
XRT79L71
PRELIMINARY
263
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
In response to this erred condition, the Transmit E3 Framer (within the Near-End Teriminal) will respond by
setting the "A" bit, within each of its outbound E3 frames to "1" in order to denote a FERF (Far-End Receive
Failure) or RDI (Remote Defect Indicator) condition. Figure 117 presents an illustration of the Transmit E3
Framer sending the FERF/RDI indicator to the Remote Terminal Equipment.
A more detailed discussion on how the Transmit DS3/E3 Framer block and the Receive DS3/E3 Framer block
Using the "A" Bit as the FEBE/REI Bit
The XRT79L71 permits the user to use the "A" bit as a FEBE/REI indicator, provided that the user has also
enabled BIP-4 verification within the E3 frames that it processes. If this feature is invoked, then (in lieu of
carrying the FERF/RDI indicator) the "A" bit will carry the FEBE/REI indicator. In this case, if the Near-End
XRT79L71 detects BIP-4 errors within the incoming (received) E3 data-stream, then it will inform the remote
terminal of this fact by setting the "A" bit-field (within the outgoing, or return E3 frame) to the value "1" in order
FIGURE 116. A SIMPLE ILLUSTRATION OF A NEAR-END TERMINAL DECLARING THE LOS DEFECT CONDITION WITHIN
ITS INCOMING
E3 SIGNAL
FIGURE 117. A SIMPLE ILLUSTRATION OF THE NEAR-END TERMINAL EQUIPMENT TRANSMITTING THE FERF/RDI
INDICATOR TO THE REMOTE TERMINAL EQUIPMENT
Transmit E3
Framer
Receive E3
Framer
Near-End Terminal
Remote
Terminal
Equipment
Remote
Terminal
Equipment
Declares the LOS Defect
Condition
Transmit E3
Framer
Receive E3
Framer
Near-End Terminal
Remote
Terminal
Equipment
Remote
Terminal
Equipment
1
A Bit
Declares the LOS Defect
Condition