Copper Cabling for 40G Data Center

A heated debate over whether fiber will take place of copper in the near future has caught people’s attention lately. Five to seven years ago, fiber was considerably more expensive than copper and, as such, was used sparingly. As fiber price has dropped dramatically and our bandwidth needs have grown, data centers have started to use more fibers all the way to their infrastructure. Under this circumstance, people wonder that copper cabling may soon be out of the stage of telecom industry. But the truth is that there is a still a place for copper cabling in the data center, even in 40G data center.

Deploying Copper Cabling in 40G Data Center
The biggest market for 40G Ethernet (40GbE) is in data center for interconnection links with servers and storage area networks. There are lots of 40GbE devices that can be used in 40G data centers. 40G direct attach copper cable (DAC), especially passive copper cables (PCC) is one of those devices that can support 40GbE networking. PCC is the preferred alternative for short-reaches in the data center and as such, that won’t necessarily change as speeds increase. Copper cable assemblies are significantly more affordable than fiber, and many twinaxial cables available on the market today can support 40G for reaches of seven meters or less.

40G QSFP+ Passive Copper Cable
QSFP+ (Quad Small Form-factor Pluggable Plus) copper cable assemblies were developed for high-density applications, offering a cost-effective, and low-power option for high speed data center interconnects up to 10 meters. 40GbE passive copper cables provide robust connections for leading edge 40G systems and have extremely low power consumption which improves data center power consumption and thermal efficiency which are ideal for 40G LAN, HPC and SAN applications. QSFP+ to QSFP+ passive copper cable and QSFP+ to 4SFP+ passive breakout copper cable are the two common types of QSFP+ cables that will be introduced in the following picture. Let’s take QSFP-H40G-CU1M as an example, it is compatible Cisco QSFP+ to QSFP+ passive copper cable that is suitable for very short distances of 1m and offer a very cost-effective way to establish a 40-gigabit link between QSFP ports of Cisco switches.

QSFP+ DAC

Copper Cabling in 40G Data Center—Pros and Cons
One important thing to note is why the feasibility of using twisted-pair-copper cabling (with RJ-45 connectors) to support 40G Ethernet is so critical to the overall market. RJ-45 connector is with no double one of the most common connector types used in data networks. As the market continues to grow from 1G to 10G, the backward compatibility of this technology will continue to be of extreme importance as work continues towards 40G. This will allow data center operators to evolve their networks based on changing requirements and do so with the least amount of disruption and cost to their networks. In addition, twisted-pair-copper cabling has proven to be an extremely cost-effective solution and designers, installers, and customers have a lot of experience and confidence in copper-based networks. While the eventual deployment of 40G-based copper solutions is still a few years out, this technology will allow organizations to think about how they are deploying copper based solutions today with an eye to the future. Doing so correctly will help ensure infrastructure costs are well managed from both a product and support standpoint.

The problem of standard twinaxial cables is not their performance as much as their tendency to be stiff and bulky, thus consuming precious rack space and blocking critical airflow. The current copper solution for 40G Ethernet limits the architectures one can deploy. 40G Ethernet QSFP+ DAC cable assemblies have a reach of 5 to 7 meters. Thus QSFP+ DAC cable (or QSFP+ breakout cable) assemblies cannot be used for most end-of-row (EoR) implementations or other architectures. What’s worse, DAC cable assemblies are a point-to-point solution and therefore cannot support a structured cabling design. Designers must be careful not to bend the cables too much because the cable’s shielding and overwrap materials can distort the precise cable geometry needed to maintain impedance control, which can degrade signal performance. Moreover, the wrapped shield, with repeated breaks in the shield along the cable length, can produce an unwanted resonance effect, evident at certain frequencies.

Summary
Will copper be completely replaced by fiber in the near future? The answer is yes or no, we have no clue. But one thing is for sure that copper cabling continues to strive to achieve the quality and speeds that fiber can handily provides, while fiber will develop itself to be more competitive among designers. It is the good news for subscribers. Fiberstore is committed to provide first-class services and high quality products for users. If you have any question about today’s topic, please leave your messages to us.

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