Solutions for 40G Network Interconnection

With the migration of 40G Ethernet, it seems that Direct Attach Cable(DAC) is applied widely in the data center due to its high data rate and effective interconnection in the short time. Generally speaking, DAC consists of three types: passive copper cable, active copper cable and active optical cable. However, which one is the best solution for 40G network interconnection among of them? Well, different requirements, different solutions. This article will detailedly introduce it for us one by one from the perspectives of transmission distance, cost, power consumption, cooling function.

active copper cable

In most cases, the transmission distance, as the important part of DAC, is considered first at the process of selection about it. While in their comparisons from the view of transmission distance, there is no doubt that Active Optical Cable is dominant over the others. It’s known that passive copper cable is used for short distance, supporting 40G transmission up to 10m, while active copper cable, with optical module on the QSFP+ connector, and active optical cable, with optical transceiver on the connector,  is used for relatively longer transmission distance, respectively available for 40G transmission within 15 meters and up to 100 meters. 

Meanwhile, on the viewpoint of power consumption, it’s apparent that passive copper cable has advantage over them. On account that both of active copper cable and active optical cable have an active component to transmit/receive signal, it needs power to make its internal circuits work properly, in which the power consumption of active copper cable and active optical cable respectively is  440mW and over 2 W. While passive copper cable requires no power for internal electronics, which avoids consuming power or producing heat. Therefore, in such kind of situation, to some degree, the passive copper cable is the best choice among them for the data center. 

In addition, seen from their cooling effect, it seems that there is no way to tell apart. Apart from the power consumption, the cable size can also affect the cooling effect in the data center. Usually, the thinner the cable is, the better dispersion devices in data center will have. Among the three types of DACs, active optical cable is the thinnest, and active copper cable is thinner than passive cooper cable. But in spite of this, it doesn’t mean that active optical cable is the final choice. As mentioned above, AOC has the highest power consumption and active copper cable has lower power consumption, while passive copper cable requires no power. In the situation, it’s hard to make a decision.

Finally, with respect to the cost, it is clear that copper cable is much cheaper than optical cable. AOC, with optical transceiver on the connector is the most expensive one. If cost is not a problem, AOC will be strongly recommended, due to its best transmission performance. However, for many data centers, it’s hard to have an ideal situation like this. Most of the components in data center are expensive and require careful maintenance. Although passive copper cable is much cheaper than AOC, and in most cases, it cannot support 40G transmission in data center. While active copper cable is less expensive than AOC and can support longer transmission than passive copper cable. Therefore, comparatively speaking, active copper cables seems to be a good choice. 

All in all, for the application of passive copper cable, active optical cable and active copper cable in the 40G Ethernet, it depends on the practical and specific situations in the data center. As a result, if wanting to choose the best solution for it, it would be better to have a selection according to your practical requirements. After all, the most suitable is the best. Besides, Infiberone can also offer other professional suggestions for you freely. If you have any need, welcome to contact us any time.

Note: Infiberone is a sub-brand of Gigalight, we focus on high-end optical network devices, mainly supplying industrial-grade optical transceivers and professional optical interconnection components for data centers. With more than 10 years' experience in optics industry, we now have professional R&D team(more than 100 engineers) and stable supply ability.