27.3.2 Actions when failures are detected

The following figure shows operation when a ring fault has been detected for a single ring.

Figure 27-8: Operation when a ring error occurs

<Structure of this section>

(1) Master node operation

A fault is determined to have occurred when health check frames in both directions are not received within the pre-determined time. Switching operation is performed as follows on the master node that detects the fault:

The VLAN status of the ring for data transfer is changed.

The ring VLAN status for the secondary port is changed from Blocking to Forwarding. The ring VLAN status when a fault is detected is changed as shown in the following table.

Table 27-2: VLAN status for transferring data when a failure is detected
Ring port	Before (normal)	After (fault)
Primary port	Forwarding	Forwarding
Secondary port	Blocking	Forwarding

Flush control frames are sent.

Flush control frames are sent from the primary port and secondary port of the master node.

The MAC address table is cleared.

Clears MAC address table entry. Clearing the MAC address table entries allows paths to be switched quickly.

The monitoring status is changed.

When a ring fault is detected, the master node changes from the fault monitoring status to the recovery monitoring status.

(2) Transit node operation

The following operation is performed on a transit node that receives a flush control frame sent from a master node detecting a fault:

Flush control frames are transferred.: Any received flush control frames are transferred to the next node.
The MAC address table is cleared.: Clears MAC address table entry. Clearing the MAC address table entries allows paths to be switched quickly.