Cisco ONS 15454 DWDM, Installation And Operation Manual

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Cisco ONS 15454 DWDM Installation and Operations Guide, R6.0
August 2005
Chapter 18 Network Reference
18.8 Network-Level Gain—Tilt Management of Optical Amplifiers
8. Node A power monitoring photodiode detects a LOS-P on the OSC-CSM card. Refer to the Cisco
ONS 15454 Troubleshooting Guide or the Cisco ONS 15454 SDH Troubleshooting Guide .
9.
On the OSC-CSM, the simultaneous LOS-O and LOS-P detection triggers a change in the position
of the optical switch. CTC reports a LOS alarm (loss of continuity), while LOS-O and LOS-P are
demoted. Refer to the
Cisco ONS 15454 Troubleshooting Guide or the Cisco ONS 15454 SDH
Troubleshooting Guide .
10.
The OSC laser is shut down.
11.
The optical switch blocks outgoing traffic.
When the fiber is repaired, either an automatic or manual restart at the Node A OSC-CSM OSC or at the
Node B OSC-CSM OSC is required. A system that has been shut down is reactivated through the use of
a restart pulse. The pulse is used to signal that the optical path has been restored and transmission can
begin. For example, when the far-end Node B receives a pulse, it signals to the Node B OSC to begin
transmitting its optical signal and for the optical switch to pass incoming traffic. The OSC-CSM at Node
A then receives the signal and tells the Node A OSC to resume transmitting and for the optical switch to
pass incoming traffic.
18.8 Network-Level Gain—Tilt Management of Optical
Amplifiers
The ability to control and adjust per channel optical power equalization is a principal feature of
ONS 15454 DWDM Metro-Core network applications. A critical parameter to assure optical spectrum
equalization throughout the DWDM system is the gain flatness of EDFA amplifiers.
Two items, gain tilt and gain ripple, are factors in the power equalization of optical amplifier cards such
as the OPT-BST/OPT-BST-E or OPT-PRE.
Figure 18-13 is a graph of the amplifier output power
spectrum and how it is affected by gain tilt and gain ripple.