user manual

11-22
Cisco ONS 15454 SDH Reference Manual, R5.0
April 2008
Chapter 11 SDH Topologies and Upgrades
11.4.2 SNCP Dual Ring Interconnect
11.4.2 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 SDHs at the interconnect nodes, while the
integrated DRI uses two nodes.
Figure 11-21 shows ONS 15454 SDHs 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.