Web Management Guide-R02

Table Of Contents
Chapter 13
| Basic Administration Protocols
Ethernet Ring Protection Switching
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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.
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 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.
R-APS with VC – Configures an R-APS virtual channel to connect two
interconnection points on a sub-ring, allowing ERPS protocol traffic to be
tunneled across an arbitrary Ethernet network. (Default: Enabled)
A sub-ring may be attached to a primary ring with or without a virtual
channel. A virtual channel is used to connect two interconnection points
on the sub-ring, tunneling R-APS control messages across an arbitrary
Ethernet network topology. If a virtual channel is not used to cross the
intermediate Ethernet network, data in the traffic channel will still flow
across the network, but the all R-APS messages will be terminated at the
interconnection points.
Sub-ring with R-APS Virtual Channel – When using a virtual channel to
tunnel R-APS messages between interconnection points on a sub-ring, the
R-APS virtual channel may or may not follow the same path as the traffic
channel over the network. R-APS messages that are forwarded over the
sub-ring’s virtual channel are broadcast or multicast over the
interconnected network. For this reason the broadcast/multicast domain of
the virtual channel should be limited to the necessary links and nodes. For
example, the virtual channel could span only the interconnecting rings or
sub-rings that are necessary for forwarding R-APS messages of this sub-
ring. Care must also be taken to ensure that the local RAPS messages of the