Tag Archives: fiber transceiver

How to Understand Tx Power vs. Rx Power of a Fiber Transceiver?

As we all know, single mode fiber optic transceiver is designed for long distance data transmission and multimode fiber optic transceiver is for short distance link. How to calculate the specific distance that a fiber optic transceiver can support at a certain occasion? What factors are crucial to the transmission distance? Do you have any idea of Tx (transmit) power and Rx (receive) power level of a fiber optic transceiver? This article will show you by introducing 10GBASE-SR SFP+ and 10GBASE-LR SFP module.

Tx Power and Rx Power of a Fiber Transceiver

First, let’s understand the most two important factors of the fiber optic transceiver: Tx power and Rx power. The optical Tx power is the signal level leaving that device and it should be within the transmitter power range. The Rx power is the incoming signal level being received from the far end device and it should fall within the receive power range.

10GBASE-SR SFP+ is a multimode fiber transceiver and can support the distance of 300 m over OM3 multimode fiber patch cable. While 10GBASE-LR SFP module is a single mode type and can run the network distance up to 10 km over single mode fiber patch cords. Before purchasing 10GBASE SFP+ module, you must carefully read the product details. The following lists the product details about 10GBASE-SR SFP+ and 10GBASE-LR SFP module from Fiberstore. As showing below, Tx power of this Cisco compatible 10GBASE-SR SFP+ is between -7.3 dBm and -1 dBm. The maximum receive power is below -11.1 dBm. With regard to Cisco compatible 10GBASE-LR SFP module, Tx power is from -8.2 to 0.5 dBm and the maximum Rx power is -14.4 dBm.

Tx Power and Rx Power of 10GBASE-SR SFP+

Tx Power and Rx Power of 10GBASE-SR

Tx Power and Rx Power of 10GBASE-LR SFP+ Module
Tx Power and Rx Power of 10GBASE-LR
Tx Power and Rx Power VS. Optical Power Budget

To calculate the specific distance of a fiber optic transceiver, we need to know its optical power budget (maximum allowable loss).

Optical power budget = Tx power – Rx power

Therefore, according to the Tx power and Rx power, we can calculate the maximum allowable loss of 10GBASE-SR SFP+ and 10GBASE-LR SFP module.

Optical Power Budget of 10GBASE-SR SFP+

Min Tx Power = -7.3 dBm
Max Rx Power = -11.1 dBm
Optical power budget (maximum allowable loss) = (-7.3 dBm) – (-11.1 dBm)=3.4 dBm

Optical Power Budget of 10GBASE-LR SFP+ Module

Min Tx Power = -8.2dBm
Max Rx Power = -14.4 dBm
Optical power budget (maximum allowable loss) = (-8.2 dBm) – (-14.4 dBm)=6.2 dBm

Tx Power and Rx Power VS. Transmission Distance

Except optical power budget, we have to consider other factors including the link length, fiber optical connectivity components, fusion splicing points and some unpredictable fiber attenuation caused by fiber patch cable bending (usually the attenuation is about 3 dB). The loss of each connector is 0.6 dB and 0.1 dB of each fusion splicing point. Suppose we use 10GBASE-LR SFP+ module to build a network covering 2 connectors, 4 fusion splicing points. This module is interfaced with LC single mode fiber patch cord. If the single mode fiber cable has the wavelength of 1310 nm, the cable loss is about 0.35 dB per kilometer.

The worst optical loss = Power Budget – Total Optical Power Loss=6.2 dB – 1.2dB (2×0.6 dB) – 0.4dB (0.1×4) – 3dB (safety factor) = 1.6 dB
Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/km]=1.6dB/0.35dB/km
So we can get 10GBASE-LR SFP+ module can support at least 4.57 km at this occasion. Data transmission distance is mainly influenced by the optical power budget and fiber cable loss. From the above content, the optical power budget of 10GBASE-SR SFP+ is smaller than that of 10GBASE-LR SFP+ module. The more the optical power budget, the further the fiber transceiver can support. What’s more, the cable loss of multimode fiber cable is larger than that of single mode fiber cable. Obviously 10GBASE-LR SFP+ module can support longer link distance than 10GBASE-SR SFP+.

network building

Note: The optical power budget is based on a theoretical calculation, and is just for reference. The transmission distance should be calculated based on the power budget of fiber transceiver module tested on the switch and some practical attenuation.

Conclusion

Tx power and Rx power level of a transceiver are the main factors of transmission distance. The more the optical power budget, the better the transceiver. Before purchasing a transceiver, you’d better calculate the optical power budget according to transceiver module details.

Related Article:  10G SFP or 10GBASE-T SFP for 10GbE Network?

