8-7
Cisco ONS 15600 Reference Manual, R7.2
Chapter 8 SONET Topologies and Upgrades
8.3.2 Four-Fiber BLSRs
Figure 8-6 Four-Fiber BLSR Span Switch
Ring switching (Figure 8-7) occurs when a span swi tch cannot recover traffic, such as when both
the working and protect fibers fail on the same span. In a ring switch, traffic is routed to the protect
fibers throughout the full ring.
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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