ADTRAN TOTAL ACCESS MX2800, Руководство пользователя, Страница: 91 / 142

Chapter 6. Diagnostics
61200290L1-1 MX2800 User Manual 6-7
DS3 LOOPBACKS
After you select DS3 L
OOPBACK
, the menu in Figure 6-8 appears.
The sections following the figure provide descriptions and
illustrations of the testing options. Select
1=D
ATA
M
ODE
to end a
test in progress.
Figure 6-8. DS3 Diagnostics Menu
Line Loopback
L
INE
L
OOPBACK
performs a loop of the DS3 back to the network.
This loopback occurs just prior to the DS3 framer and B3ZS
decoder, but it makes full use of the DS3 LIU in both receive and
transmit directions; therefore, any coding violations received by the
DS3 will be inserted back into the network without modification.
See Figure 6-9 on page 6-8 for an illustration of this test.
If a L
INE
loopback is active when the MX2800 is operating in the L
OCAL
timing mode, the timing source for the DS3 is effectively removed from
the circuit. Therefore, it is up to the test equipment or network to provide
DS3 timing into the circuit for the duration of the test.