How Rrpp Works - HP A5120 EI Configuration Manual

How RRPP works

Polling mechanism
The polling mechanism is used by the master node of an RRPP ring to check the Health state of the ring
network.
The master node sends Hello packets out its primary port periodically. These Hello packets travel through
each transit node on the ring in turn.
If the ring is complete, the secondary port of the master node will receive Hello packets before the

Fail timer expires, and the master node will keep the secondary port blocked.
If the ring is torn down, the secondary port of the master node will fail to receive Hello packets

before the Fail timer expires. The master node will release the secondary port from blocking data
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
When a transit node, edge node, or assistant-edge node finds that any of its own ports belonging to an
RRPP domain are down, it immediately sends Link-Down packets to the master node. Upon the receipt of
a Link-Down packet, the master node releases the secondary port from blocking data VLANs, and sends
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
After the ports belonging to the RRPP domain on the transit nodes, the edge nodes, or the assistant-edge
nodes are brought up again, the master node may find that the ring is restored after a period of time. A
temporary loop may arise in the data VLAN during this period, resulting in a broadcast storm.
To prevent temporary loops, when non-master nodes find that their ports accessing the ring are brought
up again, they block them immediately and permit only the packets of the control VLAN to pass through.
The blocked ports are activated only when the nodes are sure that the ports will not cause a loop.
Broadcast storm suppression mechanism in case of SRPT failure in a multi-homed subring
As shown in
SRPTs between the edge node and the assistant-edge node are down, the master nodes of Ring 2 and
Ring 3 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 temporarily blocks the edge port. The blocked edge port
is activated only when the edge node is sure that activating it will not cause a loop.
Load balancing
In a ring network, traffic of multiple VLANs may be 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
configured with different protected VLANs. Device A is the master node of Ring 1 in Domain 1, and
Figure 17, Ring 1 is the primary ring, and Ring 2 and Ring 3 are subrings. When the two
Figure 18, Ring 1 is configured as the primary ring of Domain 1 and Domain 2, which are
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