Brief Comparison between QSFP-40G-LR4 and QSFP-40G-PLR4

Recently data center has gone through great migration from 1G, 10G to 40G, 100G over the past few years. IEEE 802.3ba standard ratified the 40G Ethernet on June 17, 2010. Since then several types of 40G optical transceivers were developed to achieve 40G network, of which QSFP is the most commonly used type available on the market. There are many different variants of 40G QSFP, like QSFP-40G-LR4 (in following picture), QSFP-40G-PLR4. What is the difference between them? This passage will provide a satisfying answer for you.

Difference Between These two Modules The most obvious difference between QSFP-40G-LR4 and QSFP-40G-PLR4 is that QSFP-40G-PLR4 has a plus letter “P”. In fact, it means parallel. And In digital data transmission, data transmission usually occurs in two modes—serial and parallel. Parallel transmission is the simultaneous transmission of multiple bits over two or more separate paths, which allow for higher data transfer rates than can be achieved with serial transmission. While serial transmission is the sequential transmission of bits over a single wire frequency or optical path. It reduces the wire cost but slows the transmission speed at the same time. Thus QSFP-40G-LR4 uses the LC connector to achieve serial transmission. While QSFP-40G-PLR4 transceiver terminates with the MPO/MTP connectors to reach parallel transmission. Expect for different optical connectors, they are distinguished by the following features.

• Wavelength

QSFP-40G-LR4 (Multiplexing and demultiplexing of the four wavelengths are managed within the device): 1271 nm, 1291 nm, 1311 nm, 1331 nm QSFP-40G-PLR4: 4×1310nm

• Transmission Distance

QSFP-40G-LR4 and QSFP-40G-PLR4 both support link lengths of up to 10km.

• Interoperability

For QSFP-40G-LR4, the 40 Gigabit Ethernet signal is carried over four wavelengths. Multiplexing and demultiplexing of the four wavelengths are managed within the device, which interoperates with SFP+ CWDM.

For QSFP-40G-PLR4, it interoperates with 10GBASE-LR (10km) and 10G-LRL (1km) with 4×10G splitter option.

• Cable Type

40GBASE-LR4 supports up to 10km on 9um SM fiber (same fiber used for 10G single mode 10GBASE-LR). QSFP-40G-PLR4 can support 4 individual 10G-LR connections using a 4×10G mode and fiber breakout cables or cassettes for single mode fiber.

Additional Information There are another two 40G transceiver modules that are similar to each other, that is 40GbE PLRL4 and 40GbE PLR4. 40GbE PLRL4 (The parallel LR4 Lite) supports distances of 1km on single mode fiber which is compatible with 10GBASE-LRL standard. In addition, the PLRL4 optic can support 4 individual 10G-LR connections using a 4x10G mode and fiber breakout cables or cassettes for single mode fiber. While 40GbE PLR4 (parallel LR4) is compatible with 10GBASE-LR and 10GBASE-LRL supporting distance of 10km (or 1km) on single mode fiber. In addition the PLR4 optic can also support 4 individual 10G-LR connections using a 4x10G mode and fiber breakout cables or cassettes for single mode fiber.

Conclusion To sum up, QSFP-40G-LR4 and QSFP-40G-PLR4 are distinguished with each other in the above features as well as 40GbE PLRL4 and 40GbE PLR4. Fiberstore, a professional telecom manufacturer and supplier, offers a wide variety of high-density and low-power compatible 40G Ethernet optical transceivers including Avago QSFP+, Brocade QSFP+, Dell QSFP+ and HP QSFP+, etc. Fiberstore JG661A is compatible with HP QSFP-40G-LR4. They are very popular among users for its large stocks, competitive price and high quality. We can also customize optical products to meet your own requirements. If you are interested in our products, please send your inquiry to us.