Patent ID: 8767736

Claim:
A communication device comprising: a transfer unit transferring a received frame based on an identifier included in the received frame; a calculation unit calculating a size of the received frame to which the identifier is added when the received frame is a specific frame; a notification unit adding a value indicating a transmittable size or a size less than the transmittable size, when the size of the received frame after the identifier added is larger than the size that can be transmitted to a next destination communication device on a communication path, generating a transmission impossible notification frame addressed to a source communication device of the received frame, and transferring the transmission impossible notification frame to the transfer unit; a retransmission unit correcting the size of the specific frame to be smaller than or equal to the transmittable size, when the transmission impossible notification frame is received, and transferring the specific frame having been corrected to the transfer unit for retransmission; a transmittable size storage unit storing the value indicating the transmittable size or a size less than the transmittable size stored in the transmission impossible notification frame, when the transmission impossible notification frame is received; and a transmission availability determination unit comparing the transmittable size with the size of the received frame after the identifier added, by referring to the transmittable size storage unit, and determining whether the size of the received frame after the identifier added is the transmittable size.