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Loopback Diagnostics

Loop Back Configure/Query message

The Loop Back Configure/Query message can help to determine whether the cause of a problem is inside or outside of the CSP. The message works by looping signals from the E-ONE, T-ONE, and DS3 cards back to the network. To enable remote loopback, first take the span you want to use out of service. In the Loop Back Configure/Query message, specify a logical span ID and set the action flag to enable loop back.

The E-ONE and T-ONE cards also include card diagnostics for carrier group alarm detection and generation, loss of frame and signal detection, and loop timing support. The host uses the Span Status Query message to retrieve the following statistics:

• Bipolar/Code violations

• Excessive zeroes

• Slips

• Cyclic Redundancy Check (CRC) errors

• Out Of Frame (OOF) defects

• Alarm Indication Signal (AIS) defects

Range of channels provided by T1 or E1 transmission service. A physical span is a group of channels taking up a single physical wire. A logical span is a group of channels taking up less than a single logical wire, or carried over more than one physical wire.
A group of data bits in a specific format, with a flag at each end to indicate the beginning and the end of the frame.