What is a 40GB QSFP Optical Transceiver?

With the development and the rapid growth in data traffic in the recent years, the demands for high speed Internet connection and Data Transmission grew bigger and bigger. The new network technologies that are being developed are constantly pushing the existent equipment to the limit. The leading network manufacturers are constantly working on the latest technology solutions to assure high bandwidth, scalability, reliability and cost reduction. One of these new technologies and one of the latest developments in the networking world is the development of the 40GB Ethernet solutions together with the supporting components of the optical connection, transceivers and optical cables.

40GB Ethernet is becoming more and more popular for the leading Service Providers and Datacenters to use in their core networks. This is mainly because of the current cost of deploying a 100GB Ethernet solutions. In 2010 the IEEE standard 802.3ba standardized several 40GB Ethernet solutions and defined a number of fiber optic interfaces. These interfaces satisfy the support of Multi-mode and Single-mode fibers. Today 40GB Ethernet is the main machine that drives the core and aggregation layers, leaving the 10GB Ethernet to handle the Access Layer traffic. 40GB Ethernet solutions are mainly relying on the 40GB QSFP Optical Transceivers as their main engine.

An Optical Transceiver is an optical chip that uses optical connection to communicate with other devices. It is composed of both transmitter and receiver which can operate independently. Both of them operate with their own circuitry which enables them to handle transmission in both directions. These transceivers convert the electrical input gotten of the device into an optical light and, with the help of the optical cable, this optical light is sent to the other side of the connection so that the other end transceiver can take it and convert it into an electrical signal that the device can handle. The optical transceivers convert the electrical input into optical light with the help of the photoelectric conversion. At the far end of the connection the data is received as light impulses.

The QSFP stands for Quad Small Form-Factor Pluggable optical transceiver. This hot-pluggable optical transceiver is most commonly used in Datacenter environment to support the large bandwidth demanding applications. These transceivers are similar in size to the CXP transceivers. They provide 4 transmit and 4 receive channels. The maximum distance of these QSFP transceivers depends on the type of cables used. To put things in perspective, for distance up to 100 meters OM3 Multi- mode fibers would be used and for distances up to 500 meters OM4 Multi- mode fibers would be used. Like the SFP and SFP+, QSFP also supports copper cables such as Direct Attach Cables (DAC) which are terminated with special electricity coupled fitting that fit perfectly into the QSFP port. The basic and mostly used versions of QSFP are SR4 and LR4 and both of these can support Single-mode and Multi-mode fibers. SR and LR stand for short reach and long reach. The main difference between them, if we don’t take the obvious distance capabilities into consideration, is their connectors. The 40GBASE-SR optical transceiver uses MPO/MTP connector unlike the 40GBAS-LR which uses Duplex connector. However with the new IEEE 802.ba standard in place the use of parallel optics is a must because they provide a multiple lanes of traffic per channel.

When it comes to installing a QSFP type of transceiver there are some differences between QSFP Single-mode and QSFP Multi-mode transceivers to know:

These transceivers will for sure be used in the future and together with 100GB Ethernet solutions they will become the Internet backbone for the future generations, pointing in the right way to 200GB and even 400GB Ethernet development.