R3102-R3103-HP 6600/HSR6600 Routers High Availability Configuration Guide

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 of its primary port periodically, and 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

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.