Hub

A hub is a network component that centralizes circuit connections. Hubs started out as wiring concentrators but have developed into sophisticated switching centers.

MDI/MDIX is a type of Ethernet port connection using twisted pair cabling. The MDI (for medium dependent interface) is the component of the media attachment unit (MAU) that provides the physical and electrical connection to the cabling medium. An MDIX (for MDI crossover) is a version of MDI that enables connection between like devices. MDI ports connect to MDIX ports via straight-through twisted pair cabling; both MDI-to-MDI and MDIX-to-MDIX connections use crossover twisted pair cabling.