Cisco 15454-DS1-14= - 1.544Mbps Expansion Module Reference Manual page 428

12.4.1 BLSR DRI
Figure 12-18
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 between Node 4 (Ring 1) and Node 9 (Ring 2), and between Node 3
(Ring 1) and Node 8 (Ring 2). The primary nodes (Nodes 4 and 9) are on the same side, and the
secondary nodes (Nodes 3 and 8) provide an alternative route. In Ring 1, traffic at Node 4 is dropped (to
Node 9) and continued (to Node 3). Similarly, at Node 9, traffic is dropped (to Node 4) and continued
(to Node 8).
Figure 12-18
Node 10
Cisco ONS 15454 Reference Manual, R8.5
12-20
shows ONS 15454 nodes in a traditional BLSR-DRI topology with same-side routing. In
ONS 15454 Traditional BLSR Dual-Ring Interconnect (Same-Side Routing)
Node 5
Primary
Node
Node 4
Node 9
Primary
Node
Drop and Continue
Service Selector
Primary Path, Drop and Continue to Bridge
Secondary Path
Node 1
BLSR
Ring 1
Secondary
Node
Node 3
Node 8
Secondary
Node
BLSR
Ring 2
Node 6
Chapter 12 SONET Topologies and Upgrades
Node 2
Node 7
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