TP-Link TL-SM321B-2 Gigabit WDM Bi-Directional SFP Module Price in Kenya

The TP-Link TL-SM321B-2 is a 1000Base-BX WDM Bi-Directional SFP module designed for Gigabit Ethernet communication over a single strand of single-mode fibre.

It supports a 1.25Gbps optical data rate, transmits at 1310nm, receives at 1550nm, uses 9/125µm single-mode fibre, and supports transmission distances of up to 2 kilometres. The module uses an LC simplex interface and is designed to work with the complementary TP-Link TL-SM321A-2. 

TP-Link also specifies Digital Diagnostic Monitoring (DDM), SFP-MSA compatibility, SFF-8472-compatible diagnostics and hot-swappable operation, making the TL-SM321B-2 suitable for switches, routers, servers, media converters, CCTV systems and enterprise fibre networks. 

TP-Link TL-SM321B-2 Specifications

TP-Link's official product documentation confirms Tx1310nm/Rx1550nm, 2km reach, 9/125µm single-mode fibre, 1.25Gbps, LC simplex connectivity, DDM, SFP-MSA and hot-swappable operation. 

What Is the TP-Link TL-SM321B-2?

The TL-SM321B-2 is an optical transceiver that plugs into a compatible Gigabit SFP port.

Its main purpose is to create a full-duplex Gigabit Ethernet connection using only one single-mode fibre core.

A typical configuration is:

Switch A → TL-SM321A-2 → Single Fibre → TL-SM321B-2 → Switch B

TP-Link specifically states that the TL-SM321A-2 and TL-SM321B-2 should be used together as a pair for reliable communication between switches. 

What Does WDM Mean?

WDM stands for:

Wavelength Division Multiplexing

It allows different optical wavelengths to travel through the same fibre simultaneously.

For this TP-Link pair:

The wavelengths are complementary, allowing full-duplex communication through one fibre. 

What Does Bi-Directional Mean?

A Bi-Directional or BiDi SFP transmits and receives data through the same fibre strand.

A conventional duplex SFP usually requires:

Core 1 → Transmit

Core 2 → Receive

The TL-SM321B-2 instead uses:

One fibre → Transmit + Receive

with different wavelengths allocated to each direction.

This can significantly reduce the number of fibre cores required.

1000Base-BX Gigabit Ethernet

The TL-SM321B-2 uses the 1000Base-BX architecture.

TP-Link identifies it as a:

1000Base-BX WDM Bi-Directional SFP Module. 

It is suitable for:

• Gigabit switch uplinks

• Fibre media converters

• Building links

• CCTV fibre backbones

• Enterprise networks

• Campus networks

• Server connectivity

1.25Gbps Optical Data Rate

The TL-SM321B-2 operates at:

1.25Gbps

which corresponds to standard Gigabit Ethernet optical signalling.

TP-Link specifies a data rate of 1.25Gbps. 

1310nm Transmit Wavelength

The TL-SM321B-2 transmits at:

1310nm

Its complementary TL-SM321A-2 is designed to receive at 1310nm.

1550nm Receive Wavelength

The TL-SM321B-2 receives at:

1550nm

The TL-SM321A-2 transmits at 1550nm.

Therefore:

TL-SM321B-2:
Tx → 1310nm
Rx ← 1550nm

TL-SM321A-2:
Tx → 1550nm
Rx ← 1310nm

TP-Link confirms this wavelength arrangement in its module documentation. 

TL-SM321B-2 and TL-SM321A-2 Pairing

The correct pair is:

TL-SM321A-2 ↔ TL-SM321B-2

A typical network is:

Switch / Router
↓
TL-SM321A-2
↓
Single OS2 Fibre Strand
↓
TL-SM321B-2
↓
Switch / Router

The A-2 and B-2 modules should be paired because their transmit and receive wavelengths complement each other. 

Can Two TL-SM321B-2 Modules Work Together?

Normally, no.

Two TL-SM321B-2 modules would both:

Transmit at 1310nm

and

Receive at 1550nm

so their optical wavelength assignments would not complement one another.

Use:

TL-SM321A-2 + TL-SM321B-2

instead.

Up to 2KM Transmission Distance

The TL-SM321B-2 supports a maximum transmission distance of:

2 kilometres / 2,000 metres

over:

9/125µm single-mode fibre. 

This makes it particularly useful for short-to-medium-distance fibre links.

Why Use a 2KM BiDi SFP?

The 2km TL-SM321B-2 is suitable for networks where a 10km or 20km transceiver is unnecessary.

Common applications include:

• Office compounds

• Schools

• Universities

• Hospitals

• Hotels

• Industrial facilities

• CCTV networks

• Warehouses

• Estates

• Enterprise campuses

Single-Mode Fibre Support

The module is designed for:

9/125µm Single-Mode Fibre

TP-Link explicitly lists this fibre type for the TL-SM321B-2. 

