Cisco ONS 15600 Reference Manual page 138

8.3.2 Four-Fiber BLSRs
Figure 8-5
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.
Cisco ONS 15600 Reference Manual, R6.0
8-6
Four-Node, Four-Fiber BLSR
Node 0
Span 4
Span 5
OC-48 Ring
Span 6
Span 3
Node 2
(Figure 8-6 on page
Chapter 8
Span 1
Span 8
Span 7
Span 2
8-7) occurs when a working span fails. Traffic switches to the
SONET Topologies and Upgrades
Node 1
= Working fibers
= Protect fibers
Figure 8-6) and then returns