3com MSR 20-20 참조 매뉴얼

CT1/PRI interface view

local: Enables the CT1/PRI interface to perform local loopback.

payload: Enables the interface to perform external payload loopback.

remote: Enables the interface to perform remote loopback.

Use the loopback command to enable local, remote, or external payload 
loopback on the CT1/PRI interface.

Use the undo loopback command to restore the default.

By default, loopback is disabled.

Loopback is intended for checking the condition of interfaces or cables. Disable it 
otherwise.

You can bundle timeslots on a CT1/PRI interface to form a serial interface and 
encapsulate it with PPP. After you enable loopback on this serial interface, it is 
normal that the state of the link layer protocol is reported down.

# Enabled remote loopback on interface T1 2/0.

<Sysname> system-view

[Sysname] controller t1 2/0

[Sysname-T1 2/0] loopback remote 

pri-set [ timeslot-list list ]

CT1/PRI interface view

list: Specifies timeslots to be bundled. Timeslots are numbered 1 through 24. You 
may specify a single timeslot by specifying a number, a range of timeslots by 
specifying a range in the form of number1-number2, or several discrete timeslots 
by specifying number1, number2-number3.

Use the pri-set command to bundle timeslots into a PRI set on the CT1/PRI 
interface.

Use the undo pri-set command to remove the timeslot bundle.

By default, no PRI set is created.