US Patent 9130867 Flow control for virtualization-based server

A server includes a processor, a network adapter connected to the processor and a route switcher. The processor includes a virtual machine and a virtual switch relaying packets exchanged between the virtual machine and an exterior. The network adapter has a transfer function of transmitting and receiving packets to and from the virtual machine not through the virtual switch. The route switcher dynamically switches a flow of the packets transmitted and received by the virtual machine between first and second route pattern flows. And, the route switcher instructs the transfer function to process the first route pattern flow instructs the virtual switch to process the second route pattern flow.