Cisco ONS 15454 DWDM - Page 159

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Cisco ONS 15454 DWDM Reference Manual, R8.5
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Chapter 3 Optical Service Channel Cards
3.4 OSC-CSM Card
• Automatic laser shutdown (ALS), a safety mechanism used in the event of a fiber cut. For details on
ALS provisioning for the card, see the Cisco ONS 15454 DWDM Procedure Guide. For information
on using the card to implement ALS in a network, see the “10.7 Network Optical Safety” section
on page 10-18.
The WDM signal coming from the line is passed through the OSC combiner and separator, where the
OSC signal is extracted from the WDM signal. The WDM signal is sent along with the remaining
channels to the COM port (label on the front panel) for routing to the OADM or amplifier units, while
the OSC signal is sent to an optical transceiver.
The OSC is an OC-3/STM-1 formatted signal. The OC-3/STM-1 SDCC or RS-DCC overhead bytes are
used for network communications. An optical transceiver terminates the OC-3/STM-1, and then it is
regenerated and converted into an electrical signal. The SDCC or RS-DCC bytes are forwarded to the
active and standby TCC2/TCC2P cards for processing via the SCL bus on the backplane. Orderwire
bytes (E1, E2, F1) are also forwarded via the SCL bus to the TCC2/TCC2P for forwarding to the AIC-I
card.
The payload portion of the OC-3/STM-1 is used to carry the fast Ethernet UC. The frame is sent to a
POS processing block that extracts the Ethernet packets and makes them available at the RJ-45 front
panel connector.
The OSC-CSM distributes the reference clock information by removing it from the incoming
OC-3/STM-1 signal and then sending it to the active and standby TCC2/TCC2P cards. The clock
distribution is different from the OSCM card because the OSC-CSM does not use Slot 8 or 10
(cross-connect card slots).
Note S1 and S2 (Figure 3-10 on page 3-12) are optical splitters with a splitter ratio of 2:98. The result is that
the power at the MON TX port is about 17 dB lower than the relevant power at the COM RX port, and
the power at the MON RX port is about 20 dB lower than the power at the COM TX port. The difference
is due to the presence of a tap coupler for the P1 photodiode.