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ADCP-61-471 • Issue 4 • June 2000 • Section 2: Operation and Maintenance

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© 2000, ADC Telecommunications, Inc.

The HDSL loopback process is similar to other T1 intelligent repeater methods. For

Version D and later HLX modules, the HLXC loopback is like an intelligent office repeater
loopback. The HLXR loopback and HRX loopback are like an intelligent inline T1 repeater
loopback.

The HDSL loopback operation is described by the diagram in 

Figure 102-1

. The four states are:

• Disarmed

• Armed

• Loopup

• Loopup/Time-Out Disable

7077-C

Inband and ESF data link sequences and time-out operations produce the state transitions. These
sequences and time-out values are:

• Arming sequence (inband or ESF data link)

• Activation sequence

• Deactivation sequence

• Disarming sequence (inband or ESF data link)

• Loopup time-out

• Arming time-out