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Cisco ONS 15454 Reference Manual, R8.5.x
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Chapter 12 SONET Topologies and Upgrades
12.4.1 BLSR DRI
Figure 12-19 shows ONS 15454 nodes in a traditional BLSR-DRI topology with opp osite-side routing.
In Ring 1, Nodes 3 and 4 are the interconnect nodes, and in Ring 2, Nodes 8 and 9 are the interconnect
nodes. Duplicate signals are sent from Node 4 (Ring 1) to Node 8 (Ring 2), and between Node 3 (Ring
1) and Node 9 (Ring 2). In Ring 1, traffic at Node 4 is dropped (to Node 9) and continued (to Node 3).
Similarly, at Node 8, traffic is dropped (to Node 3) and continued (to Node 8).
Figure 12-19 ONS 15454 Traditional BLSR Dual-Ring Interconnect (Opposite-Side Routing)
Figure 12-20 shows ONS 15454s in an integrated BLSR-DRI topology. The same drop-and-continue
traffic routing occurs at two nodes, rather than four. This is achieved by installing an additional OC-N
trunk at the two interconnect nodes. Nodes 3 and 8 are the interconnect nodes.
Service Selector
Secondary Path
Primary Path, Drop and Continue to Bridge
Drop and Continue
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BLSR
Ring 1
Primary
Node
Secondary
Node
Node 5
Node 4 Node 3
Node 9 Node 8
Node 1
Node 2
BLSR
Ring 2
Secondary
Node
Primary
Node
Node 10
Node 6
Node 7