Patent ID: 8064353

Claim:
A communication device for detecting faults in at least either one of a first communication link and a second communication link constituting a set of physical lines connecting a first port of the communication device and a second port of a counterpart communication device, the first communication link being used for frame transfer from the communication device to the counterpart communication device, the second communication link being used for frame transfer from the counterpart communication device to the communication device, the communication device comprising: a frame transfer unit that communicates via the first communication link and the second communication link; a link confirmation frame sending unit that causes the frame transfer unit to send a link confirmation frame including a return identifier to judge whether it is necessary to reply and a specific MAC address that indicates the link confirmation frame for use in confirming a normal link status via the first communication link from the communication device to the counterpart communication device; and a return link confirmation frame monitoring unit that performs fault detection of the first and second communication links by monitoring a return link confirmation frame which is to be returned from the counterpart communication device to the communication device via the second communication link when the counterpart communication device receives the link confirmation frame via the first communication link; and a destination determination unit that determines whether or not a received packet is the a confirmation frame based on the specific MAC address for preferentially sending a link confirmation frame and that determines whether or not it is necessary to reply based on the return identifier.