eSFP-850nm-1000Base-Sx

eSFP-850nm-1000Base-Sx is an enhanced small form-factor pluggable module, operating at 850 nm over a rated reach of 0.55 km. It is the part that turns electrical signals into light at one end of a fibre and back at the other, and it is the component most often got wrong on an order, because two modules can look identical and be entirely incompatible.

It is specified at 1.25 Gbit/s.

The number that decides whether this will actually work: the optical power budget. Transmit power is -10 to -2.5 dBm and receiver sensitivity is -17 dBm, so the budget is -10 minus -17, which is 7 dB. That is the total loss the path can have before the link stops working. Over 0.55 km of multimode fibre at this wavelength, at roughly 3 dB per kilometre, the fibre itself accounts for about 1.7 dB. That leaves around 5.3 dB for connectors, splices and ageing, which is workable but not generous: on a path with several patch panels, measure the real loss rather than trusting the distance.

This is a multimode module and it is not interchangeable with a single-mode one. Multimode fibre has a much wider core, so a single-mode module will not couple into it properly and a multimode module cannot drive a single-mode span. On multimode the limiting factor is usually not loss but modal bandwidth, which is why reaches are quoted in hundreds of metres rather than tens of kilometres, and why the fibre’s OM grade matters as much as its length.

The module is rated from -40 to 85 degrees Celsius, which is an industrial temperature range rather than a commercial one. That matters if it is going into a street cabinet, a trackside enclosure, a tower-mounted unit or anywhere else without climate control. Commercial-temperature optics in those positions tend to work until the first hot summer or hard frost, and then produce errors that are very hard to diagnose because they come and go with the weather.

The optical connector is LC. Worth confirming against the patch leads already on site.

The RTN 310 is a Huawei microwave platform, and its lifecycle status is genuinely unclear. Huawei’s RTN line as a whole is still an active product family, but the position of this particular model could not be established: Huawei’s lifecycle database sits behind a login and model-level end-of-sale and end-of-support dates are not published openly.

So this page will not tell you the platform is current and will not tell you it is finished, because neither can be checked from outside. If that distinction matters to your purchase, and on microwave it often does because licensed-band links tend to live for a decade, ask us to confirm it with Huawei before you commit.

One thing to raise before you order. Huawei transmission equipment generally expects Huawei-coded optics, and a module without the right vendor coding may be refused outright or raise a persistent alarm even when it is electrically identical to the correct part. We supply coded modules for that reason. Tell us the platform, the port, the fibre you have and the distance, and we will confirm this is the right module or point you at the one that is.

Green Code Technologies supplies Huawei optical modules alongside the transmission equipment they fit. We are a supplier of Huawei alongside HPE, Dell, Cisco, Samsung and Netgear, and we would rather confirm a part against Huawei’s own documentation than sell you the wrong one, which on RTN 310 equipment is worth doing. Send us the platform and port at each end, the fibre you have and the distance and we will come back with a straight answer.