OS2 single-mode cable is commonly suitable for this type of network when correctly terminated and tested.

One Fibre Strand

The TL-SM321B-2 requires:

One fibre core

rather than the two cores required by conventional duplex SFP modules.

This is one of its most important advantages.

LC Simplex Connector

The official current product page identifies the interface as:

LC Simplex

while TP-Link's broader SFP product guide describes the TL-SM321A-2/B-2 family as using LC/UPC Simplex. 

A typical patch cord would therefore be:

LC-LC Simplex Single-Mode Patch Cord

depending on the termination at the other end.

Watch TP-Link TL-SM321B-2 Video

https://youtu.be/kovGrcUcReo

The TP-Link TL-SM321B-2 provides a practical way to extend Gigabit Ethernet through existing single-mode fibre while using only one fibre core. Its WDM BiDi design makes it especially useful where spare fibre capacity is limited or where preserving additional cores for future services is important.

When paired with the TL-SM321A-2, the modules use complementary 1310nm and 1550nm wavelengths. This allows both directions of Gigabit traffic to travel at the same time through the same optical strand without requiring separate transmit and receive fibres. 

With a rated distance of up to 2km, DDM monitoring and a hot-swappable SFP form factor, the TL-SM321B-2 is particularly suitable for local campus networks, CCTV installations, enterprise compounds and building-to-building fibre connections. 

Digital Diagnostic Monitoring – DDM

The TL-SM321B-2 supports:

Digital Diagnostic Monitoring

TP-Link states that its DDM implementation is compatible with:

SFF-8472. 

Depending on the host switch, DDM can provide information about:

• Transmit optical power

• Receive optical power

• Operating temperature

• Transceiver current

• Module operating condition

Why DDM Matters

DDM can help technicians troubleshoot issues such as:

• Low received optical power

• Dirty connectors

• Poor fibre splices

• Excessive fibre attenuation

• Fibre bends

• Module temperature problems

It can be especially useful on managed switches that expose optical diagnostics through their management interface.

SFP-MSA Compatibility

The TL-SM321B-2 supports:

SFP-MSA

or the:

Small Form-factor Pluggable Multi-Source Agreement

TP-Link explicitly states that the module was developed in accordance with SFP-MSA requirements. 

Host-device compatibility should still be verified because some network equipment applies vendor-specific SFP restrictions.

Hot-Swappable Design

The module supports:

Hot Swap

operation.

This means it can be inserted or removed from compatible SFP equipment without replacing the entire switch, router or media converter.

TL-SM321B-2 for Switch-to-Switch Fibre

A common installation is:

Access Switch
↓
TL-SM321A-2
↓
Single Fibre
↓
TL-SM321B-2
↓
Core Switch

This can create a Gigabit link between network cabinets or buildings.

TL-SM321B-2 for Building-to-Building Fibre

The module is suitable for building links within approximately 2km.

Typical installations include:

• Office blocks

• Schools

• Hospitals

• Hotels

• Factories

• Warehouses

• Universities

• Government facilities

TL-SM321B-2 for CCTV Networks

A CCTV configuration may look like:

IP Cameras → PoE Switch → TL-SM321A-2 → Single Fibre → TL-SM321B-2 → Core Switch → NVR

Using fibre can help extend the network beyond normal copper Ethernet distance limitations.

TL-SM321B-2 for Campus Networks

The 2km range makes it useful for campus environments where several nearby buildings need Gigabit connectivity.

Suitable locations include:

• Universities

• Colleges

• Schools

• Hospitals

• Business parks

• Government compounds

• Residential estates

TL-SM321B-2 for Enterprise Networks

Businesses can use the module for:

• Network cabinet links

• Building uplinks

• CCTV backbones

• Server-room connections

• Warehouse connectivity

• Remote office links

• Fibre distribution

TL-SM321B-2 vs TL-SM321A-2

The two modules are complementary.

TP-Link's installation guide confirms both their complementary wavelength assignment and 2km rating. 

TL-SM321B-2 vs TL-SM321B

The main difference is distance.

TP-Link's current switch documentation lists the B-2 at 2km and the standard B at 20km. 

TL-SM321B-2 vs TL-SM311LS

TL-SM321B-2 vs TL-SM311LM

TL-SM321B-2 vs 20KM BiDi Module

Why Not Use a 20KM SFP Everywhere?

Longer optical reach is not automatically better.

A fibre design should consider:

• Actual route distance

• Transmit power

• Receiver sensitivity

• Receiver overload

• Fibre attenuation

• Connector loss

• Splice loss

• Engineering margin

For a short route, a properly selected short-range module can provide a more appropriate optical design.

