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Cisco ONS 15600 Reference Manual, R7.2
Chapter 8 SONET Topologies and Upgrades
8.4 Path-Protected Mesh Networks
Figure 8-11 Path-Protected Mesh Network
If full protection is selected, CTC creates a second unique route between Nodes 3 and 9 that passes
through Nodes 2, 1, and 11. Cross-connections are automatically created at Nodes, 3, 2, 1, 11, and 9,
shown by the dashed line. If a failure occurs on the primary path, traffic switches to the second circuit
path. In this example, Node 9 switches from the fiber from Node 7 to the fiber from Node 11 and service
resumes. The switch occurs within 50 ms.
PPMN also allows spans of different SONET line rates to be mixed together in virtual rings. Figure 8-12
shows Nodes 1, 2, 3, and 4 in an OC-192 ring.
= Primary path
= Secondary path
Working traffic
Protect traffic
Source
Node
Destination
Node
78706
Node 1
Node 11
Node 2
Node 4
Node 5
Node 6
Node 7
Node 8Node 10
Node 9
Node 3