A communication system includes: a first communication device configured to include first buffers to store data to be transmitted and received; a second communication device configured to include second buffers to store data to be transmitted and received; and a failure control device configured to include: an obtainment unit configured to obtain buffer usage state information to indicate a state of use of each of the first buffers and the second buffers from each of the first communication device and the second communication device; and an identification unit configured to identify a failure occurrence site on a channel, based on the obtained buffer usage state information, wherein the first communication device is configured to transmit and receive the data via the channel to and from the second communication device.