Definition - What does Generic Port (G_Port) mean?
A generic port (G_Port) is a port that supports either an E_Port or F_Port in a fiber channel (FC) switch topology. It can be found on Brocade and McData switches.
The fiber channel was developed in 1988 and approved by the American National Standards Institute (ANSI) in 1994. It is a high-speed network technology for transferring data between workstations, mainframes, PCs, storage devices, supercomputers and other peripherals. One main objective of a FC is to provide a dependable interface for a remote operating system (OS) requiring a high bandwidth.
A G_Port supports a loop topology, which requires that all links be connected and operated at the same speed.
Techopedia explains Generic Port (G_Port)
A G_Port can operate as an E_Port or F_Port. The E_Port is an inter-switch expansion port used to connect two fiber switches. An F_Port is a fabric switch port used to connect an N_Port to a switch. Both the E_Port and F_Port are switch ports. A switch port can be an F_Port, FL_Port or E_Port. A switch is composed of several important components, such as:
An address manager
One or more switch ports
A router to transfer data packets
A path selector
A fabric controller to control data transfer
A switch construct having circuit switching, multiplexed frame switching or both
The functionality of a G_Port is determined during port login. If the G_Port is connected to a node, then it will operate like an F_Port. If the G_Port is connected to an expansion, it will function like an E_Port.
Most FC networks transmit small computer system interface commands using fiber channel networks, like a storage area network (SAN). The SAN is used for connecting servers, backup devices and disk arrays while possessing a very reliable redundant array of independent disks. If a server fails, then the additional server can support an array with a minimal loss of data and marginal downtime.