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SFP-10G-SR vs SFP-10G-LRM vs SFP-10G-LR, Which to Choose?

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Posted on March 7, 2020
October 23, 2020
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SFP-10G-LRM module is a special SFP+ module since it supports both MMF and SMF transmission. There are other SFP+ modules that offer 10 Gigabit MMF and SMF transmission as well, such as the SFP-10G-LR and SFP-10G-SR. Then what's the difference between SFP-10G-LRM and SFP-10G-SR, SFP-10G-LRM and SFP-10G-LR? Read through this post to get more details on their differences and choosing guide.

The table below lists several main similarities and differences of SFP-10G-SR vs SFP-10G-LRM vs SFP-10G-LR:

Models Wavelength Fiber Mode Distance Connector Standard
SFP-10G-SR 850 nm Multimode 300 m Duplex LC 10GBASE-SR
SFP-10G-LR 1310 nm Single mode 10 km Duplex LC 10GBASE-LR
SFP-10G-LRM 1310 nm Multimode 220 m Duplex LC 10GBASE-LRM
SFP-10G-LRM 1310 nm Single mode 300 m Duplex LC 10GBASE-LRM
SFP-10G-LRM2 1310 nm Single mode 2 km Duplex LC 10GBASE-LRM

Note: The SFP-10G-LRM2 optical transceiver is an upgraded version of the SFP-10G-LRM optical transceiver.

From the chart above, the three types of 10G SFP+ module have much in common but differ in wavelength, fiber mode and transmission distance in general. Then, how should we choose among them? Is there big difference choosing one over another when two of them meet our demands at the same time? Here, we will focus on the comparision of SFP-10G-LRM vs SFP-10G-SR and SFP-10G-LRM vs SFP-10G-LR.

SFP-10G-LRM vs SFP-10G-SR

SFP-10G-SR transceivers and SFP-10G-LRM transceivers both support MMF transmission. The former supports 300m over OM3 cable and 400m over OM4 cable while the latter supports 200m over OM3 or OM4 cable. So, how to choose between the two? Normally, when the transmission distance is less than 300 meters, SFP-10G-SR is recommended. However, if you have other requirements, for example, 200m transmission with modal bandwidth of 500 MHz km, then SFP-10G-LRM transceiver is necessary. For more subtle difference, refer to the following chart:

10G SFP+ Wavelength (nm) Cable Type Core Size (Microns) Modal Bandwidth (MHz km) Cable Distance
SFP-10G-SR/ SFP-10G-SR-X 850 MMF 62.5 160 (FDDI) 26 m
62.5 200 (OM1) 33 m
50.0 400 66 m
50.0 500 (OM2) 82 m
50.0 2000 (OM3) 300 m
50.0 4700 (OM4) 400 m
SFP-10G-LRM 1310 MMF 62.5 500 220 m
50.0 400 100 m
50.0 500 220 m

Given that many users are still using OM1 and OM2, the persuit for SFP-10G-LRM transceiver is bigger than SFP-10G-SR transceiver because the transmission distance of SFP-10G-SR is only 33m over OM1/OM2, while SFP-10G-LRM can support 220m over OM1/OM2. Remember that to ensure compliance with specifications through FDDI, OM1, and OM2 fiber on SFP-10G-LRM, the transmitter should be coupled through a mode conditioning patch cable (MCP cable). For applications that over OM3 fiber or OM4 fiber, no mode conditioning patch cable is required. It is highly recommended to measure the power level before plugging the fiber into the adjacent receiver. When the received power is more than 0.5dBm, you should plug a 5-dB attenuator for 1300nm at the transmitter source of the optical module on each side of the link.

SFP-10G-LRM vs SFP-10G-LR

The SFP-10G-LR transceivers are designed for long-range communications up to 10 km, such as wiring buildings together on a large campus or even setting up a Metro Area Network (MAN). In addition to MMF transmission, SFP-10G-LRM could also support SMF transmission, in which there will be no saturation over SMF and the 10GBASE-LRM devices can reach up to 300 meters. For transmission within 300 meters, choose SFP-10G-LRM is an economical solution. For 300m-2km transmission, a SFP-10G-LRM2 optical transceiver is also a better choice than SFP-10G-LR since LRM2 has a relatively lower price given the same transmission range. For 2-10km transmission, the SFP-10G-LR is the only option.

Note: The SFP-10G-LRM2 optical transceiver has a maximum transmission distance of up to 2 km over SMF.

Summary

From all the above, it is not difficult to understand the difference of SFP-10G-SR vs SFP-10G-LRM vs SFP-10G-LR. Normally, SFP-10G-SR modules are more recommended than SFP-10G-LRM for short-reach 10G application within 300 meters. However, it depends. When users have special requirements that only LRM over MMF could support, SFP-10G-LRM is a necessity. And if the transmission is more than 300 m and less than 2 km, SFP-10G-LRM2 is a better choice. For the network that requires a link length of 2-10 km, SFP-10G-LR modules are better suited.

Related Articles:

10G SFP+ Types
10GBASE-T vs SFP+ vs DAC: How to Choose for 10GbE Data Center Cabling?