A FC switched fabric uses the following port types:
N_Port: An end point in the fabric i.e. a Node port. Typically a host HBA port or storage array front-end port.
E_Port: A port that forms a connection between two FC switches i.e. an Expansion port. Link formed by two connected E_Ports is called an Inter-Switch Link(ISL).
F_Port: A port on a FC switch that connects to an N_Port i.e. a Fabric port that connects to an end point node.
G_Port: A generic port on a FC switch that act as either an E_Port or F_Port. It’s actual functionality is determined when the port is initialized.