27.4.3 Operation when faults and restoration other than shared links occur in a shared link non-monitoring ring

The following explains faults and restoration other than for shared links, for shared link non-monitoring rings.

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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 on shared link non-monitoring rings.

Figure 27-15: Operation in the event of a ring failure other than a shared link in a shared link non-monitoring ring

(a) Master node operation for shared link non-monitoring ring

The master node of a shared link non-monitoring ring detects a ring fault when it receives neither the two-way HC(M) sent by itself nor the HC(S) sent by a shared node. As with a single ring, the following 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 and Shared Node Behavior for Shared Link Non-Monitoring Rings

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 Node and Transit Node Operation for Shared Link Monitoring Ring

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

(2) Operation when recovery is detected

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

Figure 27-16: Operation when recovering from a ring failure other than a shared link in a shared link non-monitoring ring

(a) Master node operation for shared link non-monitoring ring

When a ring fault has been detected, and either the master node receives an HC(M) that it sent itself, or an HC(S) sent by shared nodes are received from both directions, recovery from the ring fault is determined. 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 and Shared Node Behavior for Shared Link Non-Monitoring Rings

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 Node and Transit Node Operation for Shared Link Monitoring Ring

Because no faults occur within a shared link monitoring ring, restoration is not performed.