Datasheet

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Cisco ONS 15454 SDH Reference Manual, R7.0
October 2008
Chapter 12 SDH Topologies and Upgrades
12.4.2 SNCP Dual Ring Interconnect
Figure 12-20 ONS 15454 SDH Integrated MS-SPRing Dual Ring Interconnect
12.4.2 SNCP Dual Ring Interconnect
The SNCP dual ring interconnect topology (SNCP DRI) provides an extra level of path protection
between interconnected SNCP rings. In DRIs, traffic is dropped and continued at the interconnecting
nodes to eliminate single points of failure. Two DRI topologies can be implemented on the
ONS 15454 SDH. The traditional DRI uses four ONS 15454 SDH nodes at the interconnect nodes, while
the integrated DRI uses two nodes.
Figure 12-21 shows ONS 15454 SDH nodes in a traditional DRI topology. In Ring 1, Nodes 4 and 5 are
the interconnect nodes, and in Ring 2, Nodes 6 and 7 are the interconnect nodes. Duplicate signals are
sent from Node 4 (Ring 1) to Node 6 (Ring 2), and between Node 5 (Ring 1) and Node 7 (Ring 2). In
Ring 1, traffic at Node 4 is dropped (to Node 6) and continued (to Node 5). Similarly, at Node 5, traffic
is dropped (to Node 7) and continued (to Node 4).
To route circuits on the DRI, you must choose the DRI option during circuit provisioning. Circuits with
the DRI option enabled are routed on the DRI path.
Service Selector
Secondary Path (protection)
Primary Path (working)
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MS-SPRing 1
Primary
Secondary
MS-SPRing 2
Node 8
Node 3
Node 1 Node 2
Node 6Node 7
Node 5
Node 4