ECS4110-28T_Management Guide

C HAPTER 14 | Basic Administration Protocols
Ethernet Ring Protection Switching
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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.
◆ Major Domain – The ERPS ring used for sending control packets.
This switch can support up to six rings. However, ERPS control packets
can only be sent on one ring. This parameter is used to indicate that
the current ring is a secondary ring, and to specify the major ring which
will be used to send ERPS control packets.
The Ring Protection Link (RPL) is always the west port. So the physical
port on a secondary ring must be the west port. In other words, if a
domain has two physical ring ports, this ring can only be a major ring,
not a secondary ring (or sub-domain) which can have only one physical
ring port. The major domain therefore cannot be set if the east port is
already configured.
◆ Node ID – A MAC address unique to the ring node. The MAC address
must be specified in the format xx-xx-xx-xx-xx-xx or xxxxxxxxxxxx.
(Default: CPU MAC address)
The ring node identifier is used to identify a node in R-APS messages
for both automatic and manual switching recovery operations.
For example, a node that has one ring port in SF condition and detects
that the condition has been cleared, will continuously transmit R-APS
(NR) messages with its own Node ID as priority information over both
ring ports, informing its neighbors that no request is present at this
node. When another recovered node holding the link blocked receives
this message, it compares the Node ID information with its own. If the
received R-APS (NR) message has a higher priority, this unblocks its
ring ports. Otherwise, the block remains unchanged.
The node identifier may also be used for debugging, such as to
distinguish messages when a node is connected to more than one ring.
◆ 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)
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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.
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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