27.4.4 Operation when faults and restoration other than shared links occur in the shared link monitoring ring

The following explains faults and restoration other than for shared links in a shared link monitoring ring.

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(1) Actions when failures are detected

The following figure shows operation when a fault is detected other than for shared links in a shared link monitoring ring.

Figure 27-17: Operation in the event of a ring failure other than a shared link in a shared link monitoring ring

(a) Master node operation of shared link monitoring ring

When a fault is detected in a shared link monitoring ring, the master node can no longer receive HC(M)s from both directions, and detects a ring fault. As with a single ring, the following fault operations are performed for the master node detecting the fault:

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

Flush control frames are sent.

The MAC address table is cleared.

The monitoring status is changed.

(b) Transit Node Operation for Shared Link Monitoring Ring

As with single rings, the following operations are performed when a flush control frame sent from the master node is received:

Flush control frames are transferred.

The MAC address table is cleared.

(c) Master and Transit Nodes (Shared Nodes) Behavior for Shared Link Non-Monitoring Rings

Because no faults occur within a shared link non-monitoring ring, fault operation is not performed.

(2) Operation when recovery is detected

The following figure shows operation for recovery from a fault other than for shared links in a shared link monitoring ring.

Figure 27-18: Operation when recovering from a ring failure other than a shared link in a shared link monitoring ring

(a) Master node operation of shared link monitoring ring

When a ring fault has been detected, and the master node receives an HC(M) it sent itself, it determines that recovery from the ring fault has occurred. As with a single ring, the following restoration operations are performed:

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

Flush control frames are sent.

The MAC address table is cleared.

The monitoring status is changed.

(b) Transit Node Operation for Shared Link Monitoring Ring

As with single rings, the following operations are performed when a flush control frame sent from the master node is received:

Flush control frames are transferred.

The MAC address table is cleared.

(c) Master and Transit Nodes (Shared Nodes) Behavior for Shared Link Non-Monitoring Rings

Because faults do not occur within a shared link non-monitoring ring, restoration is not performed.