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VLANs and sending Common-Flush-FDB packets to instruct all transit nodes to update their own
MAC entries and ARP/ND entries.
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 of its own ports belonging to an RRPP domain are down. Upon the
receipt of a Link-Down packet, the master node releases the secondary port from blocking data VLANs
and sending Common-Flush-FDB packet to instruct all the transit nodes, the edge nodes, and the
assistant-edge nodes to update their own MAC entries and ARP/ND entries. After each node updates its
own entries, traffic is switched to the normal link.
Ring recovery
The master node may find that the ring is restored after a period of time after the ports belonging to the
RRPP domain on the transit nodes, the edge nodes, or the assistant-edge nodes are brought up again. A
temporary loop may arise in the data VLAN during this period. As a result, broadcast storm occurs.
To prevent temporary loops, non-master nodes block them immediately (and permit only the packets of
the control VLAN to pass through) when they find their ports accessing the ring are brought up again.
The blocked ports are activated only when the nodes are sure that no loop will be brought forth by these
ports.
Broadcast storm suppression mechanism in a multi-homed subring in case of SRPT failure
As shown in Figure 15, Ring 1 is the primary ring, and Ring 2 and Ring 3 are subrings. When the two
SRPTs 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, generating a loop among Device B, Device C, Device
E, and Device F. As a result, a broadcast storm occurs.
To prevent generating this loop, the edge node will block the edge port temporarily. The blocked edge
port is activated only when the edge node is sure that no loop will be brought forth when the edge port
is activated.
Load balancing
In a ring network, maybe traffic of multiple VLANs is transmitted at the same time. RRPP can implement
load balancing for the traffic by transmitting traffic of different VLANs along different paths.
By configuring an individual RRPP domain for transmitting the traffic of the specified VLANs (protected
VLANs) in a ring network, traffic of different VLANs can be transmitted according to different topologies
in the ring network. In this way, load balancing is achieved.
As shown in Figure 16, R
ing 1 is configured as the primary ring of Domain 1 and Domain 2, which are
configured with different protected VLANs. Device A is the master node of Ring 1 in Domain 1, and
Device B is the master node of Ring 1 in Domain 2. With such configurations, traffic of different VLANs
can be transmitted on different links to achieve load balancing in the single-ring network.
RRPP ring group
In an edge node RRPP ring group, only an activated subring with the lowest domain ID and ring ID can
send Edge-Hello packets. In an assistant-edge node RRPP ring group, any activated subring that has
received Edge-Hello packets will forward these packets to the other activated subrings. With an edge
node RRPP ring group and an assistant-edge node RRPP ring group configured, only one subring sends
Edge-Hello packets on the edge node, and only one subring receives Edge-Hello packets on the
assistant-edge node, reducing CPU workload.
As shown in Figure 15,
Device B is the edge node of Ring 2 and Ring 3, and Device C is the
assistant-edge node of Ring 2 and Ring 3. Device B and Device C must send or receive Edge-Hello
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