Fanout Technology in 40G Data Center
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Fanout Technology in 40G Data Center

Posted on by FS.COM

Driven by need for high speed Ethernet and increasing services like Cloud and virtual data center, migration from 10G to 40G is unstoppable. Except adding more devices and cables to get higher bandwidth and throughput, higher port density is also the widely accepted solution for data center migrating to 40G. To overcome the challenge of both data rate and cabling, fanout technology is being wisely applied in 40G data center in large scale. The principle of fanout is really simple. It’s kind of like the water pipeline in our building: water is transferred from the trunk pipeline in a building. Then trunk pipeline fans out into several pipelines that have smaller diameters to bring the water to every house.

It’s common that a device needs to be connected to two or several devices with different physical interface. Thus, the superiority of fanout technology is brought into full play, especially in the distribution layer of 40G data center and adapting lower data rate to 40G in cabling. This post will introduce several fanout/breakout assemblies that are widely used in 40G data center.

40G MPO Fanout Cables

The first introduced fanout assembly for 40G data center is MPO fanout cable. A MPO fanout cable is a multi-fiber optical cable that contains several individual tight buffered optical fibers with one end terminated with a male/female MPO connector and the other end usually terminated with several LC connectors.

MPO to 8 LC fanout cable

There are a variety of MPO fanout cables. For 40G cabling, what most customers need is breakout cable which is able to fan out into 12 fibers or 24 fibers. The above picture shows a typical 12-fiber MPO breakout cable (also called MPO harness cable) with OM3 optical fiber as the transmission media. This 12-fiber MPO fanout cable is terminated with 6 duplex LC connectors on one end and a male MPO connector on the other end, which can work from MPO trunk backbone assemblies to LC fiber rack system in high density backbone cabling from 40G device to 10G devices.

There is also a little bit smaller MPO fanout cable, of which the fibers fan out directly from the MPO connectors. This mini MPO harness cable can be easily put into patch panel and increase the cabling density effectively.

12-fiber MPO cassette

Another special type of MPO fanout cable is MPO cassette designed for those who want to have everything in neat and tidy. It breaks the traditional design of the fanout cable. By housing one or several mini size MPO fanout cables in a cassette, MPO cassette can offer better cable protection and management. For a 12-fiber MPO cassette, there will be a 12-fiber mini direct fanout MPO cable inside the cassette. With one MPO in the back side of the cassette and six duplex LC connectors in the front (shown in the above picture). This type of cassette can be installed in the standard rack in data center. To achieve higher cable density, more 12-fiber or 24-fiber mini MPO fanout cables are installed for 40G transmission. For example, the following is a picture of a 24-fiber MPO cassette containing two 12-fiber fanout cables, thus there are two 12-fiber MPO connectors on the cassette. A 24-fiber MPO cassette can also have a mini size 24-fiber fanout cable in side the cassette. This cassette will only have one 24-fiber MPO connector in the back side. No matter what the fiber count and connector type are, these MPO cassettes can be customized in Fiberstore according to your requirements.

24-fiber MPO cassette

40G Fanout Direct Attach Cables

Direct attach cable offering direct interconnection for devices in data center also has fanout design. Converting one form factor to a different form factor is necessary in many cases. For example, a 40G device may be connected to one or several 10G devices for distribution or adapting. With fanout DAC this process would be much easier. This pre-terminated components can also increase the reliability of data center effectively.

A 40G DAC usually has a 40G QSFP+ connector on one end, no matter it uses copper or fiber as the transmission media. On the other end of 40G DAC can be terminated with four 10G XFP connectors or four 10G SFP+ connectors.


Sometimes it also needs to convert QSFP+ to LC interface. There is also another type of 40G DAC can satisfy this requirement. This kind of DAC is attached with a QSFP+ on one end and several  LC connectors on the other end. For example, the above picture shows an active optical cable (AOC) with one end plugged into a QSFP+ switch and the other end attached with four duplex LC connectors which are separately linked to four 10G SFP+ transceivers. These 10G transceivers are then plugged into 10G switch with SFP+ ports. In this way, 40G cabling to 10G cabling is achieved.

Fanout technology is playing an important role in 40G data center. Products like 40G break out cable, cassette and 40G break out direct attached cable can all be customized in Fiberstore. Different connectors, cable length, fiber count etc. can all be specially designed according to your application. Please contact for more details about fanout products in 40G data center.

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