Qtech QSW-2900-24T-AC [195/209] Protocols and standards

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16.5.2 Link down alarm mechanism
The transit node, the edge node or the assistant edge node sends Link-Down packets to the master node
immediately when they find any port belonging to an ERRP domain is down. Upon the receipt of a Link-Down
packet, the master node releases the secondary port from blocking data VLAN while sending Common-Flush-FDB
packet to notify all the transit nodes, the edge nodes and the assistant nodes to update their own MAC entries and
ARP entries.
16.5.3 Ring recovery
The master node may find the ring is restored after a period of time after the ports belonging to the ERRP
domain on the transit node, the edge node or the assistant edge node are up again. A temporary loop may arise in the
data VLAN in this period. As a result, broadcast storm occurs.
To prevent temporary loops, non-master nodes block them immediately (and permits only the packets of the
control VLAN) when they find their ports accessing the ring are up again. The blocked ports are activated only when
the nodes ensure that no loop will be brought forth by these ports.
16.5.4 Broadcast storm suppression mechanism in a
multi-homed subring in case of primary ring link failure
As shown in Figure 5, Ring 1 is the primary ring, and Ring 2 and Ring 3 are subrings. When two links of the
primary ring between the edge node and the assistant edge node are down, the master nodes of Ring 2 and Ring 3
will open their respective secondary ports, and thus a loop among B, C, E and F is generated. As a result, broadcast
storm occurs.
In this case, to prevent from generating this loop, the edge node will block the edge port temporarily. The
blocked edge port is activated only when the edge node ensures that no loop will be brought forth when the edge port
is activated.
16.5.5 Protocols and Standards
Related standard: RFC 3619.
16.6 ERRP Configuration
16.6.1 ERRP Configuration list
Only when ERRP and ring enable, the configuration can be effective.theconfiguration will be reserved when
ERRP and ring disable and it will be effective when ERRP and ring enable next time.
· ERRP configuration
· Configure ERRP timer
· Enter ERRP configuration mode
· Create ERRP ring
· Enable/disable ERRP ring

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