inter switch link (ISL)
- The Inter SwitchLink Protocol (ISL) is a protocol developed by Cisco for Ethernet and Token Ring LANs. The ISL protocol encapsulates Ethernet or Token Ring data packets and transports them between two switches or routers on a point-to-point link. ISL tagging performs the same function as 802.1Q trunking, but uses a different frame format. ISL frame tagging uses a low- latency mechanism to multiplex traffic from multiple VLANs onto one physical line.
- In Fibre Channel, the physical connection between multiple FC switches is called Inter Switch Links (ISL). All fabrics communicating with each other via the inter switch links together form the star point in the star-shaped FC topology.