Choosing Between a Base-8 or a Base-12 Cabling System

Base-8 and Base-12 fiber optic cabling systems differ primarily in their design, scalability, and efficiency for specific networking applications. A Base-8 system uses fiber groupings of eight, aligning well with modern transceiver configurations such as 40G, 100G, and 400G Ethernet, which often operate in multiples of eight fibers. This results in minimal unused fibers, maximizing port utilization and reducing overall cabling waste. Conversely, a Base-12 system groups fibers in sets of 12, a legacy standard that supports older network designs and is often more economical due to its established infrastructure. However, Base-12 systems can lead to inefficiencies in modern high-speed networks, as unused fibers (typically four in an eight-fiber configuration) increase complexity and costs in dense environments. The choice between Base-8 and Base-12 depends on factors like existing infrastructure, future scalability, and the specific requirements of the network’s bandwidth and connectivity.

 

MPO Connector Design

The three most prevalent MPO connector types include the MPO-8, MPO-12, and MPO-16. While an MPO-12 connector can be used in 8-fiber applications, four of its center fibers remain unused and do not transmit or receive light signals. Additionally, the MPO-16 supports 16-fiber applications and features an offset key to prevent incorrect connections with center-keyed optics or adapters such as the MPO-8 or MPO-12. As more connections are required, MPO-24 and MPO-36 connectors were introduced to increase fiber count within the same footprint.

 

Network Connectivity with MPO Connectors

Basic structured cabling with MPO connectors is the use of MPO trunk cables that are terminated with modules or patch panels on both ends. Where duplex optics need to be supported, an MPO-to-LC module can be deployed to present the fibers as LC duplex ports that can be connected with LC jumpers to the transceivers. The image below shows the network connectivity using a Base-8 trunk cable with a Base-12 trunk cable. Both configurations utilize 24 fibers, but the Base-8 solution includes an extra MPO connector, allowing for a future connection to parallel optics.

Without changing the trunk cable, the difference between the Base-8 and Base-12 system becomes apparent when the network is upgraded to use parallel optics. The Base-8 channel features three MPO connectors, enabling support for up to three parallel optics. In contrast, the Base-12 channel can only support two separate parallel optics. The Base-8 system offers one more discreet MPO connector to be plugged into a parallel optic using the same trunk cable.

The Base-8 system also provides an advantage when breaking out one parallel optic into multiple duplex optics such as a 100GBASE-SR4 to four 25GBASE-SR optics. The Base-12 system is also able to perform the same breakout architecture, but four fibers will remain unused.

 

The emergence of 400 Gb/s and higher-speed applications has resulted in solutions like 400GBASE-SR8, which employ 16 fibers through an MPO-16 interface. To incorporate MPO-16 optics into Base-8 cabling systems, Y cords (2xMPO-8 to 1xMPO-16 conversion cords) are used on both ends. The MPO-16 connector attaches to a 400GBASE-SR8 optic, dividing into two MPO-8 connectors that connect with the Base-8 MPO trunk. Conversely, the trunk’s two MPO-8 connectors combine into an MPO-16 connector to fit the other MPO-16 optic.

Similarly, the upgrade to a Base-16 MPO trunk cable can increase network density while still supporting existing Base-8 parallel optics. This upgrade also prepares the network for future expansion.

 

 

Conclusión

A Base-12 system might be sufficient for low bandwidth duplex optics. However, as the demand for bandwidth increases, the adoption of parallel optics will be inevitable. As Base-8 system utilizes all available fibers in the MPO connector, is backward compatible with duplex optics with the use of MPO to LC breakout modules, and can support future parallel optics using MPO-16, it is an optimal solution to ensure the network is well prepared for present and future applications.