Why not Use Third-party Fiber Transceivers for Your Ubiquiti Switches?

Ubiquiti is famous for its switches such as Edge Switch, Edge Router, UniFi switch. Last year, this manufacturer officially released its own SFP and SFP+ fiber optic transceivers which are compatible with their switches. At the same time, it’s said that fiber transceivers from some fiber optic transceiver manufacturers such as Fiberstore can support Ubiquiti switches. This article will discuss what kind of third-party fiber transceivers are compatible with Ubiquiti switches and which fiber optic transceiver manufacturers is the most reliable.

Ubiquiti Fiber Transceivers

Ubiquiti switches are specially designed for 1G and 10G network. They didn’t produce their own fiber transceivers until last year. They only provide a small amount of single mode and multimode fiber transceivers. UF-MM-1G and UF-SM-1G-S are designed for SFP ports on Ubiquiti switches. And fiber transceivers like UF-MM-10G, UF-SM-10G, UF-SM-10G-S are for Ubiquiti switches’ SFP+ ports.

Third-party Fiber Transceivers For Ubiquiti Switches

Except their own SFP or SFP+ transceivers, those from other fiber optic transceiver manufacturers like Cisco, Dell, HP, Finisar, Brocade have been tested to be compatible with Ubiquiti switches by some users. Cisco, the world famous fiber optic transceiver manufacturer, has seven SFPs supporting Ubiquiti switches, Cisco GLC-LH-SM 30-1299-01 SFP, Cisco GLC-SX-MM, Cisco GLC-SX-MM 1000BASE-SX SFP, Cisco SFP-H10GB-CU1M, Cisco MGBSX1 Gigabit SX Mini-GBIC SFP Transceiver and Cisco GLC-T. Besides, for 10G network, Cisco SFP-10G-SR can be plugged in SFP+ ports on their switches.

Fiberstore Fiber Transceivers For Ubiquiti Switches

Fiberstore also has a wide variety of SFP and SFP+ transceivers compatible for Ubiquiti switches. Users have recommended some SFPs and SFP+s from Fiberstore, for instance, SFP1G-LX-31 1310nm (single mode SFPs), SFP-1G85-5M (multi-mode), SFP-GB-GE-T Module, SFP-10G85-3M (multi-mode).

Comparison Between Ubiquiti and Fiberstore Fiber Transceiver

There are so many third-party transceiver manufacturers providing compatible fiber transceivers fro Ubiquiti switches. But which fiber transceiver supplier should you choose? The answer is Fiberstore. Now let’s see why Fiberstore is more advantageous by comparing Ubiquiti with Fiberstore fiber transceiver.

    • Fiber Transceiver Category—Ubiquiti has only one single mode SFP and one multimode SFP. As to SFP+ transceivers, there only two single mode modules and one multimode module. The fiber transceiver category is very limited. While users have plenty of choices for SFPs and SFP+s from Fiberstore. As mentioned above, Ubiquiti switches support some fiber transceivers from third-party fiber optic transceiver manufacturers. Fiberstore offers many compatible brands like Cisco, Dell, HP, Finisar, Brocade, etc. Those SFPs and SFP+s have been tested to be suitable for Ubiquiti switches.
    • Fiber Transceiver Quality—Some fiber optic transceiver manufacturers produce SFP and SFP+ transceivers with low price. However, the quality of those fiber transceivers can’t be assured. In our test center, we have switches from Cisco, Dell, Extreme, Juniper and other famous brands. Every fiber transceiver offered by Fiberstore before shipping has to go through strict test to assure 100% compatibility and high performance.

fs fiber transceiver

    • Fiber Transceiver Price—Except fiber transceiver quality, fiber transceiver price is another important factor to be considered. Compare fiber transceiver price of Fiberstore with that of other fiber optic transceiver manufacturers, it’s obvious that Fiberstore has more advantages. That’s one of the reasons why Fiberstore wins popularity among customers. You can check the following screenshots about the feedback from customers.


customer review2

Conclusion

If you have to purchase fiber transceiver for your Ubiquiti switches, you can get SFP or SFP+ from Ubiquiti. Or you can buy from third-party fiber optic transceiver manufacturers. How to choose a reliable supplier from so many fiber transceiver manufacturers? When buying fiber transceiver, the quality, price, and after-sales service should be considered. As one of fiber optic transceiver manufacturers, Fiberstore is suggested to be a good choice for fiber transceiver needs. For more information about FS.COM fiber transceiver, please visit our site www.fs.com or contact us via sales@fs.com.

Related article of my blog: Transceiver Solutions for Ubiquiti UniFi Switches