A network device is configured to: detect a virtual network that is unable to relay communication as a failed virtual network; identify, as a failed virtual network identifier, a virtual network identifier assigned to a combination of the failed virtual network and a physical port through which communication of the failed virtual network pass, based on mapping information; identify a first virtual tunnel end point that relays communication of the failed virtual network; identify a second virtual tunnel end point of another network device that communicates with the first virtual tunnel end point based on the tunnel information; and send, to the second virtual tunnel end point, a clear request including the failed virtual network identifier and an IP address of the first virtual tunnel end point, and the clear request being used for clearing a MAC address used in Layer 2 protocol.