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Cisco ONS 15454 Reference Manual, R7.0
78-17191-01
Chapter 12 SONET Topologies and Upgrades
12.2 12.2.2 Four-Fiber BLSRs
Figure 12-4 Four-Node, Four-Fiber BLSR
Four-fiber BLSRs provide span and ring switching:
Span switching (Figure 12-5 on page 12-7) occurs when a working span fails. Traffic switches to the
protect fibers between the nodes (Node 0 and Node 1 in the example in Figure 12-5) and then returns
to the working fibers. Multiple span switches can occur at the same time.
Node 0
Node 1
Node 2
Node 3
Span 1
Span 2Span 3
Span 4
Span 8
Span 7Span 6
Span 5
OC-48 Ring
= Working fibers
= Protect fibers
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