Patent ID: 8521884

Claim:
A network system, comprising: a network; a plurality of virtual machines, each of the virtual machines comprising an Internet protocol (IP) address and N media access control (MAC) addresses, so as to connect the network through N transmission routes, wherein N is a positive integer and N>1; a routing module, for detecting and calculating states of the transmission routes; and a path directory server, for recording the IP address and the N MAC addresses of each of the virtual machines and a calculation result of the routing module, and receiving and decoding an address resolution protocol (ARP) request presented by at least one source virtual machine to reply path information, wherein the path information comprises N MAC addresses corresponding to the IP address of a destination virtual machine and states of the N transmission routes, the at least one source virtual machine is one of the virtual machines, and the destination virtual machine is another one of the virtual machines, wherein, the path directory server transmits a timestamp to each of the at least one source virtual machine when replying the path information, wherein the at least one source virtual machine removes the path information after the timestamp becomes invalid, wherein the path directory server records a physical machine identification code corresponding to each of the at least one source virtual machine and the corresponding timestamp, and removes the physical machine identification code and the corresponding timestamp after the timestamp becomes invalid, wherein when the states of the transmission routes are changed and the timestamp is still valid, the path directory server actively notifies each of the at least one source virtual machine to update the states of the N transmission routes in the path information.