Web Management Guide-R05

Table Of Contents
Chapter 13
| Basic Administration Protocols
Ethernet Ring Protection Switching
– 457
the ring port which was blocked as a result of an operator
command.
Recovery with non-revertive mode is handled as follows:
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 Clear command (Configure
Operation page) at the RPL Owner Node, this ring node blocks
the ring port attached to the RPL, transmits an R-APS (NR, RB)
message on 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.
Recovery for Manual Switching – A Manual Switch command is
removed by issuing the Clear command (Configure Operation
page) at the same ring node where the Manual Switch is in
effect. The clear command removes any existing local operator
commands, and triggers reversion if the ring is in revertive
behavior mode.
The ring node where the Manual Switch was cleared keeps the
ring port blocked for the traffic channel and for the R-APS
channel, due to the previous Manual Switch command. This ring
port is kept blocked until the RPL is blocked 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.
Recovery with revertive mode is handled as follows:
a.
The RPL Owner Node, upon reception of an R-APS (NR)
message and in the absence of any other higher priority