Harnesses are custom-engineered to allow seamless integration into various Storage Area Network (SAN) directors. Harnesses are used to transition the 12-fiber MPO connectors into LC connectors. A pinned MPO connector on one end connects to a trunk through a connector panel in the housing, while the other end is equipped with six LC-style uniboot connectors, which plug into optoelectronic ports.
As with jumpers, bend-insensitive fiber reduces the cable diameter and allows for the uniboot design described above. Additionally, the new fiber allows for an innovative new design of the harness furcation, resulting in the overall length reduction of the furcation. The bend-insensitive fiber also eliminates the need for bend radius control components at both the front and rear of the furcation such as segmented boots, heat shrink,spiral wraps and other such support. Likewise, this allows for precision staggering of the harness legs without using the above-mentioned radius control components. MPO connector leg slack can be stored in the vertical manager without fear of inducing macrobend attenuation loss. Figure 21 shows an engineered uniboot harness, Figure 22 shows the harness installed in the equipment rack, and Figure 23 shows the harness connected to a 48-port blade server.
The use of harnesses provides an innovative solution that occupies less space than traditional jumpers as the cable end of the harness is much smaller than the 12 equivalent patch cords. This reduced cabling bulk improves airflow for increased cooling and facilitates easier moves, adds and changes (MACs).
In typical data center applications, trunk cable branch into 12-fiber legs at a furcation plug that provides cable demarcation and strain relief. Each leg is equipped with an MPO connector, which is a 12-fiber push/pull optical connector with a footprint similar to the SC simplex connector. These high-density connectors are used to significantly accelerate the network installation process, minimize errors and reduce space. Trunks in data center applications utilizing MPO connectors typically support 12 to 144 fibers. Figure 24 shows a 144-fiber trunk cable assembly with a pulling grip on one end for ease of installation.
Through the use of bend-insensitive fibers in micro-module cable designs, trunk cables are on average 30 percent smaller in outer diameter. In addition, the minimum bend radius is now five timesthe outer diameter of the cable compared to 10 times the diameter in traditional trunks. Smaller-diameter trunks allow for more than 50 percent more cables to be stored in cable trays, while minimizing cable tray weight and impediments to cooling air.The smaller bend radius allows for extra cable slack to be stored without interfering with cable routing or causing attenuation that may adversely impact system performance.
Plug & Play Universal Systems utilize the MTP® Connector. The MTP Connector is a multi-fiber array-style connector that can accommodate up to 12 fibers in roughly
the same size and footprint as an SC connector. It has a single high-density footprint of 25 x 10 mm and features simple push-on/pull-off mating. A general industry term for this style of connector is MPO. This connector, which is used in both multimode and single-mode applications,maximizes valuable panel and hardware space, ensuring high density. MTP Connectors are manufactured with either alignment pins or with alignment holes to ensure proper alignment of the fibers. A connector with alignment pins always mates with a connector with alignment holes. (Figure 7.1). The MTP Connector offers:
• Up to 54 percent reduction in pathway congestion
• Modularity and scalability with a fiber count that maps to current and future line-card port counts
• Universal wiring and superior loss performance for migration to higher data rates
A traditional Plug & Play Universal Systems trunk consists of an optical cable with each end factory-terminated with MTP Connectors and a pulling grip on one or both ends.Trunks are available in a variety of fiber types and typically carry a plenum rating unless otherwise specified. When ordering Plug & Play Universal Systems trunks, the MTP Connectors on both ends will have pin alignment holes. This ensures that it will integrate with the remaining parts of the system that have pins. It should be noted that MTP Connector panels have neither pins nor alignment holes, as they are connection points for various components of the Plug & Play Universal Systems.
To successfully deploy a cable that is preterminated on both ends, it is necessary to accurately predetermine the installed link length. This can be relatively straightforward if welldefined pathways and spaces exist for the cable route, which is usually true for the data center environment. If the route is less defined, preterminated cables can still be utilized by specifying the trunk cables be longer than the known length and planning for the storage of excess cable loops.
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