ADTRAN FNID Installation And Maintenance Manual

Also see for T200 FNID: Installation and maintenance practice Quick start guide Installation and Maintenance Installation and Maintenance Installation and maintenance practice

Contents

ADTRAN FNID Installation And Maintenance Manual Manual pdf 16 page image

A-3Section 61245201L1-5, Issue 361245201L1-5C3. LOOPBACK ACTIVATION/DEACTIVATIONThis section describes loopback activation anddeactivation methods for the ADTRAN Fractional T1system. Loopback activation and deactivation iscontrolled with the push-button located on the frontpanel, through craft interface, or latching loopbackcodes.Both the FNID and the FT1 DP have a push-buttonlocated on the front panel labeled REM LBK or RLBwhich controls the activation of remote loopback.Pressing REM LBK or RLBon the FNID activatesFT1 DP CPE loopback. Pressing REM LBK or RLBon the FT1 DP activates FNID network loopback orrepeater loopback when a repeater is present. Remoteloopback is deactivated by pressing the REM LBK orRLB or waiting for the 20-minute loopback timeout, ifenabled.The FNID and FT1 DP (when available) have a craftinterface located on the front panel of the device. Thecraft interface allows access to the FT1 device throughan RS-232-type interface. All loopbacks for the FNIDand FT1 DP can be controlled from the craft interface.The craft interface on the FNID can activate anddeactivate the FNID network loopback and the FNIDCPE loopback. The FNID craft interface can alsoremotely activate and deactivate the FT1 DP networkloopback, FT1 DP CPE loopback, and the repeaternetwork loopback. The craft interface on the FT1 DPcan activate and deactivate the FT1 DP networkloopback and the FT1 DP CPE loopback. The FT1DP craft interface can also remotely activate anddeactivate the FNID network loopback and the FNIDCPE loopback and the repeater network loopback.FT1 DP, FT1 Repeater, and FNID network loopbackscan be activated by the DDS latching loopbacksequence. The latching loopback sequence is detectedin the primary DS0 of the FT1 system. When theloopback is activated on the device, thewhole FT1 bandwidth is looped. TheFT1 DP, FT1 Repeater, and FNID eachrespond to a different loopback selectcode allowing for sectionalization of thenetwork during testing. Table A-1 is alist of FT1 devices and their loopbackselect codes.Latching loopbacks for the FT1 system are activatedby transmitting the following latching loopbacksequence in the primary DS0 of the FT1 system:A. Minimum of 35 transition in progress (TIP) bytes(N0111010).B. Minimum of 35 loopback select code (LSC) bytes asdefined in Table I.C. Minimum of 100 loopback enable (LBE) bytes(N1010110).D. Minimum of 35 all 1s bytes (S1111111), plus aminimum of 100 LBE bytes. (N-1) iterations, whereN is the number of channel units of the same type(i.e., same LSC) that lie between the test center andthe loopback to be operated. This step is only usedwhen there are identical channel units in tandem.E. Minimum of 32 far end voice (FEV) bytes(N1011010).A 25-second watchdog timer is activated between the35 TIP bytes and 35 LSC bytes, between the 35 LSCbytes and 100 LBE bytes, and between the 100 LBEbytes and 32 FEV bytes. The timer requires thecorrect receipt of the latter sequences less than 25seconds after receipt of the prior sequence. Thisprevents inadvertent setting of the latching loopbacks.Latching loopbacks for the FT1 system aredeactivated by transmitting the following latchingloopback sequence in the primary DS0 of the FT1system:Minimum of 35 TIP bytes (N0111010).4. LOOPUP STATEIn the loopup state, the active FT1 loopback willprovide a continuous loop for the FT1 bandwidth.The data flow is continuously monitored for the loopdeactivation commands to deactivate the loopbacks.Also, a 20-minute loopback timeout is checked. If theloopback timeout is enabled, any loopback that is inthe loopup state for 20 minutes will be deactivated.Table A-1. FT1 Loopback Select CodesFT1 Device Loopback Select Loopback SelectCode Name Code ByteFT1 DP ................................. OCU loopback .............................. N1010101FT1 Repeater #1 ................... NEI Position 1 loopback .............. N1000001FT1 Repeater #2 ................... NEI Position 2 loopback .............. N1000001FNID without repeater ......... NEI Position 1 loopback .............. N1000001FNID with one repeater ....... NEI Position 2 loopback .............. N1000001FNID with two repeaters ..... NEI Position 3 loopback .............. N1000001

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