Which interface should be used for interconnecting FC switches

E_Ports and EX_Ports are the primary interfaces used to interconnect FC switches, forming inter-switch links (ISLs) or inter-fabric links (IFLs) in a SAN. E_Ports (Expansion Ports)E_Ports are specialized Fibre Channel switch ports used to connect one FC switch to another, creating an inter-switch link (ISL). These links allow multiple switches to form a single fabric, enabling devices connected to different switches to communicate seamlessly.

E_Ports participate in fabric services, including name server registration, zoning, and fabric topology propagation, ensuring that all switches in the fabric are aware of connected devices and paths. EX_Ports (Extended Ports)EX_Ports are similar to E_Ports but are used specifically in inter-fabric connections. They terminate at the switch and do not propagate fabric services or routing information from one fabric to another.

EX_Ports are typically used when connecting edge fabrics to a backbone fabric or when implementing metaSAN architectures with multiple independent fabrics. EX_Ports form inter-fabric links (IFLs), which allow controlled communication between fabrics without merging them, maintaining separate zoning and access controls.

Inter-

Fabric Links (IFLs)An IFL is the logical link between an E_Port on one fabric and an EX_Port on another fabric.

IF

Ls are used to connect edge fabrics to backbone fabrics or to interconnect multiple SAN fabrics in a metaSAN configuration.

Multiple IF

Ls can be configured for redundancy and load balancing, ensuring high availability and fault tolerance.

Best Practices

Always use redundant E_Ports or EX_Ports to interconnect switches to avoid a single point of failure. Maintain separate fabrics for redundancy; do not combine fabrics unless using proper inter-fabric links. Follow switch vendor guidelines for port configuration, zoning, and fabric topology to ensure compatibility and optimal performance.

In summary, E_Ports are used for standard inter-switch connections within a single fabric, while EX_Ports are used for controlled inter-fabric connections. Configuring these ports correctly ensures a resilient, high-performance SAN with proper device communication and zoning.