VSC6134
Datasheet
2.15.8
FEC to Legacy FEC with Synchronously Mapped Payload Modes
There are two synchronously mapped payload FEC to legacy FEC modes:
●
●
StFEC(S) <-Transparent/SONET-> LFEC(NS), 238/237
StFEC(NS) <-Transparent/SONET-> LFEC(S), 237/238
The following figure shows the FEC to Legacy FEC Bridge mode with synchronously mapped payload.
SONET is monitored and may be optionally regenerated. In the add direction, the StFEC signal is
framed, decoded, and optionally corrected; DWOH monitoring is performed; and the DWOH is
terminated (DWOH cannot be passed through). The synchronously mapped SONET signal is monitored
and optionally regenerated. New DWOH is then inserted, and the LFEC parity bytes are recalculated
and added.
In the drop direction the LFEC signal is framed, decoded, and optionally corrected; DWOH monitoring
is performed; and the DWOH is terminated (DWOH cannot be passed through). The synchronously
mapped SONET payload is monitored and optionally regenerated, new DWOH is then inserted, and the
StFEC parity bytes are recalculated and added.
The StFEC(S) to LFEC(NS) mode supports extraction of the OTU stuff bytes in the add direction and
insertion of the OTU stuff bytes in the drop direction. The StFEC(NS) to LFEC(S) mode supports the
insertion of the OTU stuff bytes in the add direction and the extraction of the OTU stuff bytes in the
drop direction.
Figure 42. FEC from/to Legacy FEC Bridge with SONET Regeneration Mode
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VMDS-10185 Revision 4.0
July 2006
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
