airflow before thermal limits are reached.

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