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Cisco ONS 15600 SDH Reference Manual, Release 9.0
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Chapter 8 SDH Topologies and Upgrades
8.7 Extended Subnetwork Connection Protection Networks
For example, in
, a circuit is created from Node 3 to Node 9. CTC determines that the shortest
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
Extended SNCP 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.
Extended SNCP also allows spans of different SDH line rates to be mixed together in virtual rings.
shows Nodes 1, 2, 3, and 4 in an STM-64 ring.
= Primary path
= Secondary path
Wo
rking tr
affic
Protect traffic
Source
Node
Destination
Node
78706
Node 1
Node 11
Node 2
Node 4
Node 5
Node 6
Node 7
Node 8
Node 10
Node 9
Node 3