InterSwitch Trunk

InterSwitch Trunk (IST) is one or more parallel point-to-point links (Link aggregation) that connect two switches together to create a single logical switch. The IST allows the two switches to share addressing information, forwarding tables, and state information, permitting rapid (less than one second) fault detection and forwarding path modification. The link may have different names depending on the vendor. For example, Brocade calls this an Inter-Chassis Link (ICL). Cisco calls this a VSL (Virtual Switch Link).