Fiber optic cable types and their impact on the data center

Fiber optic cable types

Network administrators should be aware of bandwidth, compatibility, and management features when selecting fiber optic cables.

The fiber optic cable connection was originally limited to specific applications. Fiber optic cables have quickly become the standard for high-speed connections you can find at Sopto, partly because of a consolidation of computing power. Therefore, network platforms are necessary that can combine several fast lines.

Other materials such as copper are still used in out-of-band networks, but are mostly used for lower bandwidth connections. Knowledge of the different types of fiber optic cable is now required to build modern data center networks.

SFP affects speed and compatibility

Many data center appliances require interfaces at speeds of up to 10 Gbps. While switching to 10 Gbps has encouraged copper-to-fiber migration, most network administrators in data centers only have experience with lower- bandwidth fiber optics. To cabling a longer link than the maximum 100 meters of copper, many companies use fiber optic cables with an SX-based transceiver or SX optics. SX optics support distances up to about 215 meters and are mostly available in Small Form-Factor Pluggable (SFP) modules.

The SFP format has become a standard for Ethernet connections at 1 Gbps; however, an SFP module can only provide a maximum bandwidth of up to 1.25 Gbit / s. To overcome this limitation, SFP + modules with the same form factor as the original SFP module provide up to 10 Gbps of bandwidth. In many cases, SFP + switches also support lower speed SFP modules; making 10 Gbps switches backwards compatible with 1 Gbps SFP modules.

As the majority of switch platforms today rely on SFP +, the switches are typically compatible with a variety of SFP and SFP + form factors. At speeds of 10 Gbps, SR optics are generally used for all applications that require this bandwidth. Reaching distances of over 300 meters with standard multimode fiber, this type of optics is ideal for most 10 Gbps data center applications.

While the SFP form factor is common today, the module on the switch and the type of optics are independent. As long as the optics match, the form factor of the module does not matter; it is possible to connect modules with 10 Gbit / s and different form factors. When connecting different modules together, companies should be careful to use the right fiber optic cable types because different form factors require different fiber connectors. Older modules rely on SC connectors, while the newer modules such as SFP and SFP require + LC connectors.

Fiber optic cables continue to evolve

To help administrators solve connection problems, the latest optical platforms include Digital Diagnostic Monitoring (DDM) or Digital Optical Monitoring. It provides information about the fiber optics of the corresponding platform. Although the majority of switches provide information to the administrator, DDM goes beyond that and provides important data in real time, such as the amount of light received or light wave energy, the transmission power, and the temperature of the transceiver.

Ideally, optical fibers conduct light without loss; but as a rule there is an attenuation of the light wave energy during transmission – it is measured in decibels and specified by the manufacturer. Using DDM information, admins can resolve optical connectivity issues and ensure that the transceiver and fiber optic cable work as expected. Because lower-cost optics typically does not include DDM functionality, companies should scrutinize transceiver characteristics before purchasing.

As fiber optic cables continue to gain in importance in the future, the share of copper lines in the data center will decrease. And with the higher demands on bandwidth, the need for innovation in fiber optic cables is also increasing. Companies can save time and money by constantly tracking development and knowing their options.

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