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XRT72L53
THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
PRELIMINARY
REV. P1.1.6
422
However, if the locally computed BIP-8 value does not
match the EM byte of the corresponding E3 frame,
then the Receive E3 Framer block will do the follow-
ing.
It will inform the Remote Terminal of this fact by
having the Local Transmit E3 Framer block send
the Remote Terminal an E3 frame, with the FEBE
bit-field, within the MA byte, set to “1”. This phe-
nomenon is illustrated below in Figure 198 and
Figure 199.
Figure 198 illustrates the Local Receive E3 Framer
receiving an errored E3 frame. In this figure, the Lo-
cal Receive E3 Frame block is receiving an E3 frame
with an EM byte containing the value “0x5A”. This
value does not match the locally computed EM byte
value of “0x5B”. Consequently, there is an error in
this E3 frame.
Figure 199 illustrates the subsequent action of the
Local Transmit E3 Framer block, which will transmit
an E3 frame, with the FEBE bit-field set to “1” to the
Remote Terminal. This signaling indicates that the
Local Receive E3 Framer block has received an er-
rored E3 frame.
F
IGURE
198. I
LLUSTRATION
OF
THE
L
OCAL
R
ECEIVE
E3 F
RAMER
BLOCK
,
RECEIVING
AN
E3 F
RAME
(
FROM
THE
R
EMOTE
T
ERMINAL
)
WITH
AN
INCORRECT
EM B
YTE
.
Transmit E3
Framer
Receive E3
Framer
Local Terminal
Remote
Terminal
EM Byte
Locally Calculated
EM Byte
0x5A
0x5B