Fibre Core Conservation

BiDi technology can make much better use of limited fibre capacity.

For example, an 8-core cable using conventional duplex SFPs can support up to:

4 duplex optical links

if every link consumes two cores.

With BiDi:

up to 8 single-fibre links

may be possible depending on topology.

Optical Link Budget

Although the TL-SM321B-2 is rated for up to 2km, actual link performance depends on total optical loss.

Loss comes from:

• Fibre attenuation

• Fusion splices

• Patch cords

• Adapters

• Connectors

• Fibre bends

• Dirty ferrules

Testing TL-SM321B-2 Links

Optical Power Meter

An Optical Power Meter can measure optical signal levels at the receiving end.

OTDR

An OTDR can help locate:

• Fibre breaks

• High-loss splices

• Connector events

• Fibre length

• Macrobends

• Excessive attenuation

Visual Fault Locator

A VFL can help with basic continuity checks and visible faults on shorter routes.

Fibre Connector Cleaning

Always clean the LC connector before making the connection.

Dirty fibre connectors can cause:

• High optical attenuation

• Unstable links

• Low Rx readings

• Link failure

• Packet loss

Operating Temperature

TP-Link specifies:

0°C to 70°C

for normal operation and approximately:

-40°C to 85°C

for storage. 

Dimensions

The TL-SM321B-2 measures approximately:

55.4 × 14.6 × 12.9mm. 

Power Supply

The module operates from:

3.3V

through the compatible SFP interface.

TP-Link TL-SM321B-2 Price in Kenya

The TP-Link TL-SM321B-2 price in Kenya varies depending on supplier, stock availability, VAT, warranty and quantity.

A current Senetic Kenya listing shows approximately:

KES 1,897.13 excluding VAT

or:

KES 2,200.67 including VAT. 

However, that same supplier page currently shows a 1,000m distance field, which conflicts with TP-Link's official 2km specification. For technical specifications, TP-Link's official documentation should be treated as the authoritative source. 

Approximate TL-SM321B-2 Market Price in Kenya

Third-party prices may change without notice and do not represent a fixed Fiber Optics Kenya selling price.

Contact Fiber Optics Kenya for the current TP-Link TL-SM321B-2 price and stock availability.

What Affects TL-SM321B-2 Price in Kenya?

Pricing can vary according to:

• Distributor

• Stock availability

• Warranty

• VAT

• Quantity ordered

• Import cost

• Hardware revision

• Whether TL-SM321A-2 is included

Is TL-SM321A-2 Included?

Normally, no.

TP-Link specifies the package contents as:

TL-SM321B-2 SFP Module + Installation Guide. 

Therefore, the complementary TL-SM321A-2 is normally purchased separately unless a supplier specifically offers them as a pair.

How to Choose the Correct TL-SM321B-2

Before purchasing, confirm:

1. Your equipment has a compatible Gigabit SFP port.

2. The installed fibre is 9/125µm single mode.

3. Only one fibre core is available or preferred.

4. The link distance is within approximately 2km.

5. The opposite side uses TL-SM321A-2.

6. The connector is LC simplex.

7. The switch supports the module.

8. DDM is supported if optical monitoring is required.

Recommended Accessories

Frequently Asked Questions About TP-Link TL-SM321B-2

What is the TP-Link TL-SM321B-2?

It is a 1000Base-BX WDM Bi-Directional Gigabit SFP transceiver. 

What speed does it support?

It supports Gigabit Ethernet with a 1.25Gbps optical data rate. 

What wavelength does TL-SM321B-2 transmit?

1310nm.

What wavelength does it receive?

1550nm. 

Which module pairs with TL-SM321B-2?

TP-Link TL-SM321A-2. 

What does TL-SM321A-2 transmit?

1550nm.

What does TL-SM321A-2 receive?

1310nm. 

Can two TL-SM321B-2 modules connect directly?

Normally no. A complementary A-2/B-2 wavelength pair is required.

What is the maximum distance?

Up to 2km according to TP-Link's official specification. 

Why does one retailer say 1km?

One current Kenya listing shows 1,000m, but TP-Link's official documentation specifies 2km, so the manufacturer's specification should be used for network design. 

What fibre type does it use?

9/125µm single-mode fibre.

Is it suitable for OS2 fibre?

Yes, when the OS2 cable and termination are compatible with the module.

How many fibre strands are required?

One.

Is it BiDi?

Yes.

What does BiDi mean?

Bidirectional communication over a single fibre strand.

What does WDM mean?

Wavelength Division Multiplexing.

What connector does it use?

LC Simplex. 

Is it LC/UPC?

TP-Link's broader module documentation lists the A-2/B-2 family as LC/UPC simplex. 

Does it need a duplex patch cord?

No. A simplex fibre connection is used.

Does it support DDM?

Yes.

