29.6.5 Operation for Multiple Fault Recovery

A shared node receives a multi-fault monitoring frame sent from an opposing shared node, and detects multi-fault recovery.

The shared node that detected multi-fault recovery starts sending backup ring HC(S)s again.

When the master node receives HC(S)s sent by shared nodes from both directions, it determines that recovery from the ring fault has occurred, and performs restoration operations. The operation of the master node and transit node when recovery is detected is the same as that when multiple rings are used. For details, see section 29.4.3, Operation When Detecting Recovery from Failures or Restorations Other Than Shared Links in a Shared Link Non-Monitoring Ring (2).

When shared nodes receive a flush control frame from the master node of the backup ring, they send to the shared link monitoring ring only flush control frames that clear the MAC address table.

Transit nodes receive flush control frames sent from shared nodes, and clear the MAC address table.

Blocking is maintained for the ring VLAN status of the ring ports after recovery from the link fault, because the master node has not detected ring restoration.

For details on releasing blocking, see "29.8 Ring Protocol Usage Notes (17) Communication when Recovering Part of Multiple Failures".

When the master node receives an HC(M) sent by itself, it determines that recovery from the ring fault has occurred, and performs restoration. The operation of the master node and transit node at recovery detection is the same as that at multi-ring. For details, refer to section 29.4.2, Operation at Shared Link Failure and Recovery (2), Operation at Recovery Detection.

Transit nodes receive flush control frames sent from the master node, and clear the MAC address table.

When transit nodes receive flush control frames sent from the master node, they change the ring VLAN status of the ring port after recovery from the link fault to Forwarding.