ADTRAN TSU 120e - Manual (Page 91)

Chapter 7. Test Menu
61202129L1-1 TSU 120 User Manual 7-3
Network Tests
Network tests control the activation of loopbacks and the initia-
tion of data test patterns.
Network tests are run on the Network Interface (NI). You can
select three different test configurations to determine the type
of loopback and the pattern to run. Test results display in the
LCD window.
Executing N ETWORK T ESTS will disrupt normal data flow
unless only TST DS0S are selected for testing.
Loopback Tests
A number of different loopbacks can be invoked locally from
the front panel, by T-Watch commands, or remotely by using
special in-band codes (AT&T D4 network loop-up and loop-
down codes). Additionally, the loopbacks can be remotely con-
trolled by means of out-of-band commands by the
T1 ESF FDL
or from T-WATCH Pro by a modem connection.
Network Interface Loopbacks
Network interface loopbacks (see Figure 7-2 on page 7-4) affect
the entire T1 data stream. There are two types of network loop-
backs,
LINE LOOPBACK and PAYLOAD LOOPBACK .
Line Loopback
Line loopback 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 Loopback
Payload loopback is similar to line loopback, except that the
framing is extracted from the received data and then regener-
ated for the transmitted data.