FC topologies and port types

The following types of ports are defined by Fibre Channel:

N_port is a port on the node (e.g. host or storage device) used with both FC-P2P or FC-SW topologies. Also known as Node port.

NL_port is a port on the node used with an FC-AL topology. Also known as Node Loop port.

F_port is a port on the switch that connects to a node point-to-point (i.e. connects to an N_port). Also known as Fabric port. An F_port is not loop capable.

FL_port is a port on the switch that connects to a FC-AL loop (i.e. to NL_ports). Also known as Fabric Loop port.

E_port is the connection between two fibre channel switches. Also known as an Expansion port. When E_ports between two switches form a link, that link is referred to as an inter-switch link (ISL).

EX_port is the connection between a fibre channel router and a fibre channel switch. On the side of the switch it looks like a normal E_port, but on the side of the router it is a EX_port.

TE_port * a Cisco addition to Fibre Channel, now adopted as a standard. It is an extended ISL or EISL. The TE_port provides not only standard E_port functions but allows for routing of multiple VSANs (Virtual SANs). This is accomplished by modifying the standard Fibre Channel frame (vsan tagging) upon ingress/egress of the VSAN environment. Also known as Trunking E_port.

VE_Port an INCITS T11 addition, FCIP interconnected E-Port/ISL, i.e. fabrics will merge.

VEX_Port a INCITS T11 addition, is a FCIP interconnected EX-Port, routing needed via lsan zoning to connect initiator to a target.

General (catch-all) types

Auto or auto-sensing port found in Cisco switches, can automatically become an E_, TE_, F_, or FL_port as needed.

Fx_port a generic port that can become a F_port (when connected to a N_port) or a FL_port (when connected to a NL_port). Found only on Cisco devices where oversubscription is a factor.

G_port or generic port on a switch can operate as an E_port or F_port. Found on Brocade and McData switches.

L_port is the loose term used for any arbitrated loop port, NL_port or FL_port. Also known as Loop port.

U_port is the loose term used for any arbitrated port. Also known as Universal port.

June 30, 2011

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