ADTRAN Cable T1 ESF CSU ACE - Manual (Page 39)

Chapter 4. Operation
61202066L1-1B T1 ESF CSU Rackmount User Manual 39
Self-Test
The T1 ESF CSU RM has an extensive set of self-test functions. When
these tests are initiated from the terminal, the T1 ESF CSU RM switches
to the status display where the self-test results are shown. When these tests
are initiated from the DATAMATE, the firmware checksum is displayed
followed by the self-test result. The LEDs on the front of the T1 ESF CSU
RM scroll during self-test.
Local Loopbacks
When the T1 ESF CSU RM is performing a local loop back, it loops the
data received at one of its interfaces back to the transmit data for that
interface. When in line loopback, every bit received at the network
interface is looped back to the network. When in payload loopback, the T1
ESF CSU RM loops back all the data (payload) bits within the Tl stream
and regenerates the framing bits. When in DTE loopback, the T1 ESF
CSU RM loops all the data received at the DTE interface back to the DTE.
The various loopbacks are shown in Figure 4-9 on page 40 through Figure
4-11 on page 41.