QSFP-40GE-LR4 and QSFP-40G-SR4 Modules Comparison
Have you ever complained about your slow network speed when you are working in a hurry, watching the most wonderful and interesting part of a movie or doing something else that are delayed by your bad network? Do you want to upgrade your system for higher data transmission speed? Have you ever heard about 40G QSFP+ module which is able to solve your problem? In this post, it will introduce two commonly used types of QSFP+ modules used to upgrade your network from 10G Ethernet to 40G Ethernet, to some extent, avoiding time delay.
40G QSFP+ Modules Overview
Nowadays, there are several solutions designed for deploying 40G Ethernet network, such as, 4 x 10GE Breakout cable, 40G QSFP+ modules or 40G CFP modules. Both of these solutions can achieve the 40GbE with higher capacity. As one of the most commonly used solutions among them, 40G QSFP+ module is a good choice to make the 40G migration. Do you have a good knowledge of 40G QSFP+ modules in the fiber market? At present, there are many variants of 40G QSFP+ modules published to support different applications, defined by IEEE 802.3ba. For instance, QSFP-40GE-LR4, QSFP-40G-PLR4, QSFP-40G-SR4, QSFP-40G-CSR4, etc.
Differences Between QSFP-40GE-LR4 and QSFP-40G-SR4
Among the variants of 40G QSFP+ modules, QSFP-40GE-LR4 and QSFP-40G-SR4 are the most widely applied modules that are designed for different aims. Their features are much different from each other, varying from fiber type to transmission distance. The following will basically analyze the differences between these two modules that may be useful for you to select a proper 40G QSFP+ module.
- Different Fiber Type
As for QSFP-40GE-LR4 module, it has four WDM lanes to transmit and receive signal, which generally works with single-mode fiber. With the advantage of single-mode fiber, it can transmit 40G signals with a long distance. As for QSFP-40G-SR4 module, it has four lanes, which enables high-bandwidth 40G optical links over 12-fiber multimode fiber, operating on a parallel mode. Although it can’t support long distance transmission like QSFP-40GE-LR4 module, it has the ability to carry many kinds of optical signals in 40G Ethernet network.
- Different Connector
As for the connector, QSFP-40GE-LR4 module always uses duplex LC connectors to connect single-mode fiber, while QSFP-40G-SR4 module is often terminated with MPO/MTP connector used for linking 12-fiber multimode fiber. What should pay attention to is that each kind of connector is easy to be smudged, which may cause a negative effect on the transceiver performance. Hence, no matter which module you choose to deploy 40G Ethernet network, please use a dust plug to protect the connector if the QSFP+ module is not working, so that the connector can be stay in a clean condition.
- Different Wavelengths
There is no doubt that the light wavelengths are also different used for transmitting signals. As for the former one, it generally uses signals with four different wavelengths, 1271 nm, 1291 nm, 1311 nm and 1331 nm to achieve 40G long distance data transmission. However, the latter one uses the same wavelengths for four lanes: 4 x 850 nm, supporting 40G short data transmission.
- Different Transmission Distance
It is easy to learn that the letter “L” in QSFP-40GE-LR4 refers to the word “long”, while the letter “S” in QSFP-40G-SR4 stands for “short”. Then how far these two QSFP+ modules can transmit 40G signals? What’s the difference? As for the former one, by using Coarse Wavelength Division Multiplexing technology, it transmit 40G signals through single-mode fiber with four separated or combined 10G SFP+ modules on the other end, with great reach of up to 10 kilometers. However, the latter one can only transmit 40G signals at lengths up to 100 meters on OM3. If it uses OM4 to support the 40G Ethernet network, it can transmit longer, 150 meters.
Conclusion
Have you got any useful information from the post for choosing a suitable QSFP+ module? As above mentioned, QSFP-40GE-LR4 designed with special features is most suitable for 40G long distance transmission, such as, between data-center or IXP sites. If you just need to deploy 40G Ethernet network for short distance, QSFP-40G-SR4 must be an ideal choice with lower price.
