Specifications

ALAXALA Ring Configuration Guide (Edition 1)

2.2.3 Operation during recovery from a failure

When a failure is resolved in a single ring, the Ring Protocol works as follows:

Figure 2.2-3 Single ring operation during recovery from a failure

(1) Master node operation

When a failure is resolved in the ring, the master node takes the following actions:

[1] Changing the status of the ring VLAN for data transfer

The master node changes the status of the secondary port used for the ring VLAN group for data

transfer to the BLK status.

After recovery from a failure is detected in the ring, the ring VLAN statuses of the master node are as

follows:

Ring port (primary): FWD (not changed)

Ring port (secondary): FWD -> BLK

[2] Sending flush control frames

When the master node detects recovery from a failure in the ring, the node sends flush control frames

from its two ring ports.

The master node sends the flush control frames several times from each ring port to ensure that the frames

are actually sent out.

[3] Clearing the MAC address table

Similarly to the operation after ring failure detection, the MAC address table entries are cleared only if

an entry has an output VLAN that belongs to the ring VLAN group for data transfer and its output

destination is a ring port.

[4] Receiving flush control frames

After the ring has recovered, flush control frames are forwarded by transit nodes and finally come back

to the master node. The master node discards the returned flush control frames.

[5] Transition of the ring status to the failure monitoring status (change in monitoring status)

After the master node detects recovery from the failure of the ring, the master node status changes from

the recovery monitoring status to the failure monitoring status.

(2) Transit node operation

During recovery from a ring failure, a transit node receives several flush control frames on the ring port. A

transit node performs steps [1] and [2] below when the first flush control frame arrives. Then, when the transit

node receives the subsequent flush control frames during step [2], the node performs step [3]. If the node receives

the subsequent frames after step [2] is completed, the node clears the table again.

[1] Forwarding of flush control frames to the next destination

[2] Clearing the MAC address table

The MAC address table entries whose output destination is one of the ring ports are cleared.

[3] Forwarding flush control frames to the next node without clearing the MAC address table

The failure is recovered.

Rin

VLAN: FWD -> BLK

T1 M T5

T2 T3 T4

Flush control

frames