Cisco ONS 15600 Reference Manual page 172

8.7 Extended Subnetwork Connection Protection Networks
For example, in
route between the two nodes passes through Node 8 and Node 7, shown by the dotted line, and
automatically creates cross-connections at Nodes 3, 8, 7, and 9 to provide the primary circuit path.
Figure 8-19
Node 1
Node 11
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.
Extended SNCP also allows spans of different SDH line rates to be mixed together in virtual rings.
Figure 8-20
Cisco ONS 15600 SDH Reference Manual, Release 9.0
8-20
Figure 8-19, a circuit is created from Node 3 to Node 9. CTC determines that the shortest
Extended SNCP Network
Node 2
Node 10
Protect traffic
Node 9
shows Nodes 1, 2, 3, and 4 in an STM-64 ring.
Source
Node
Node 3
Node 4
Node 8
Node 7
Destination
Node
Chapter 8 SDH Topologies and Upgrades
Node 5
Node 6
= Primary path
= Secondary path
78-18400-01