5-8
Cisco ONS 15454 Installation and Operations Guide
78-13453-01
Chapter5 SONET Topologies
Bidirectional Line Switched Rings
Figure5-7 BLSR bandwidth reuse
5.2.4 Sample BLSR Application
Figure 5-8 shows a sample two-fiber BLSR implementation. A regional long-dista nce network connects
to other carriers at Node 0. Traffic is delivered to the service providers major hubs.
Carrier 1 delivers six DS-3s over two OC-3 spans to Node 0. Carrier 2 provides twelve DS-3s
directly. Node 0 receives the signals and delivers them around the ring to the appropriate node.
The ring also brings 14 DS-1s back from each remote site to Nod e 0. Intermediate nodes serve these
shorter regional connections.
The ONS 15454 OC-3 card supports a total of four OC-3 ports so that two additional OC-3 spans
can be added at little cost.
STS#1 STS#1
STS#1 STS#1
Node 0
Node 1
Node 2
Node 3
32131
= Node 3 Node 1 traffic
= Node 1 Node 2 traffic
= Node 2 Node 3 traffic