8-40
Cisco ONS 15454 DWDM Reference Manual, R8.5
78-18343-02
Chapter 8 Transponder and Muxponder Cards
8.8.8 FEC and E-FEC Modes
• E-FEC—Standard ITU-T G.975.1 I.7, two orthogonally concatenated BCH super FEC code. This
FEC scheme contains three parameterizations of the same scheme of two orthogonally interleaved
block codes (BCH). The constructed code is decoded iteratively to achieve the expected
performance.
8.8.8 FEC and E-FEC Modes
As client side traffic passes through the card, it can be digitally wrapped using FEC mode error
correction or E-FEC mode error correction (or no error correction at all). The FEC mode setting provides
a lower level of error detection and correction than the E-FEC mode setting of the card. As a result, using
E-FEC mode allows higher sensitivity (lower OSNR) with a lower BER than FEC mode. E-FEC enables
longer distance trunk-side transmission than with FEC.
The E-FEC feature is one of three basic modes of FEC operation. FEC can be turned off, FEC can be
turned on, or E-FEC can be turned on to provide greater range and lower BER. The default mode is FEC
on and E-FEC off. E-FEC is provisioned using CTC.
8.8.9 SONET/SDH Overhead Byte Processing
The card passes the incoming SONET/SDH data stream and its overhead bytes for the client signal
transparently. The card can be provisioned to terminate regenerator section overhead. This is used to
eliminate forwarding of unneeded layer overhead. It can help reduce the number of alarms and help
isolate faults in the network.
8.8.10 Client Interface Monitoring
The following parameters are monitored on the MXP_2.5G_10E_C and MXP_2.5G_10E_L cards:
• Laser bias current is measured as a PM parameter.
• LOS is detected and signaled.
• Rx and Tx power are monitored.
The following parameters are monitored in real time mode (one second):
• Optical power transmitted (client)
• Optical power received (client)
In case of LOC at the DWDM receiver or far-end LOS, the client interface behavior is configurable. AIS
can be invoked or the client signal can be squelched.
8.8.11 Wavelength Identification
The card uses trunk lasers that are wavelocked, which allows the trunk transmitter to operate on the ITU
grid effectively. Both the MXP_2.5G_10E_C and MXP_2.5G_10E_L cards implement the UT2 module.
The MXP_2.5G_10E_C card uses a C-band version of the UT2 and the MXP_2.5G_10E_L card uses an
L-band version.
Table 8-18 describes the required trunk transmit laser wavelengths for the MXP_2.5G_10E_C card. The
laser is tunable over 82 wavelengths in the C band at 50-GHz spacing on the ITU grid.
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