Troubleshooting guide

MX2820 System Manual
5-92 61186003L1-1D
DS3 LOOPBACKS
Performing a loopback test for the DS3 network requires selecting option 29 from the
Loopbacks menu screen. Figure 5-60 shows an example for the DS3 Loopbacks menu screen.
Selecting option 1,
DATA MODE, ends a test in progress.
Figure 5-60. DS3 Loopbacks Menu
Line Loopback
The DS3 Line Loopback test performs a loop of the DS3 signal back to the network. This
loopback occurs prior to the DS3 framer and B3ZS decoder, but makes full use of the DS3 LIU
in both receive and transmit directions. Therefore, any coding violations received by the DS3
LIU are inserted back into the network without modification. Figure 5-61 provides an illus-
tration of this test.
NOTE
If a DS3 Line Loopback test is active when the M13 MUX is operat-
ing in the local timing mode, the timing source for the DS3 equip-
ment is effectively removed from the circuit. Therefore, it is up to
the test equipment or network to provide DS3 timing into the cir
-
cuit for the duration of the test.
Shelf: 1 Slot: 4A ADTRAN MX2820 System 04/13/04 16:49
Unacknowledged Alarms: None TID: HTVLALEXD16
DS3 Loopbacks
DS3: Data Mode
1 - Data Mode
2 - Line Loopback
3 - Digital Loopback
4 - Remote Loopback
5 - Remote ALL T1/E1
Selection: '?' - System Help Screen