XRT72L53 Datasheet, PDF (318/467 Pages) Exar Corporation – THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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PRELIMINARY
XRT72L53
THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.8
FIGURE 139. ILLUSTRATION OF THE LOCAL RECEIVE E3 FRAMER BLOCK, TRANSMITTING AN E3 FRAME (TO THE
REMOTE TERMINAL) WITH THE “A” BIT SET TO “0”
Local Terminal
Value = 0
Transmit E3
Framer
Receive E3
Framer
A Bit
Remote
Terminal
However, if the locally computed BIP-4 value does not
match the BIP-4 value 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 “A” bit-
field set to “1”. This phenomenon is illustrated
below in Figure 140 and Figure 141.
Figure 140 illustrates the Local Receive E3 Framer
receiving an errored E3 frame. In this figure, the Local
Receive E3 Frame block is receiving an E3 frame with
an BIP-4 containing the value “0xA”. This value does
not match the locally computed BIP-4 value of “0xB”.
Consequently, there is an error in the previous E3
frame.
Figure 141 illustrates the subsequent action of the
Local Transmit E3 Framer block, which will transmit
an E3 frame, with the A bit-field set to “1” to the Re-
mote Terminal. This signaling indicates that the Local
Receive E3 Framer block has received an errored E3
frame.
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