Cisco ONS 15454 Reference Manual page 387

Chapter 12 SONET Topologies and Upgrades
Figure 12-4
Node 3
Four-fiber BLSRs provide span and ring switching:
Span switching
•
protect fibers between the nodes (Node 0 and Node 1 in the example in
to the working fibers. Multiple span switches can occur at the same time.
OL-9217-01
Four-Node, Four-Fiber BLSR
Node 0
Span 4
Span 5
OC-48 Ring
Span 6
Span 3
Node 2
(Figure 12-5 on page
Span 1
Span 8
Span 7
Span 2
12-8) occurs when a working span fails. Traffic switches to the
Cisco ONS 15454 Reference Manual, R7.0.1
12.2 12.2.2 Four-Fiber BLSRs
Node 1
= Working fibers
= Protect fibers
Figure 12-5) and then returns
12-7