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Cisco ONS 15600 SDH Reference Manual, Release 9.0
78-18400-01
Chapter 8 SDH Topologies and Upgrades
8.3.1 Two-Fiber MS-SPRings
Figure 8-3
Four-Node, Two-Fiber MS-SPRing Traffic Pattern Sample
shows how traffic is rerouted following a line break between Node 0 and Node 3.
•
All circuits originating on Node 0 that carried traffic to Node 2 on Fiber 2 are switched to the protect
bandwidth of Fiber 1. For example, a circuit carried on VC4-1 on Fiber 2 is switched to VC4-9 on
Fiber 1. A circuit carried on VC4-2 on Fiber 2 is switched to VC4-10 on Fiber 1. Fiber 1 carries the
circuit to Node 3 (the original routing destination). Node 3 switches the circuit back to VC4-1 on
Fiber 2 where it is routed to Node 2 on VC4-1.
•
Circuits originating on Node 2 that normally carry traffic to Node 0 on Fiber 1 switch to the protect
bandwidth of Fiber 2 at Node 3. For example, a circuit carried on VC4-2 on Fiber 1 is switched to
VC4-10 on Fiber 2. Fiber 2 carries the circuit to Node 0 where the circuit is switched back to VC4-2
on Fiber 1 and then dropped to its destination.
Node 0
Node 1
Traffic flow
Node 2
Node 3
STM-16 Ring
Fiber 1
Fiber 2
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