Relay system and switching device

A relay system, comprising:

• a plurality of port switches;
• and
• a plurality of fabric switches functioning to relay a frame between the plurality of port switches,
• wherein each of the plurality of port switches is connected to each of the plurality of fabric switches by links,
• each of the plurality of fabric switches is configured to:
• detect a fault of links connected to itself;
• when a fault is detected, generate a first fault notification frame containing a fault link identifier representing a link having the fault;
• and
• transmit the first fault notification frame to the plurality of port switches, and flood a second fault notification frame when the second fault notification frame is received from any of the plurality of port switches,
• each of the plurality of port switches is configured to:
• detect a fault of links connected to itself;
• when a fault is detected, generate the second fault notification frame containing a fault link identifier representing a link having the fault;
• transmit the second fault notification frame to the plurality of fabric switches;
• and
• when the first fault notification frame or the second fault notification frame is received at all of links connected to itself, set LAG to the links connected to itself based on the fault link identifier contained in the received fault notification frame.