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Cisco ONS 15454 Installation and Operations Guide
78-13453-01
Chapter 5 SONET Topologies
Path-Protected Mesh Networks
Be sure to assign the same Ring ID and different node IDs to all nodes in the BLSR. Do not accept the
BLSR ring map until all nodes are provisioned.
Note E-W Mismatch alarms will occur until all nodes are provisioned.
Step 20 Display the network map to view the newly-created ring.
5.6 Path-Protected Mesh Networks
In addition to single BLSRs, UPSRs and ADMs, you can extend ONS 15454 traffic protection by
creating path-protected mesh networks (PPMNs). PPMNs include multiple ONS 15454 SONET
topologies and extend the protection provided by a single UPSR to the meshed architecture of several
interconnecting rings. In a PPMN, circuits travel diverse paths through a network of single or multiple
meshed rings. When you create circuits, you can have CTC automatically route circuits across the
PPMN, or you can manually route them. You can also choose levels of circuit protection. For example,
if you choose full protection, CTC creates an alternate route for the circuit in addition to the main route.
The second route follows a unique path through the network between the source and destination and sets
up a second set of cross-connections.
For example, in Figure 5-39, 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.
If full protection is selected, CTC creates a second unique route between Nodes 3 and 9 which, in this
example, 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 traffic coming in from Node 7 to the
traffic coming in from Node 11 and service resumes. The switch occurs within 50 ms.