118 CHAPTER 4: WAN INTERFACE CONFIGURATIONStarting/Stopping aBERT Test on T1-FInterfaceBERT is operating as follows:The local end sends out a pattern, which is to be looped over somewhere on theline and back to the local end. The local end then checks the received pattern forthe bit error rate, and by so doing helps you determine whether the condition ofthe line is good. To this end, you must configure loopback to allow the transmittedpattern to loop back from somewhere on the line, for example, from the far-endinterface by placing the interface in far-end loopback.You may view the state and result of the BERT test with the display ft1 serialcommand.Set the behavior of theinterface on the FDL in ESFframingft1 fdl { ansi | att | both |none }OptionalFDL is disabled by default.Set the CRC mode crc { 16 | 32 | none } Optional16-bit CRC by default.Set the frame format ft1 frame-format { esf | sf } OptionalThe default is esf.Set alarm thresholds ft1 alarm-threshold lospulse-detection valueft1 alarm-threshold lospulse-recovery valueft1 alarm-threshold ais{ level-1 | level-2 }ft1 alarm-threshold lfa{ level-1 | level-2 | level-3 |level-4 }OptionalFor LOS alarmThe threshold ofpulse-detection defaults to176 and the threshold ofpulse-recovery defaults to 22.That is, if the number of thepulses detected during thetotal length of 176 pulsedetection intervals is smallerthan 22, the pulse-recoverythreshold, a LOS alarm occurs.Both AIS alarm threshold andLFA alarm threshold default tolevel-1.Set the type of line idle code ft1 idlecode { 7e | ff } OptionalThe default is 0x7E.Set the type of interframefilling tagft1 itf type { 7e | ff } OptionalThe default is 0x7E.Set the number of interframefilling tagsft1 itf number number OptionalThe default is 4.Set the loopback mode ft1 loopback { local |remote | payload }OptionalLoopback is disabled bydefault.Send remote control loopbackcodeft1 sendloopcode{ fdl-ansi-llb-down |fdl-ansi-llb-up |fdl-ansi-plb-down |fdl-ansi-plb-up |fdl-att-plb-down |fdl-att-plb-up |inband-llb-down |inband-llb-up }OptionalNo remote control code issent by default.To do... Use the command... Remarks
