Cisco ONS 15454 DWDM - Figure 10-16 Nodes Using OPT-BST-L Cards; Scenario 3: Fiber Cut in Nodes Using OPT-BST-L Cards

10-24
Cisco ONS 15454 DWDM Reference Manual, R8.5
78-18343-02
Chapter 10 Network Reference
10.7.3 Fiber Cut Scenarios
8. 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 DWDM Troubleshooting Guide.
9. The OSC laser is shut down.
10. The optical switch blocks outgoing traffic.
When the fiber is repaired, either an automatic or manual restart at the Node A OSC-CSM card OSC or
at the Node B OSC-CSM card OSC is required. A system that has been shut down is reactivated through
the use of a restart pulse. The pulse indicates the optical path is 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.
10.7.3.3 Scenario 3: Fiber Cut in Nodes Using OPT-BST-L Cards
Figure 10-16 shows nodes using OPT-BST-L cards with a fiber cut between them.
Figure 10-16 Nodes Using OPT-BST-L Cards
Two photodiodes at Node B monitor the received signal strength for the optical payload and OSC signals.
When the fiber is cut, an LOS is detected at both of the photodiodes. The AND function then indicates
an overall LOS condition, which causes the OPT-BST-L transmitter and OSCM lasers to shut down. This
OPT-BST-L OPT-BST-L
P
P
P
OSCM
PP
OSCM
= power monitoring photodiode
= logical AND function
Node A
Side B
Node B
Side A
X
11
1
7
13
10
9 8
12
6
2 3
4
5
2
8
145950
OPT-AMP-L
OPT-AMP-L