The FC interface is square

It is a large square connector with a rectangular sleeve on the outside. Fibre Channel (FC) is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data. It is used primarily for storage area networks (SANs). This document focuses on the Electrical Physical Layer up to 4G speeds. This type of connector is convenient for plugging and unplugging operations, has a small fluctuation in insertion loss, a relatively high compressive strength. LC (Lucent Connector) interface: The LC interface is a small optical fiber connector that is commonly used for high-density optical fiber connections, such as equipment connections in data centers and enterprise networks. [pdf]