With a rapid development in the field of optical communications, the public tends to have higher requirements for the optical transceiver modules. Optical transceivers of 10G Ethernet cannot satisfy the increasing demands any more. At this time, the 40G transceiver, especially 40G QSFP transceiver, is emerged to meet the demands. The upcoming paragraphs will first introduce the concepts of QSFP and 40G Ethernet, then explain two kinds of 40G QSFP transceivers.
What is QSFP?
The QSFP (quad small form-factor pluggable) is a compact, hot-pluggable transceiver used for data communications applications. It interfaces networking hardware to a fiber optic cable and allows data rates from 4x10 Gbit/s. The QSFP specification accommodates Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards with different data rate options. QSFP+ transceivers are designed to carry Serial Attached SCSI, 40G Ethernet, QDR (40G) and FDR (56G) Infiniband, and other communications standards.
40G Ethernet Standards
40 Gigabit Ethernet is a group of computer networking technology for transmitting Ethernet frames at rates of 40 gigabits per second (40 Gbit/s). It was first defined by the IEEE 802.3ba-2010 standard. The 40 Gigabit Ethernet standards encompass a number of different Ethernet physical layer (PHY) specifications. The following nomenclature is used for the physical layers.
| Physical layer | 40 Gigabit Ethernet |
| Backplane | 40GBASE-KR4 |
| 7m over twinax copper cable | 40GBASE-CR4 |
| 30m over "Cat.8" twisted pair | 40GBASE-T |
| 100m over OM3 MMF |
40GBASE-SR4
|
| 125m over OM4 MMF | 40GBASE-SR4 |
| 2km over SMF, serial | 40GBASE-FR |
| 10km over SMF | 40GBASE-LR4 |
| 40km over SMF | 40GBASE-ER4 |
According to the 40 Gigabit Ethernet standards, 40G QSFP transceivers have various types, such as QSFP-40G-LR4, QSFP-40G-SR4, QSFP-40G-PLR4 and so on. The two most common types (QSFP-40G-LR4 and QSFP-40G-SR4) will be explained in the ensuing sections.
QSFP-40G-LR4
By the 40 Gigabit Ethernet standards, QSFP-40G-LR4 supports 40 gigabit data stream over 1310nm single mode fiber through an industry-standard LC optical connector. Its link lengths can reach up to 10km. QSFP-40G-LR4 converts 4-channel 10Gb/s electrical input data to 4 CWDM optical signals, and multiplexes them into a single channel for 40Gb/s optical transmission. Reversely, on the receiver side, the module optically de-multiplexes a 40Gb/s input into 4 CWDM channels signals, and converts them to 4 channel output electrical data. QSFP-40G-LR4 is commonly deployed between data-center or IXP (Internet Exchange Point) sites.
QSFP-40G-LR4 Transceiver Module
QSFP-40G-SR4
QSFP-40G-SR4 is a type transceiver for multimode fiber and uses 850nm lasers. It supports link lengths of 100 meters and 150 meters respectively on laser-optimized OM3 and OM4 multimode fibers. It primarily enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber connectors. And also it can be used in a 4x10G mode for interoperability with 10GBASE-SR interfaces. The 4x10G connectivity is achieved by using an external 12-fiber parallel to 2-fiber duplex breakout cable, which connects the 40GBASE-SR4 module to four 10GBASE-SR optical interfaces. QSFP-40G-SR4 is intended for use short reach applications in switches, routers and data center equipment where it provides higher density.
QSFP-40G-SR4 Transceiver Module
In all, 40G QSFP transceiver modules could provide a wide variety of high density 40 Gigabit Ethernet connectivity options for data center and high performance computing networks. It is a great solution for multi-lane data communication and interconnect applications. Fiberstore has various 40G QSFP transceivers, such as QSFP-40G-LR4, QSFP-40G-SR4, QSFP-40G-CSR4, QSFP-40G-PLR4, etc. If you are looking for a 40G QSFP transceiver, Fiberstore would be a primary option.
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