TP-Link SM321A | 1000Base-BX WDM Bi-Directional SFP Module (1550nm TX / 1310nm RX) - 20KM
SKU: SM321ANetworking › Network Accessories
Please enquire before ordering
The distributor has not yet confirmed the latest price and availability (last checked Jul 3, 2026)
092-251-4017Awaiting stock confirmationManufacturer's warranty
GenuineFree delivery from ฿5,000Tax invoice
Dual-fiber WDM SFP module uses a single fiber optic cable to transmit data in both directions simultaneously. Supports up to 20 km distance and works immediately with TP-Link switches or routers.
Key features
- Transmits data in both directions simultaneously using a single fiber optic cable.
- Supports a maximum distance of 20 km on Single-Mode cable
- Uses different wavelengths: TX 1550 nm / RX 1310 nm.
- Supports Digital Diagnostic Monitoring (DDM) for real-time status monitoring.
- Designed for hot-swappable operation.
Product description
The TP-Link SM321A module is a WDM duplex (Bi-Directional) fiber optic networking solution that uses a single fiber cable to transmit both incoming and outgoing data by utilizing different wavelengths: 1550 nm for transmission (TX) and 1310 nm for reception (RX), reducing fiber cable usage by up to half compared to traditional systems. This module supports a maximum speed of 1.25 Gbps and can transmit signals up to 20 kilometers over 9/125 μm Single-Mode fiber optic cable, making it ideal for inter-building connections, data centers, or enterprise networks requiring high stability and long-distance connectivity. The module supports the SFP-MSA standard and features hot-swappable capability for convenient maintenance.
More features
- Supports SFP-MSA standard, compatible with multi-vendor devices.
- Compact size: 2.2 x 0.6 x 0.5 inches, fits standard SFP slots.
- Operates in temperatures from 0–70 °C, suitable for indoor and outdoor use.
Pros and limitations
Pros
- Reduces fiber cabling costs by half using parallel WDM technology.
- Supports up to 20 kilometers transmission distance over 9/125 μm Single-Mode fiber.
- Features DDM for real-time monitoring of temperature, voltage, and optical power.
- Designed for hot swapping, allowing replacement without powering down the device.
- Supports SFP-MSA standard, ensuring compatibility with multi-vendor equipment.
Limitations
- Must be used with TL-SM321B module to achieve full performance.
- Not supported for short-range operation beyond 2 km over the same fiber (depends on model).
Who it is for
Ideal for users needing to extend long-distance network connectivity between buildings, data centers, or branch offices using a single fiber to reduce costs and improve data transmission efficiency.
Connectivity
LC Connector
Specifications (21)
- Data Rate
- 1.25 Gbps
- Port Type
- LC Simplex
- Cable Type
- Single-Mode Fiber
- Fiber Type
- 9/125 μm Single-Mode
- DDM Support
- Yes
- Form Factor
- SFP
- Power Supply
- 3.3 V
- Hot Swappable
- Yes
- Wave Length RX
- 1310 nm
- Wave Length TX
- 1550 nm
- Max Cable Length
- 20 KM
- Storage Humidity
- 5–90% RH, Non-Condensing
- Safety & Emission
- FCC, CE
- Compatibility Pair
- TL-SM321B
- Operating Humidity
- 10–90% RH, Non-Condensing
- Storage Temperature
- -40–85 °C (-40–185 °F)
- Operating Temperature
- 0–70 °C (32–158 °F)
- SFP-MSA Compatibility
- Yes
- Dimensions (W x D x H)
- 2.2*0.6*0.5 in (55.4*14.6*12.9 mm)
- Standards and Protocols
- IEEE 802.3z, TCP/IP
- Digital Diagnostic Monitoring
- Yes
Datasheets and manuals straight from the manufacturer — select a document to open or download it.
13 questions
Frequently asked questions about this product
Compiled from manufacturer information
Which TP-Link switch models is the SM321A module compatible with?
This module supports TP-Link switches with SFP ports that support the 1000Base-BX standard, such as mid-to-high-end Omada models, or other switches that support SFP-MSA, especially those using Bi-Directional WDM systems
Does it require a paired module? Can SM321A be used with SM321B?
Yes, this module must be used in pairs to communicate properly. Use the SM321A transmitting at 1550 nm with the SM321B receiving at 1550 nm to ensure correct operation as a pair.
Can it really achieve 20 km distance?
Yes, this module supports signal transmission up to 20 kilometers over 9/125 μm Single-Mode fiber optic cable, provided it is used with a compatible module and the cable is undamaged or not severely bent
Does it have real-time status monitoring features?
Yes, this module supports Digital Diagnostic Monitoring (DDM), which allows real-time monitoring of parameters such as voltage, temperature, transmit and receive optical power through network management systems.
Can the module be replaced while the device is running?
Yes, this module supports hot-swappable operation, meaning it can be removed or installed without shutting down the main device, reducing system downtime during maintenance.
Is it compatible with standard fiber optic cables?
Not all cables — only 9/125 μm Single-Mode fiber optic cable is required. Using Multi-Mode cable will result in inefficient signal transmission
How much power does this module consume?
The module operates at 3.3 V. Power consumption per hour is not specified, but it is considered low-power according to SFP standards.
What are the operating environmental conditions?
Operates in temperatures from 0–70 °C and humidity of 10–90% RH (non-condensing). Can be stored at -40–85 °C and humidity of 5–90% RH.
Is it in stock?
We are confirming the latest stock and price of the TP-Link SM321A | 1000Base-BX WDM Bi-Directional SFP Module (1550nm TX / 1310nm RX) - 20KM with the distributor. Please contact us before ordering at 092-251-4017 or sales@gist.co.th.
How much does it cost?
The distributor has not yet confirmed the latest price and availability. Please contact us before ordering at 092-251-4017 or sales@gist.co.th.
How long is the warranty?
The warranty follows the manufacturer's terms for each model; ask our sales team for the warranty period of this model. To make a warranty claim, call 092-251-4017 or 065-523-5262, or email sales@gist.co.th (Mon–Fri 9:00–18:00), then send the product with your order number to our head office, or bring it to the head office in person.
How long does delivery take?
Orders placed before 12:00 on a business day are delivered within 1–3 business days (Bangkok and vicinity) or 2–5 business days (other provinces). Free delivery on orders of ฿5,000 or more (a ฿150 delivery fee applies below this amount).
Is it genuine?
Genuine products sourced from distributors in Thailand, covered by the manufacturer's warranty. Full tax invoices are available.
Didn't find the answer you need?
Loading reviews…
Genuine products
Sourced from distributors in Thailand and covered by the manufacturer's warranty
Warranty period
According to the manufacturer's terms for each model
Covered by the manufacturer's warranty; you can make claims through GIST
Claims through GIST
Ship the product to our head office or bring it in person
Warranty conditions
- A receipt or other proof of purchase is required
- The product must not have been modified or altered
- Damage caused by misuse is not covered by the warranty
- To make a warranty claim, call 092-251-4017 or 065-523-5262, or email sales@gist.co.th (Mon–Fri 9:00–18:00), then send the product with your order number to our head office, or bring it to the head office in person.Head office: 554 Sky Nine Center, Floor 12A, Room 554/62, Asok-Din Daeng Road, Din Daeng Subdistrict, Din Daeng District, Bangkok 10400
More in Network Accessories
