ADTRAN SLC-5 U-BR1TE III User Manual download pdf (Page 87)

Chapter 7. Test Menu

61202052L1-1 TSU 100 User Manual

7-3

Loopback Tests

A number of different loop-backs can be invoked locally from

the front panel, by T-WATCH Pro commands, or remotely by

using special in-band codes (AT&T D4 network loop-up and

loop-down codes). Additionally, the loop-backs can be

remotely controlled 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 loop-backs affect the entire T1 data stream.

See Figure 7-2. There are two types of network loop-backs, line

loop-back and payload loop-back.

Line loop-back

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 loop-back

Similar to line loop-back, except that the framing is extracted

from the received data and then regenerated for the transmit-

ted data.

Figure 7-2. Network Loopback Tests

TSU 100

DS1

NI CSU

Payload Loopback

Line Loopback

Secondary

Interface

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ADTRAN SLC-5 U-BR1TE III User Manual Page 87