3com MSR 20-20 참조 매뉴얼

When the CE1/PRI interface is working as DCE, choose the internal clock (master) 
for it. When it is working as DTE, choose the line clock for it.

# Use the internal clock as the clock source on CE1/PRI interface E1 2/0.

<Sysname> system-view

[Sysname] controller e1 2/0

[Sysname-E1 2/0] clock master 

code { ami | hdb3 }

CE1/PRI interface view

ami: Adopts alternate mark inversion (AMI) line code format.

hdb3: Adopts high density bipolar 3 (HDB3) line code format.

Use the code command to set the line code format for the CE1/PRI interface.

Use the undo code command to restore the default, that is, HDB3.

Keep the line code format of the interface in consistency with that used by the 
remote device.

# Set the line code format of interface E1 2/0 to AMI.

<Sysname> system-view

[Sysname] controller e1 2/0

[Sysname-E1 2/0] code ami 

controller e1 number

System view

number: CE1/PRI interface number.

Use the controller e1 command to enter CE1/PRI interface view.

# Enter E1 2/0 interface view.

<Sysname> system-view

[Sysname] controller e1 2/0

[Sysname-E1 2/0]