Hello, everyone!
Today, I will continue to explain data center cabling. In this article about data center cabling, I will talk about copper cables – UTP, coax and AOC cables.
As I said in the last article, data centers use three kinds of cables: AC/DC power cables, ground cables, copper (UTP and/or coaxial) cables and optical cables (SM or MM fibers). I will only talk about telecommunication cables – copper and optical cables.
First, I want to explain copper cables. For data centers, we can use classic UTP cable, coax and AOC cables.
Coax and AOC (hybrid Active Optical Cables) cables can be used for very short links. Special coax cables – CX-4, CR4, CR10 are from 1 to 100 Gbps and for about 5 m. This type of cable requires an SFP module interface. We can see CX-4 in the next figure.
Figure 1. CX-4
AOC is a hybrid cable, it uses parallel optics with transceivers permanently attached to the cable. These transceivers are used for connection to SFP receptacles. This type of cable can be used for only short links, too. But we can use these cables from 10 to 100 Gbps. Figure 2. shows us this type of cable.
Figure 2. AOC
UTP cable can be used for a maximum of 90 (permanent link) + 10 m (patch cords). Some categories of UTP cables have shorter distances (for example Cat 8, maximum is 30 m). Except for distance, the big problem for copper cables is the speed limit. The new UTP cable – Cat 8 can be used for a max 40 Gbps, all other categories of this cable are for lower data rates.
In addition to problems with distance and data transfer speed, there is also the problem of power consumption of transceivers. Consumption with copper cables can be 10 times higher than consumption with optical cables. The consumption of copper transceivers maybe 5 - 6 W, while the fiber transceiver has a consumption of about 0.5 - 1 W.
Finally, I show a table of cables used in data centers.
I will continue to explain this theme in the next article >> Data center cabling (4): MM fibers.
Thank you!
