ADTRAN Cable T1 ESF CSU ACE User Manual

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T1 ESF CSU ACE User Manual Chapter 3. Operation61204025L1-1B © 2004 ADTRAN, Inc 49Tests are used to control the activation of loopbacks, the initiation of data test patterns, and self testexecution.1)LOCAL LOOPBK, Submenu of 4)TESTFour choices are available for setting the local loopback:NO LOOPBACK Deactivates the loopbackDTE ON Activates the DTE loopbackLINE ON Activates the line loopbackPAYLOAD ON Activates the payload loopbackFigure 3-20. Local Loopback Test Screen2)REM LB, Submenu of 4)TESTActivates the same loopbacks as the LOCAL LOOPBCK but at the far end. This uses either the inbandloop-up code as specified by AT&T 62411 for line loopback (ATT In-Band LLB), or the FDL asspecified in ANSI T1.403 for line loopback codes. An FDL (formerly TABS) maintenance messagecorresponding to AT&T TR54016 can be used for payload loopback as well:NO LOOPBACK Deactivates the loopback.AT&T INBAND LLB Activates the line loopback using inband code.ANSI FDL LLB Initiates the transmission of an FDL line loop-up code toward the far end.AT&T FDL PLB Initiates the transmission of the PLB maintenance messages on the FDL.When a loopback method is selected, the T1 ESF CSU ACE displays LOOPING in the topright corner of the LCD and the yellow LOOPBACK LED is turned on. When the T1 ESFCSU ACE determines that the far-end T1 ESF CSU ACE has looped up, the T1 ESF CSUACE displays LOOPED. If the T1 ESF CSU ACE does not recognize the remote T1 ESFCSU ACE looped up after about 10 seconds, the T1 ESF CSU ACE sends the appropriateloop-down code and displays FAILED, and the LOOPBACK LED is turned off.Excessive errors on the T1 line can cause this failure. The FDL loopbacks fail if the FDLis not intact from one end point to the other. FDL loopbacks are valid only in the ESFframing mode.