H3C MSR 20-20 Command Reference Manual page 252

252 C 15: T1-F I C C
HAPTER NTERFACE ONFIGURATION OMMANDS
The format of loopback code can be compliant with ANSI T1.403 or AT&T TR
54016.
In SF framing, LLB code is sent using the effective bandwidth (slots 1 through 24).
In ESF framing, both LLB code and PLB code are sent/received in the FDL in ESF
frames.
You can use this command only when the far-end CT1/PRI interface can
automatically detect loopback request code from the network.
Example # Send in-band LLB activation request code.
<Sysname> system-view
[Sysname] interface serial 2/0
[Sysname-Serial2/0] ft1 sendloopcode inband-llb-up