Web Management Guide-R05

Chapter 13 | Basic Administration Protocols
Ethernet Ring Protection Switching
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Figure 291: Sub-ring with Virtual Channel
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Sub-ring without R-APS Virtual Channel – Under certain circumstances it
may not be desirable to use a virtual channel to interconnect the sub-ring
over an arbitrary Ethernet network. In this situation, the R-APS messages
are terminated on the interconnection points. Since the sub-ring does not
provide an R-APS channel nor R-APS virtual channel beyond the
interconnection points, R-APS channel blocking is not employed on the
normal ring links to avoid channel segmentation. As a result, a failure at any
ring link in the sub-ring will cause the R-APS channel of the sub-ring to be
segmented, thus preventing R-APS message exchange between some of
the sub-ring’s ring nodes.
No R-APS messages are inserted or extracted by other rings or sub- rings at
the interconnection nodes where a sub-ring is attached. Hence there is no
need for either additional bandwidth or for different VIDs/Ring IDs for the
ring interconnection. Furthermore, protection switching time for a sub-ring
is independent from the configuration or topology of the interconnected
rings. In addition, this option always ensures that an interconnected
network forms a tree topology regardless of its interconnection
configuration. This means that it is not necessary to take precautions
against forming a loop which is potentially composed of a whole
interconnected network.
Figure 292: Sub-ring without Virtual Channel
◆ R-APS Def MAC – Sets the switch’s MAC address to be used as the node
identifier in R-APS messages. (Default: Enabled)
When ring nodes running ERPSv1 and ERPSv2 co-exist on the same ring, the
Ring ID of each ring node must be configured as “1”.
Sub-ring
with Virtual
Channel
Virtual
Channel
RPL Port
Interconnection Node
Ring Node
Major Ring
Sub-ring
with Virtual
Channel
RPL Port
Interconnection Node
Ring Node
Major Ring