Patent ID: 7706270

Claim:
A communication control method in a communication system performing transmission/reception of data between end hosts connected to a relay switch in a subnet, for recovering a communication failure due to a packet loop generated by an improper connection at an L2 level in the relay switch, the method comprising: monitoring a number of reception packets per unit of time; continuously transmitting long-size MAC packets longer than a packet generating the packet loop into the subnet by a control apparatus that generates the long-size MAC packets and is connected to the communication system until the monitored number of the reception packets per unit of time becomes a predetermined value or less after at least one long-size MAC packet has been transmitted, the long-size MAC packets having destinations as a broadcast MAC address or multicast MAC address and, if the packet generating the packet loop has the longest size MAC packet possible in the system, the long-size MAC packets will have the longest size possible in the system; and overflowing an input or output queue and discarding the packet generating the packet loop by the relay switch receiving the long-size MAC packets because of the transmission of the long-size MAC packets.