Specifications

5-8
Cisco ONS 15454 Installation and Operations Guide, R3.2
March 2002
Chapter 5 SONET Topologies
Bidirectional Line Switched Rings
capacity is the OC-N rate divided by two, multiplied by the number of nodes in the ring minus the
number of pass-through STS-1 circuits. Table 5-3 shows the bidirectional bandwidth capacities of
four-fiber BLSRs.
Figure 5-8 shows an example of BLSR bandwidth reuse. The same STS carries three different traffic sets
simultaneously on different spans on the ring: one set from Node 3 to Node 1, one from Node 1 to Node
2, and another from Node 2 to Node 3.
Figure 5-8 BLSR bandwidth reuse
Table 5-2 Two-Fiber BLSR Capacity
OC Rate Working Bandwidth Protection Bandwidth Ring Capacity
OC-12 STS1-6 STS 7-12 6 x N
1
- PT
2
1. N equals the number of ONS 15454 nodes configured as BLSR nodes.
2. PT equals the number of STS-1 circuits passed through ONS 15454 nodes in the ring (capacity can vary
depending on the traffic pattern).
OC-48 STS 1-24 STS 25-48 24 x N - PT
OC-192 STS 1-96 STS 97-192 96 x N - PT
Table 5-3 Four-Fiber BLSR Capacity
OC Rate Working Bandwidth Protection Bandwidth Ring Capacity
OC-48 STS 1-48 (Fiber 1) STS 1-48 (Fiber 2) 48 x N - PT
OC-192 STS 1-192 (Fiber 1) STS 1-192 (Fiber 2) 192 x N - PT
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