8. Testing8700-A2-GB20-40 May 2002 8-11Telco-Initiated TestsHotwire 8777 Termination Units support Telco-initiated tests, as shown in thefollowing table.Telco-Initiated Line LoopbackHotwire 8777 Termination Units support line loopback, as specified in AT&TTR 54016, AT&T TR 62411, and ANSI T1.403. A Telco-Initiated Line Loopbackloops the received signal on the DSX-1 interface back to the DSX-1 interfacewithout modification. Framing, CRC, and FDL bits are returned unaltered, and noBPVs or other line coding errors are removed. DSL time slots mapped to theDSX-1 port are sent all ones.Telco-Initiated Payload LoopbackHotwire 8777 Termination Units support payload loopback, as specified in AT&TTR 54016 and ANSI T1.403. A Telco-initiated line loopback loops the receivedsignal on the DSX-1 interface back to the DSX-1 interface. Framing, CRC, andFDL bits are regenerated at the point of the loopback, and BPVs are removed.DSL time slots mapped to the DSX-1 port are sent all ones.Activation andDeactivationLineLoopbackPayloadLoopbackRemote LineLoopbackIn-Band Signal Supported Not Applicable Not SupportedBit-Oriented Supported Supported SupportedMessage-Oriented Not Applicable Not Supported Not ApplicableCAPDSLPort DSX-1PortCAP T1LIUFramerFramerTransceiver99-16252All Ones TelcoCAPDSLPortDSX-1PortCAP T1LIUFramerFramerTransceiver99-16253All Ones Telco
