Patent ID: 8458551

Claim:
A verification device comprising: a data verifying unit that verifies a presence or absence of an error of data included in a packet by using one of a first verification mode for verifying a presence or absence of an error of data included in a first packet received and a second verification mode for verifying a presence or absence of an error of data included in a second packet received immediately before the first packet; a packet generating unit that generates a packet by using one of a first packet generation mode for generating a packet corresponding to the first verification mode and a second packet generation mode for generating a packet corresponding to the second verification mode; a failure monitoring unit that monitors whether a failure of a transmission line that requires a switching of the verification mode occurs; a switching packet transmitting unit that transmits, to a first verification device, which is a packet transmission destination, a switching packet for informing of the switching of the verification mode that is used by the data verifying unit when the failure monitoring unit detects an occurrence of a failure or a removal of a failure; a generation mode switching unit that switches the generation mode that is used by the packet generating unit; and a verification mode switching unit that switches the verification mode that is used by the data verifying unit to the verification mode informed by the switching packet when receiving the switching packet, wherein the switching packet transmitting unit transmits the switching packet including data for switching the verification mode from the second verification mode to the first verification mode and subsequently transmits a null packet in which data is not stored.