Rrpp Timers; How Rrpp Works - H3C S9500E Series Configuration Manual

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.
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The Hello timer specifies the interval at which the master node sends Hello packets out the
primary port.
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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.
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The Fast-Hello timer specifies the interval at which the master node sends Fast-Hello packets
out the primary port.
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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
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node through received Hello packets, to ensure 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.
Only main processing units suffixed with C (LSR1SRP2C1 for example) support the RRPP fast detection
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mechanism. Main processing units suffixed with B (LSR1SRP2B1 for example) do not support the
mechanism.

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.
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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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