R3303-HP HSR6800 Routers High Availability Configuration Guide

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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 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 might 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 might 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 from
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 generated by these
ports.
Broadcast storm suppression mechanism in case of SRPT failure in a multi-homed subring
As shown in Figure 21, 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 and causing a broadcast storm.
To avoid generating a loop, the edge node will temporarily block the edge port. The blocked edge port
is activated only when the edge node is sure that no loop will be generated when the edge port is
activated.
Load balancing
In a ring network, traffic from multiple VLANs might be transmitted at the same time. RRPP can implement
load balancing for the traffic by transmitting traffic from different VLANs along different paths.
By configuring an individual RRPP domain for transmitting the traffic from the specified VLANs (protected
VLANs) in a ring network, traffic from different VLANs can be transmitted according to different
topologies in the ring network for load balancing.
As shown in Figure 22, 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. Device
B is the master node of Ring 1 in Domain 2. With such configurations, traffic from different VLANs can
be transmitted on different links for 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 21, D
evice 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 need to send or receive Edge-Hello
packets frequently. If more subrings are configured or load balancing is configured for more multiple
domains, Device B and Device C will send or receive a mass of Edge-Hello packets.