What Is the Difference Between Singlemode QSFP+ and Multimode QSFP+?

The singlemode QSFP+ and multimode QSFP+ here mean the QSFP+ transceivers which work at different types of optical fibers, ie singlemode QSFP+ will work with singlemode fiber, while multimode QSFP+ will work with multimode fiber. So, what’s the different between them? And what should we notice when using them? Which one should I choose? In this article, we will have a discussion around this topic.

Singlemode QSFP+ vs. Multimode QSFP+
  • Singlemode QSFP+

Singlemode fiber (SMF) has much tighter tolerances for optics used. The core is smaller and the laser wavelength is narrower. This means that SMF has the capability for higher bandwidth and much longer distances in transmission. Singlemode QSFP+ (SMF QSFP+) works mainly in 1310nm wavelength and is mostly used in long distances transmission. There are many different types of Singlemode QSFP+, and different type can achieve different transmission distance, such as 500m, 1km, 2km, 10km and 40km. he color of compatible fiber optic patch cord is yellow. SMF QSFP+ usually uses duplex LC connector, but there also are some types use MPO/MTP connector.

  • Multimode QSFP+

Multimode fiber (MMF) uses a much bigger core and usually uses a longer wavelength of light. Because of this, the optics used in MMF have a higher capability to gather light from the laser. In practical terms, this means the optics are cheaper. The common multimode QSFP+ (MMF QSFP+) works in 850nm wavelength and is only used for short distance transmission reaching 100m and 500m. Though it’s not able to transport for long distance, it can transport many kind of optical signals. MMF fiber QSFP+ usually uses MPO/MTP connector, but some SMF&MMF QSFP+ can also use duplex LC connector.

Choose a Singlemode QSFP+ or Multimode QSFP+?

SMF QSFP+ and MMF QSFP+ may have different transmission distance and connectors, which is the most important factors you should consider when to make a decision. In the table below, I display the specifications of some main SMF QSFP+ and MMF QSFP+. Hope to help you to choose the right QSFP+ for your network.

Type Wavelength Fiber and Distance Connector Original model
40GBASE-SR4 QSFP+ 4x850nm 100m(OM3) 150m(OM4) Male MPO Cisco QSFP-40G-SR4
40GBASE-CSR4 QSFP+ 4x850nm 300m(OM3) 400m(OM4) Male MPO Cisco QSFP-40G-CSR4
40GBASE-LX4 QSFP+ 1270,1290,1310,1330 nm 100m(OM3) 150m(OM4) 2km(SMF) Duplex LC Juniper JNP-QSFP-40G-LX4
40GBASE Universal QSFP+ 1270,1290,1310,1330 nm 150m(OM3) 150m(OM4) 500m(SMF) Duplex LC Arista QSFP-40G-UNIV
40GBASE-PLRL4 QSFP+ 4x1310nm 1km(SMF) Male MPO Arista QSFP-40G-PLRL4
4x10GBASE-LR QSFP+ Lite 4x1310nm 2km(SMF) Male MPO Finisar FTL4P1QL1C
40GBASE-LR4 QSFP+ 1270,1290,1310,1330 nm 10km(SMF) Duplex LC Cisco QSFP-40G-LR4
40GBASE-LR4-Lite QSFP+ 1270,1290,1310,1330 nm 2km(SMF) Duplex LC Finisar FTL4C1QL1C
40GBASE-LRL4 QSFP+ 1270,1290,1310,1330 nm 1km(SMF) Duplex LC Arista QSFP-40G-LRL4
40GBASE-PLR4 QSFP+ 4x1310nm 10km(SMF) Male MPO Arista QSFP-40G-PLR4
40GBASE-ER4 QSFP+ 1270,1290,1310,1330 nm 40km(SMF) Duplex LC Cisco QSFP-40G-ER4

What Should We Notice When Using Singlemode QSFP+& Multimode QSFP+

  • Ensure that the QSFP+ in both ends of the fiber patch cord are of the same wavelength. A simple method is that the color of the modules must be consistent.
  • In general, to ensure the data accuracy, short-wave QSFP+ modules use with multimode fibers (ie. aqua OM3 or OM4 fiber patch cord), while long-wave QSFP+ modules use with single-mode fiber (ie. yellow fiber patch cord).
  • Do not over bend or winding fiber optic cables when using them. This will increase the attenuation of light in transit.
  • If you don’t use the QSFP+, you must use the dust plug to protect the optical bore.

When we choosing the QSFP+ module, we must confirm the transmission distance and wavelength we want to use in. This will help us to choose the right QSFP+ modules more efficiently. In addition, the costs for transceiver modules which keep adding up over time will be a budget pressure for many users. To save more, we can choose the compatible module without sacrificing any quality or reliability but only with a low cost. Fiberstore, an excellent supplier, supplies 100% compatible fiber optic transceiver modules of many brands, such as Cisco, HP, Juniper, Brocade, Finisar etc. with a incredible discount that may be a good choice for you.

Source: http://www.cables-solutions.com/what-is-the-difference-between-singlemode-qsfp-and-multimode-qsfp.html

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