A combo port, also known as an optoelectronic multiplexing interface, is a photoelectric composite port with two kinds of Ethernet interfaces (RJ45 port and SFP port) on an Ethernet switch. An all-optical Ethernet switch is a network switch whose service ports are entirely optical, meaning every interface uses fiber rather than copper. Port types are limited to two: optical and Ethernet. In other words, it is a compound port that can support two different physical layers and share the same. It's a switch-port planning guide: how to map access / aggregation / core roles to the right port form factors (SFP+/SFP28/QSFP28/QSFP-DD), then choose DAC/AOC/fiber + connectors (LC vs MPO) without creating rework later. They can function as core, aggregation, and access devices on campus networks and connect to upstream and downstream devices.
[pdf] Whether it is simplex or duplex does not change the ferrule geometry, polishing quality, or optical coupling mechanism. Instead, it defines how many fibers are grouped together and how transmit and receive paths are. An LC connector is a 1. LC connectors are a ubiquitous fiber. LC stands for a type of optical connector of which the full name is Lucent Connector. It comes with the name because the LC connector was first developed by Lucent Technologies (Alcatel-Lucent for now) for telecommunication applications. It uses a retaining tab mechanism and the connector body. This guide provides a fully updated and industry-ready overview of LC fiber optics, explaining the origin and design of LC connectors, their key features, and the complete ecosystem of LC-based products used in modern networking.
[pdf] 
