What Cabling Infrastructure Can Support 40G Data Center?

Posted on by FS.COM

Fiber connectivity in higher-speed active equipment tends to develop as more condensed and simplified with plug-and-play, hot-swap transceiver miniaturization. 1G and 10G networks commonly use SFP or SFP+(Small-form-factor pluggable plus). Interfaces of 40G is QSFP (Quad Small Form-factor Pluggable). The interface changes need different connectors to achieve network connectivity. So what cabling infrastructure requirements are needed to support 40G applications?

MPO/MTP Fiber Patch Cable

The IEEE 802.3ba standard specifies multi-fiber push-on (MPO) connectors for standard-length multimode fiber connectivity. MPO/MTP is the designated interface for multimode 40G. Its small, high-density form factor is ideal with higher-speed Ethernet equipment.

A 12-fiber MPO connector interface can accommodate 40G. Usually 40G data center uses 12-fiber MPO/MTP connectors. The typical implementations of MPO plug-and-play systems split a 12-fiber trunk into six channels that run up to 10 Gigabit Ethernet (depending on the length of the cable). 40G system uses 12-fiber trunk to create a Tx/Rx link, dedicating 4 fibers for 10G each of upstream transmit, and 4 fibers for 10G each of downstream receive. The upgrade path for this type of system entails simply replacing the cassette with an MPO-to-MPO adapter module.

MPO-parallel

Direct Attach Cable

Except MPO/MTP trunk or patch cord assemblies interconnecting QSFP+ transceivers, many data centers also likely to use 40G DACs (direct attach cable). DAC is a form of high speed cable with “transceivers” on either end used to connect switches to routers or servers. It a kind of optical transceiver assembly. DAC cables are not real optics and their components are without optical lasers. DACs are much cheaper than the regular optics. Just because the low cost and high performance, DACs are preferable for 40G data center applications and high-performance computing environments. Cost of connectivity is significantly reduced by avoiding the more costly fiber transceivers and optical cables. 40G DACs can provide inexpensive and reliable 40G speed connections using either active optical cables or copper cables.

  • Active Optical Cable

An active optical cable (AOC) consists of a bend-insensitive multimode or single-mode fiber cable terminated with a connector and embedded with transceivers that convert electrical signal to optical signal and back. AOC can reach a longer distance copper cables. AOCs use the same interfaces as copper cables and are typically used in data centers.

In data centers, people worry that power consumption and heat generation will increase with the high data rates. Last few years, cable assembly manufacturers have responded by releasing increasingly efficient AOC interconnects. For example, 3M makes a QSFP+ AOC assembly that uses approximately 475mW per end. In addition to lowering power consumption directly, low-power AOCs release less heat than higher-powered products, further driving down power consumption by reducing the need for cooling.

What’s more, AOC is reliable. Nowadays, consumers are less tolerant of errors and failure, so the reliability of all equipment becomes more critical. The tiny electronics embedded in the transceiver, which enable the electrical-optical-electrical conversion, carry a potential for failure. So cable installers are wise to choose AOC with test results confirming its reliability.

The following are Fiberstore AOCs with features like high performance, low power consumption integrated cable for short-range multi-lane data communication and interconnect applications.

40G AOC Type Image Data Rate  Cable Type  Connector Type 
QSFP+ to QSFP+ QSFP-to-QSFP Up to 40G Fiber QSFP+ AOC
QSFP+ to 4 SFP+ QSFP-to-4 SFP+ Up to 40G Fiber QSFP+ AOC
QSFP+ to 8X QSFP-to-8X Up to 40G Fiber QSFP+ AOC
  • Copper Cable

Even though 40G AOC has so many advantages, it doesn’t mean it can replace copper cable. Because copper cable has its own benefits. It is specially designed for short-reaches in data center. Copper cable assemblies are less expensive than fiber cable. Today there are many twinaxial cables available to support 40G (10G x four channels), per 40GBASE-CR4 specification. The following Fiberstore’s cost-effective copper cables provides much needed space for data centers.

40G Copper Cable Type Image Data Rate  Cable Type  Connector Type 
QSFP+ to QSFP+ QSFP-to-QSFP Up to 40G Copper Cable QSFP+ Passive Copper
QSFP+ to 4 SFP+ QSFP+ to 4 SFP+ Up to 40G Copper Cable QSFP+ to 4 SFP+
QSFP+ to 4 XFP QSFP+-to-4 XFP Up to 40G Copper Cable QSFP+ to XFP(4)

The problem is that copper cable is stiff and bulky, thus consuming precious rack space and blocking critical airflow. But with the advancing technology, manufactures produce a thinner, uniquely shielded ribbon-style twinaxial cable that can support speeds of 10G per channel while addressing many of the concerns associated with round, bundled cable. And the ribbon-style twinaxial cable is significantly slimmer than its round counterparts. Even better, the cable can be folded multiple times and still maintain signal integrity, allowing for higher density racks and space savings.

Conclusion

As the need of high data transport rates, the data center network migrates from 10G to 40 Gigabit Ethernet which provides a framework for data rates of 40 Gigabit per second. To support 40 Gpbs connectivity, there is a need to upgrade the cabling infrastructure. All our MPO/MTP fiber cables and 40G QSFP+ cables are low-cost and high-performing. Fiberstore can provide you a suitable way to achieve your 40G data rates in the most cost-effective manner.

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