The connection should be between adapter plate rows with the connector key sharing the same orientation. Because fiber duplex links rely on matched transmit-receive alignment, polarity determines how cables, connectors. Polarity in fiber optic networks refers to the alignment of transmit (Tx) and receive (Rx) signals between interconnected devices. For this signal alignment to work. Key orientation: MTP®/MPO connectors have an extrusion, called a "key", commonly described as key up or key down, that determines the insertion orientation into the adapter. This orientation directly affects the actual positional relationship of the fibers after mating. If the fibers are not crossed in the permanent cable plant, one duplex patch cord in the link needs to be crossed or simplex patch cords can be used and the proper connections made manually.
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