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Cisco ONS 15600 SDH Reference Manual, Release 9.0
78-18400-01
Chapter 7 Circuits and Tunnels
7.10.2 Secondary Sources and Destination
7.10.2 Secondary Sources and Destination
CTC supports secondary sources and destinations (drops). Secondary sources and destinations typically
interconnect two third-party networks, as shown in
. Traffic is protected while it traverses a
network of ONS 15600 SDHs.
Figure 7-5
Secondary Sources and Drops
Several rules apply to secondary sources and destinations:
•
CTC does not allow a secondary destination for unidirectional circuits because you can specify
additional destinations after you create the circuit.
•
Primary and secondary sources should be on the same node.
•
Primary and secondary destinations should be on the same node.
•
Secondary sources and destinations are permitted only for regular VC4 connections.
For bidirectional circuits, CTC creates an SNCP connection at the source node that allows traffic to be
selected from one of the two sources on the ONS 15600 SDH network. If you check the Fully Path
Protected option during circuit creation, traffic is protected within the ONS 15600 SDH network. At the
destination, another SNCP connection is created to bridge traffic from the ONS 15600 SDH network to
the two destinations. A similar but opposite path exists for the reverse traffic flowing from the
destinations to the sources.
For unidirectional circuits, an SNCP drop-and-continue connection is created at the source node.
Note
Automatic routing and its associated subfields are not available if both the Automatic Circuit Routing
NE default and the Network Circuit Automatic Routing Overridable NE default are set to FALSE. For a
full description of these defaults see
Appendix C, “Network Element Defaults.”
7.11 Manual Circuit Routing
Routing circuits manually allows you to:
•
Choose a specific path, not just the shortest path chosen by automatic routing.
•
Choose a specific VC4 on each link along the route.
159618
Primary source
Secondary source
Primary destination
Secondary destination
Vendor A
network
Vendor B
network
ONS 15600 SDH network
