Patent ID: 8032793

Claim:
A method of controlling an information processing system including a plurality of information processing devices connected to a router, the router including a plurality of input/output ports, each of which respectively function as an upstream port with a first property or as a downstream port with a second property, the method comprising: sending update start notice for causing all of the information processing devices to halt data transmission when a fault occurs in an information processing device connected to an upstream one of the input/output ports; checking whether a data transfer process between the information processing devices exists; sending a confirmation notice that indicates a reception of the update start notice in response to the update start notice when a result of the checking indicates that the data transfer process does not exist; completing the data transfer process and sending the confirmation notice after the data transfer process is completed when the result of the checking indicates that the data transfer process exists; selecting a downstream one of the input/output ports to become the upstream port after receiving the confirmation notice; assigning new port numbers using the selected upstream port as a reference; and instructing the information processing devices to restart the data transmission after the assignment of the new port numbers.