XRT7250 datasheet(319/463 Pages) EXAR

319 / 463 page

XRT7250

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DS3/E3 FRAMER IC

REV. 1.1.1

300

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 Lo-

cal 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.

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”

Transmit E3

Framer

Receive E3

Framer

Local Terminal

Remote

Terminal

A Bit

Value = 0

XRT7250 Datasheet(PDF) 319 Page - Exar Corporation