Rrpp Timers; How Rrpp Works - 3Com S7906E Configuration Manual

RRPPDUs of subrings are transmitted as data packets in the primary ring, while RRPPDUs of the
primary ring can only be transmitted within the primary ring.

RRPP Timers

When RRPP checks the link state of an Ethernet ring, the master node sends Hello packets out the
primary port according to the Hello timer and determines whether its secondary port receives the Hello
packets based on the Fail timer.
The Hello timer specifies the interval at which the master node sends Hello packets out the primary
port.
The Fail timer specifies the maximum delay between the master node sending Hello packets out
the primary port and the secondary port receiving the Hello packets from the primary port. If the
secondary port receives the Hello packets sent by the local master node before the Fail timer
expires, the overall ring is in Health state. Otherwise, the ring transits into Disconnect state.
The Fast-Hello timer specifies the interval at which the master node sends Fast-Hello packets out
the primary port.
The Fast-Fail timer specifies the maximum delay between the master node sending Fast-Hello
packets out the primary port and the secondary port receiving the Fast-Hello packets from the
primary port. If the secondary port receives the Fast-Hello packets sent by the local master node
before the Fast-Fail timer expires, the entire ring is in Health state. Otherwise, the ring transits into
Disconnect state.
In an RRPP domain, a transit node learns the Hello timer value and the Fail timer value on the master
node through the received Hello packets, ensuring that all nodes in the ring network are consistent in
the two timer settings. A transit node, however, cannot learn the Fast-Hello timer value and the
Fast-Fail timer value set on the master node through received Fast-Hello packets.

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, 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.
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