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Chapter 7 Test Menu TSU LT User Manual
50 © 2003 ADTRAN, Inc. 61203060L1-1A
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AYLOAD
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. Figure 7-2 shows an illustration of how the tests work.
Figure 7-2. Network Loopback Tests
Remote Loopback
Activates loopback tests at the far end.
No Loopback Deactivates the loopback.
Line On
Activates the line loopback which loops all of the received data back toward the
network. The transmitted data is the identical line code that was received, including
any bipolar violations or framing errors.
Payload On Activates the payload loopback which is similar to line loopback, except that the
framing is extracted from the received data and then regenerated for the transmitted
data.
No Loopback Deactivates the loopback.
V.54 Inband PLB
Indicates inband transmission of V.54 loop-up pattern in channels occupied by
DTE data only. This choice should be used for public fractional network.
ANSI FDL LLB
Per ANSI T1.403, initiates the transmission of a Facility Data Link (FDL) line
loop-up code toward the far end using the following 2-byte bit patterns:
00001110 11111111.
AT&T Inband LLB Per AT&T 62411, activates the line loopback using inband code.
ANSI FDL PLB
Per ANSI T1.403, activates the payload loopback (PLB) on the FDL using the
following 2-byte bit patterns: 00010100 11111111.
AT&T FDL PLB
Per AT&T TR54016
,
initiates the transmission of the PLB on the FDL using a
request message.
Only V.54 loopbacks can be used with fractional T1 since the full T1 stream including the
FDL is not transported to the far end (unless it is a private network).
Facility Data Link (FDL) specifically relates to ESF.