HP MSR2000/3000/4000 Router Series Interface Command Reference

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Usage guidelines
Loopback is mainly used to check the condition of interfaces or cables. Disable loopback in other cases.
The three loopback modes cannot be used simultaneously on a T1-F interface.
Examples
# Set T1-F interface Serial 2/0 in local loopback mode.
<Sysname> system-view
[Sysname] interface serial 2/0
[Sysname-Serial2/0] ft1 loopback local
ft1 sendloopcode
Use ft1 sendloopcode to send remote loopback control code.
Syntax
ft1 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 }
Default
No remote loopback control code is sent.
Views
T1-F interface view
Predefined user roles
network-admin
Parameters
fdl-ansi-llb-down: Sends ANSI-compliant LLB deactivation request code in the FDL to removes loopback.
fdl-ansi-llb-up: Sends ANSI-compliant line loopback (LLB) activation request code in the FDL to start
remote loopback.
fdl-ansi-plb-down: Sends ANSI-compliant PLB deactivation request code in the FDL to remove loopback.
fdl-ansi-plb-up: Sends ANSI-compliant payload loopback (PLB) activation request code in the FDL to start
remote loopback.
fdl-att-plb-down: Sends AT&T-complaint PLB deactivation request code in the FDL to remove loopback.
fdl-att-plb-up: Sends AT&T-complaint PLB activation request code in the FDL to start remote loopback.
inband-llb-down: Sends in-band LLB deactivation request code compliant with the ANSI or AT&T
implementation to remove loopback.
inband-llb-up: Sends in-band line loopback (LLB) activation request code compliant with the ANSI or
AT&T implementation to start remote loopback.
Usage guidelines
You can configure loopback on the remote T1-F interface by sending loopback request code.
In LLB mode, all 193 bits (one synchronization bit and 192 effective bandwidth bits) in a T1 PCM frame
are looped back. In PLB mode, however, only 192 effective bandwidth bits are looped back.
The format of loopback code is compliant with ANSI T1.403 or AT&T TR 54016.