Apparatus for constructing ring network

Abstract

A first communication apparatus to be coupled to a second communication apparatus and a third communication apparatus via a ring network, including: a first port to coupled to the ring network; and a second port to coupled to the ring network; wherein the first port and the second port is set to receive a control frame from the second communication apparatus and the third communication apparatus, and either the first port or the second port is set to be disabled to relay a user frame.

1 . A ring network system formed by a plurality of ring networks comprising a multi-ring network, wherein each of the ring networks comprises:
 a monitoring apparatus configured to monitor the ring network;   a first relay apparatus coupled to a shared link of the ring network; and   a second relay apparatus coupled to a non-shared link of the ring network,
 wherein each of the ring networks which share the shared link is set to either one of (1) a shared link monitored ring network in which the monitoring apparatus of the ring network monitors the associated ring network including the shared link and (2) a shared link non-monitored ring network in which the monitoring apparatus of the ring network monitors the associated ring network excluding the shared link, and 
   the monitoring apparatus of the shared link non-monitored ring network does not detect any failure occurring in the shared link.   
     
     
         2 . The ring network system according to  claim 1 , wherein:
 the monitoring apparatus of the shared link monitored ring network is configured to detect a failure occurring in at least one of the shared link of the associated ring network and the non-shared links of the associated ring network.   
     
     
         3 . The ring network system according to  claim 2 , wherein:
 the monitoring apparatus of the shared link monitored ring network includes a first ring port and a second ring port which are coupled to the associated ring network, either one of the first ring port and the second ring port is placed into a state of not sending and not transmitting user frames, and   when the monitoring apparatus detects a failure in the shared link monitored ring network, the first ring port and the second ring port are placed into a state of transmitting and receiving user frames.   
     
     
         4 . The ring network system according to  claim 1 , wherein:
 the first relay apparatus coupled to the shared link monitored ring network sends a frame in a predetermined direction of the associated ring network such that the monitoring apparatus can determine whether the failure occurring in the associated ring network is a failure in the shared link.