XRT79L71
PRELIMINARY
429
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
Next, Figure 202 presents an illustration of a given Near-End Terminal that is detecting an EM byte error within
its incoming E3 signal. More specifically, the Receive E3 Framer block has locally computed an EM byte value
of "0x5B" that was computed over a given incoming E3 frame. Figure 202 indicates that the EM byte value
which resides within the very next incoming E3 frame is of the value "0x5A". As a consequence, an EM byte
error is being detected at this time.
In response to this erred condition, the Transmit E3 Framer within the Near-End Terminal will respond by
setting the FEBE/REI bit, within the very next outbound E3 frame to the value "1" in order to denote a FEBE/
REI event. More specifically, the Transmit E3 Framer within the Near-End Terminal will transmit an E3 frame
with the FEBE/REI bit set to "1" each time the corresponding Receive E3 Framer within the Near-End Terminal
detects an EM byte errors within an E3 frame. Figure 203 presents an illustration of the Transmit E3 Framer
sending the FEBE/REI 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
Bits 3 through 5 - Payload Type[2:0]
FIGURE 202. A SIMPLE ILLUSTRATION OF A NEAR-END TERMINAL DETECTING EM BYTE ERRORS WITHIN ITS INCOM-
ING
E3 SIGNAL
FIGURE 203. A SIMPLE ILLUSTRATION OF THE NEAR-END TERMINAL EQUIPMENT TRANSMITTING THE FEBE/REI
INDICATOR TO THE REMOTE TERMINAL EQUIPMENT
Transmit E3
Framer
Receive E3
Framer
Near-End Terminal
Remote
Terminal
Equipment
Remote
Terminal
Equipment
EM Byte
Locally Calculated
EM Byte
0x5A
0x5B
Transmit E3
Framer
Receive E3
Framer
Near-End Terminal
Remote
Terminal
Equipment
Remote
Terminal
Equipment
MA Byte
x1xxxxxx
FEBE bit