5-6
z
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 while 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 is
down. Upon the receipt of a Link-Down packet, the master node releases the secondary port
from blocking data VLANs while 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 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
, 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, and thus a loop among
Device B, Device C, Device E, and Device F is generated. As a result, broadcast storm occurs.
In this case, 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
(referred to as 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
, Ring 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; 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, and thus, load balancing is achieved in
a single-ring network.
