Specifications

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Cisco ONS 15530 Planning Guide
OL-7708-01
Chapter 2 Protection Schemes and Network Topologies
Trunk Fiber Based Protection
Trunk Fiber Based Protection
The PSM (protection switch module) provides trunk fiber based protection on Cisco ONS 15530
systems configured in point-to-point topologies. This type of protection only provides protection against
trunk fiber cuts, not specific channel failure as provided by splitter and line card based schemes.
However, this protection scheme allows for much simpler shelf configurations in topologies where per
channel protection is not required.
Figure 2-12 shows trunk fiber based protection configured with a transponder line card and an OADM
module.
Figure 2-12 Trunk Fiber Based Protection With a Transponder Line Card
Trunk Fiber Based Protection Considerations
The following considerations apply when using trunk fiber based protection:
• Trunk fiber based protection does not protect against failures on the shelf itself or the client
equipment. To protect against these failures, line card protection should be implemented on the
client equipment itself.
• Due to the cumulative effect of the noise from the EDFAs (erbium-doped fiber amplifiers), the PSM
cannot support point-to-point topologies with more than two EDFAs on the trunk fiber. For
topologies with three or more EDFAs on the trunk fiber, use splitter based protection.
• When EDFAs are present in the topology, the power of the data channels at the PSM receiver must
be greater than the cumulative noise of the EDFAs.
• The APS software that supports trunk fiber based protection can be configured as revertive or
nonrevertive. After a switchover, the active traffic can be put back on the previously failed working
fiber, once the fault has been remedied, either automatically (revertive) or through manual
intervention (nonrevertive).
line card
OADM
module
West
East
Client optics ITU optics
Performance
monitor
CPU
LRC
OSC
Redundant
CPU switch
modules
Active Signal
Electrical
backplane
connection
PSM
Standby Signal
Optical fiber
connection
Client
device
SRC
LRC
2.5-Gbps transponder
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