Cisco Systems 15454 12.5 Linear ADM Configurations, 12.6 Path-Protected Mesh Networks

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Cisco ONS 15454 Reference Manual, R7.0
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Chapter 12 SONET Topologies and Upgrades
12.5 12.5 Linear ADM Configurations
12.5 Linear ADM Configurations
You can configure ONS 15454s as a line of add/drop multiplexers (ADMs) by configuring one set of
OC-N cards as the working path and a second set as the protect path. Unlike rings, point-to-point ADMs
(two-node configurations) and linear ADMs (three-node configurations) require that the OC-N cards at
each node be in 1+1 protection to ensure that a break to the working line is automatically routed to the
protect line.
Figure 12-17 shows three ONS 15454 nodes in a linear ADM configuration. Working traffic flows from
Slot 5/Node 1 to Slot 5/Node 2, and from Slot 12/Node 2 to Slot 12/Node 3. You create the protect path
by placing Slot 6 in 1+1 protection with Slot 5 at Nodes 1 and 2, and Slot 12 in 1+1 protection with
Slot 13 at Nodes 2 and 3.
Figure 12-17 Linear (Point-to-Point) ADM Configuration
12.6 Path-Protected Mesh Networks
In addition to single BLSRs, path protection configurations, 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 path protection 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 12-18 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.
Node 1 Node 3 Node 2
Slot 5 to Slot 5
Slot 6 to Slot 6
Slot 12 to Slot 12
Slot 13 to Slot 13
Working Path
Protect Path
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