A system to isolate a fault to a particular port from among multiple ports in a network. The network typically has a plurality of devices including hosts, storage units, and switch groups that intercommunicate via transceivers. A fault indication is received from one or more of the devices in the network. The fault indication is then processed with a chain of fault indication rules that have been linked together into a binary decision path based on a set of device rules and a data flow model for the network. This permits determining the particular port responsible for the fault, and reporting that port to a user of the network.