What does DDM do?

It provides real-time diagnostic information about the SFP when supported by the host device.

Is DDM compatible with SFF-8472?

Yes. 

Is it SFP-MSA compatible?

Yes. 

Is it hot-swappable?

Yes. 

What voltage does it use?

3.3V. 

Can it connect two switches?

Yes, using the correct complementary module.

Can it connect two buildings?

Yes, provided the route remains within the optical specification.

Can it work over 500 metres?

Yes, provided optical power remains within specification.

Can it work over 1km?

Yes.

Can it work over 2km?

Yes, subject to total link loss.

Can it work over 5km?

It is not rated for 5km. Use an appropriate longer-range BiDi SFP.

Can it work over 20km?

No. Use TL-SM321A/TL-SM321B or another suitable 20km pair.

Is it suitable for CCTV networks?

Yes.

Is it suitable for campus networks?

Yes.

Is it suitable for enterprise networks?

Yes.

Is it suitable for schools?

Yes.

Is it suitable for hospitals?

Yes.

Is it suitable for warehouses?

Yes.

Is it suitable for ISPs?

Yes, where a 2km point-to-point Gigabit BiDi link is appropriate.

Is it a GPON SFP?

No.

Is it an EPON SFP?

No.

Can it replace an EPON PX20 module?

No. They serve different network architectures.

Is TL-SM321B-2 the same as TL-SM321B?

No. TL-SM321B-2 is rated for 2km, while TL-SM321B is a longer-range model rated up to 20km in current TP-Link documentation. 

Is TL-SM321B-2 the same as TL-SM311LS?

No. TL-SM321B-2 uses one fibre with WDM BiDi, while TL-SM311LS uses conventional duplex fibre.

Is it a 10G module?

No.

Is it SFP+?

No. It is a standard Gigabit SFP.

Can it provide 10Gbps?

No.

Can I use LC-LC simplex patch cord?

Yes.

Can I use LC-SC simplex fibre?

Yes, provided the fibre type and connector polish are compatible.

Should I clean the connector before installation?

Yes.

Can a dirty connector stop the SFP from linking?

Yes.

Can an Optical Power Meter test the link?

Yes.

Can an OTDR test the fibre?

Yes.

What is the operating temperature?

0°C to 70°C. 

What is the storage temperature?

Approximately -40°C to 85°C. 

What are its dimensions?

Approximately 55.4 × 14.6 × 12.9mm. 

What is the TL-SM321B-2 price in Kenya?

A current Senetic Kenya example is around KES 1,897 excluding VAT or KES 2,201 including VAT, but prices vary.

Is TL-SM321A-2 included?

Normally no.

Do you supply TL-SM321A-2/TL-SM321B-2 pairs?

Yes, subject to stock availability.

Do you supply 20KM BiDi SFP modules?

Yes.

Do you supply 40KM BiDi SFP modules?

Yes.

Do you supply LC simplex patch cords?

Yes.

Do you supply OS2 fibre?

Yes.

Do you supply media converters?

Yes.

Do you supply Optical Power Meters?

Yes.

Do you supply OTDRs?

Yes.

Can businesses and ISPs order in bulk?

Yes. Bulk supply is suitable for enterprises, CCTV installers, campuses, fibre contractors and ISPs.

Do you deliver outside Nairobi?

Yes. Fiber Optics Kenya supplies fibre optic and networking equipment throughout Kenya.

Why Buy TP-Link TL-SM321B-2 from Fiber Optics Kenya?

Contact Fiber Optics Kenya

Fiber Optics Kenya
Lyric House, 7th Floor Room S9
Kimathi Street, Nairobi

Phone: +254 704 991 492
Email: info@fibreopticskenya.co.ke

The TP-Link TL-SM321B-2 Gigabit WDM Bi-Directional SFP Module is designed for short-to-medium-distance Gigabit fibre connections over one 9/125µm single-mode fibre strand. It supports 1.25Gbps, Tx1310nm/Rx1550nm, LC simplex connectivity, DDM, SFP-MSA and hot-swappable operation, with an official maximum reach of 2km. 

When paired with the complementary TL-SM321A-2, the two modules create a full-duplex Gigabit Ethernet path using only one fibre core. This makes them especially useful for campus networks, building-to-building links, CCTV systems, enterprise compounds, schools, hospitals and other fibre networks where preserving available cores matters. 

A current Kenyan market example is approximately KES 1,897 excluding VAT or KES 2,201 including VAT, although prices and availability can change. 

Contact Fiber Optics Kenya for the current TP-Link TL-SM321B-2 price in Kenya, TL-SM321A-2/TL-SM321B-2 pairs, 20KM and 40KM BiDi SFP modules, LC simplex patch cords, media converters, fibre testing equipment, bulk orders and nationwide delivery.