The three most common MPO connector options are MPO-8, MPO-12 and MPO-24.

• MPO-8 is a legacy standard for the QSFPs, coming out of the transceivers running 40 Gigabit or 100 Gigabits. It is used for both multimode and singlemode transceivers and breakouts, but offers the lowest density option, because you’ll have to have more components for the MPO-8 as you move forward into higher speeds.
• The MPO-12 is the legacy embedded base and with the use of different modules and array fanouts can accommodate multiple configurations.
• MPO-24 is the newest option and is used on the trunk cables and modules. MPO-24 helps to future proof your network because it provides the highest panel density, allows you to use fewer components and may offer the lowest first installed cost. MPO 24 trunk implementations provide significant advantages for duplex and parallel implementations, providing for faster installation and better pathway efficiency.

In a leaf-spine architecture, a series of leaf switches form the access layer.These switches are fully meshed to a series of spine switches. Leaf-spine architectures are popular because they reduce the number of “hops” from server to server, which minimizes latency. One of the consequences of this approach is that it requires more physical connections to support that any-to-any connectivity. The physical layer becomes more important, because it needs to accommodate a simplex, duplex or parallel networking scheme. This means that sometimes the design, implementation, testing and validation can get fairly complex.

An unpinned MPO is inspected in the same way as a pinned MPO, however from an inspection perspective there’s no contact made with the fiber. You’d use the same inspection probes that will find the fibers, inspect them, and do a pass fail analysis. For cleaning, you can use the cassette style cleaners. In fact in some ways they are easier to clean than a pinned connector

Some important changes to TIA-942-B Data Center Standard include:

• Added MPO-16, MPO-32 (ANSI/TIA-604-18) and MPO-24 (ANSI/TIA-604-5)
• Added Category 8
• Changed recommendation to category 6A or higher
• Added wideband laser-optimized 50/125 µm multimode (OM5)
• Added 75-ohm broadband coaxial cables and connectors (ANSI/TIA-568.C-4)
• Added recommendations for fiber in non-continuous pathways that could cause micro bends
• Recommends that cabinets be at 1200 mm (48”) deep and to consider cabinets wider than 600 mm (24”) wide
• Recommends considering pre-terminated cabling to reduce installation time and improve consistency and quality of terminations
• Recommends considering need for proper labeling, cable routing, cable management, and ability to insert and remove cords without disrupting existing or adjacent connections
• Maximum cable lengths for direct attach cabling in EDAs reduced from 10 m (33 ft.) to 7 m (23 ft.). (Direct attach cabling between rows is not recommended).

Other relevant changes include:

• Change in return loss for single-mode fiber from minimum 26dB to minimum of 35dB, making field terminations more difficult
• Polarity in Testing; used to be covered in ANSI/TIA -568.0-D and now is addressed in 568.3-D.

In fiber optic systems for data centers, LC, SC and MPO optical fiber connectors are often used.

• SC (square connector) connectors have a push-pull coupling end face with a spring-loaded ceramic ferrule, and is ideal in data center applications.
• LC (Lucent connector) connectors – also push-pull connectors – came along after SC connectors, and feature a smaller ferrule (for this reason, it’s known as a “small form-factor connector”). Its smaller size makes it ideal for dense data center racks and panels.
• MPO connectors are used for ribbon cables with anywhere from eight to 24 fibers.

To support the high bandwidths required in data centers, most companies are installing at least OM4, laser optimized multimode fiber. Some companies are installing single-mode fiber, but that requires more expensive optics. A new option that is emerging is OM5, a wide bandwidth multimode fiber which allows short wavelength division multiplexing. This means the fiber can carry multiple wavelengths of light over the same fiber, increasing bandwidth significantly and yet still allowing the use of lower cost multimode optics.

WBMMF is a relatively new fiber medium specified in ANSI/TIA-492AAAE and given the designation of OM5 multimode fiber by ISO/IEC and TIA. This 50/125 µm multimode laser optimized fiber was originally developed to support Short Wavelength Division Multiplexing (SWDM) and supports 4 wavelengths of 25Gb/s transmission for an aggregated 100 Gb/s transmission on a duplex LC link, a popular and familiar interface in the data center. WBMMF supports four wavelengths between 850 nm and 953 nm, using multimode optics. WBMMF was designed for use in data centers.