TP-Link Omada Gigabit WDM Bi-Directional SFP Module 20 km, 1550 nm TX / 1310 nm RX

TP-Link Omada 1000Base-BX WDM Bi-Directional SFP Module (TL-SM321A) - 5 Years Local Warranty

The TL-SM321A is the "A" half of TP-Link's 20 km bi-directional Gigabit pair. It transmits on 1550 nm and receives on 1310 nm, sending and receiving over a single strand of single-mode fibre instead of the usual two. Where fibre strands are scarce, leased, or already fully patched, that halves what a Gigabit link consumes.

One Fibre Strand Instead of Two

A conventional duplex transceiver needs two strands: one to transmit, one to receive. A WDM bi-directional module puts both directions on one strand at different wavelengths, separated optically at each end. On a leased dark-fibre link where strands are billed individually, or in a building where the riser bundle is already full, that is the difference between a project that proceeds and one that waits for a new pull. The TL-SM321A uses an LC simplex connector, reflecting the single-strand design.

Twenty Kilometres at Full Gigabit

TP-Link publishes a maximum cable length of 20 km over 9/125 µm single-mode fibre for the TL-SM321A, running at the full 1.25 Gbps data rate under IEEE 802.3z. That reach covers most Singapore inter-site links in a single hop. If your run is inside 2 km, the TL-SM321A-2 is the shorter-reach equivalent of this same wavelength arrangement, and the two are not interchangeable — reach and optical budget differ.

It Must Be Paired With a TL-SM321B

Because the two directions use different wavelengths, the ends of a WDM link are not identical. The TL-SM321A transmits 1550 nm and receives 1310 nm; the TL-SM321B does the reverse. One of each is needed for a working link — two A modules will not talk to each other, and neither will two B modules. When ordering, count your links, not your ports: one A and one B per link, and keep the 20 km and 2 km families separate.

DDM, MSA Compliance and Hot Swapping

The module supports Digital Diagnostic Monitoring, so a host switch can read live optical transmit and receive power, temperature and supply voltage — particularly useful on a long single-strand link where a fault is not convenient to reach. It is SFP-MSA compliant and hot-swappable, fitting any standard Gigabit SFP cage and replaceable without taking the switch down. Power is 3.3 V from the host, and the module measures 55.4 x 14.6 x 12.9 mm.

Ideal For

Singapore businesses running Gigabit links over leased or scarce single-mode fibre, and IT teams connecting remote sites, blocks or cabinets where only one strand is available. Supplied by SourceIT with local Singapore warranty, GST invoice and project pricing on request.