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Chapter 7. Test Menu
Network Tests
Loopback Tests
Network Interface Loopbacks
58
Network tests are used to control the activation of loopbacks
and the initiation of data test patterns.
The network tests are run on the network interface (NI). Three
different test configurations can be selected to determine the
type of loopback and the pattern to run. Test results are
displayed in the LCD window. See Figure 7-2.
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
loopdown codes). Additionally, the loopbacks can be remotely
controlled by means of out-of-band commands by the E1 ESF
FDL or from T-Watch PRO via a modem connection.
Network interface loopbacks affect the entire E1 data stream
(see Figure 7-3 on page 59). The two types of network loop-
backs are described below.
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
Similar to line loopback, except that the framing is extracted
from the received data and then regenerated for the
transmitted data.
Figure 7-2. Local Loopback Screen
ESU LT User Manual
61200410L1-1B
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