CLI Reference Guide-R05

Chapter 18 | ERPS Commands
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as a result of ring protection reversion, or until there is another higher priority
request (e.g., an SF condition) in the ring.
The Ethernet Ring Node where the Manual Switch was cleared continuously
transmits the R-APS (NR) message on both ring ports, informing that no request
is present at this ring node. The ring nodes stop transmitting R-APS (NR)
messages when they accept an RAPS (NR, RB) message, or when another higher
priority request is received.
If the ring node where the Manual Switch was cleared receives an R-APS (NR)
message with a Node ID higher than its own Node ID, it unblocks any ring port
which does not have an SF condition and stops transmitting R-APS (NR)
message on both ring ports.
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Recovery with revertive mode is handled in the following way:
a. The RPL Owner Node, upon reception of an R-APS (NR) message and in
the absence of any other higher priority request, starts the WTB timer
and waits for it to expire. While the WTB timer is running, any latent R-
APS (MS) message is ignored due to the higher priority of the WTB
running signal.
b. When the WTB timer expires, it generates the WTB expire signal. The
RPL Owner Node, upon reception of this signal, initiates reversion by
blocking the traffic channel on the RPL, transmitting an R-APS (NR, RB)
message over both ring ports, informing the ring that the RPL is
blocked, and flushes its FDB.
c. The acceptance of the R-APS (NR, RB) message causes all ring nodes to
unblock any blocked non-RPL that does not have an SF condition. If it is
an R-APS (NR, RB) message without a DNF indication, all Ethernet Ring
Nodes flush their FDB. This action unblocks the ring port which was
blocked as a result of an operator command.
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Recovery with non-revertive mode is handled in the following way:
a. The RPL Owner Node, upon reception of an R-APS (NR) message and in
the absence of any other higher priority request does not perform any
action.
b. Then, after the operator issues the erps clear command at the RPL
Owner Node, this ring node blocks the ring port attached to the RPL,
transmits an R-APS (NR, RB) message over both ring ports, informing
the ring that the RPL is blocked, and flushes its FDB.
c. The acceptance of the R-APS (NR, RB) message triggers all ring nodes to
unblock any blocked non-RPL which does not have an SF condition. If it
is an R-APS (NR, RB) message without a DNF indication, all ring nodes
flush their FDB. This action unblocks the ring port which was blocked as
result of an operator command.