3Com 3031 Command Reference Manual page 202

202 C 3: I M C
HAPTER NTERFACE ANAGEMENT OMMANDS
Description
Using the t1 set frame-format command, you can configure the frame format of
T1 line. Using the undo t1 set frame-format command, you can restore the default
setting.
By default, the frame format of T1 line is esf.
Only if a T1 line is working in framed format (which can be set by using the undo
t1 unframed command) can this command be configured.
For the related commands, see t1 set unframed and using.
Example
Adopt the frame format SF for the first T1 line on the T3 interface.
[3com-T3 1/0/0]t1 1 set frame-format sf
t1 set loopback Syntax
t1 line-number set loopback { local | remote }
undo t1 line-number set loopback
View
CT3 interface view
Parameter
line-number: T1 line number in the range of 1 to 28.
local: Enables the T1 line to perform local loopback.
remote: Enables the T1 line to perform remote loopback.
Description
Using the t1 set loopback command, you can set the loopback mode of a T1 line
on a T3 interface. Using the undo t1 set loopback command, you can disable the
T1 line to loop back.
By default, T1 lines are disabled to loop back.
If a T1 line encapsulated with PPP has been set to perform loopback, it is normal
for the state of its link layer protocol to be reported as DOWN.
Loopback is usually used for some special tests. It should not be enabled in normal
working condition.
Example
Set the loopback mode on the first T1 line on the T3 interface to local.
[3com-T3 1/0/0]t1 1 set loopback local