Repeater

A repeater in a communication network, the repeater comprising:

• a plurality of repeaters forming a ring shape topology, the ring shape topology realized by a connection of two specific ports among a plurality of ports in each of the plurality of repeaters;
• an address table registering a destination address of a connected device that is connected to each of the plurality of ports in each of the plurality of repeaters for a transfer of a frame in the communication network;
• and
• a communication controller controlling a transfer of a frame among the plurality of ports, from a receiving port by which the frame is received to a transmitting port from which the frame is transmitted and transmitting the frame from the transmitting port, the transfer of the frame in one repeater performed based on the destination address registered in the address table of the transmitting port that contains the same destination address of the connected device as the destination address in the received frame, wherein
• the plurality of repeaters establish the ring shape topology of the communication network by a connection of the two specific ports among the plurality of ports in one repeater respectively connected to one of the two specific ports in two other different repeaters,
• the address table registers the destination addresses of normal ports in each of the other repeaters in the communication network, the destination addresses of the normal ports representing destination devices connected to the normal ports that are the ports other than the specific ports in the other repeaters,
• the address table for each of the specific ports has a registration of additional information about a hop number representing a number of repeaters for the transmitted frame to pass through to reach from each of the specific ports to the connected device,
• the communication controller includes a determiner determining whether the destination address in the frame that is received by the normal port is registered in the address table of the specific port, and
• the communication controller includes, as a section that is operable when a positive determination yields from the determiner:
• a selector (i) comparing two hop numbers registered as the additional information in the address table in association with a destination address in the frame received by the normal port and (ii) selecting, as a transfer destination of the frame received by the normal port, a specific port for which the destination address with a smaller one of the two hop numbers is registered;
• and
• a transmitter transmitting the frame received by the normal port from the specific port selected by the selector.