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MAC address table entries allows paths to be switched quickly.
20.3.3 Operation when recovery is detected
The following figure shows operation when recovery from a ring fault is detected for a single
ring.
Figure 20-9 Operation during fault recovery
(1) Master node operation
When a ring fault has been detected, and a health check frame sent by the current node is
received, recovery from the ring fault is determined, and the following restoration
operations are performed:
1. The VLAN status of the ring for data transfer is changed.
The ring VLAN status for the secondary port is changed from Forwarding to Blocking.
The ring VLAN status when a recovery is detected is changed as shown in the
following table.
Table 20-3 VLAN status of rings for data transfer when a recovery is detected
Ring port
Primary port
Secondary port
2. Flush control frames are sent.
Flush control frames are sent from the primary port and secondary port of the master
node. Note that during recovery from the ring fault, any flush control frames
transferred by each transit node return to the master node, and are discarded.
3. The MAC address table is cleared.
The MAC address table entries pertaining to the ring port are cleared.
Clearing the MAC address table entries allows switching to the normal
communication path.
4. The monitoring status is changed.
When recovery from the ring fault is detected, the master node changes from the
recovery monitoring status to the fault monitoring status.
Before (normal)
Forwarding
Forwarding
20 Description of the Ring Protocol
After (fault)
Forwarding
Blocking
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