Cabletron Systems CSMIM-T1 - Manual (Page 75)

T-1 Commands
CSMIM-T1 Hardware Installation Guide 4-7
T1_loopback
The superuser T1_loopback command places the T-1 engine into loopback
mode. None of the loopback conditions persist through a power down or
reboot. A major consideration to those using the T-1 service must be made
before using this command since it will completely disrupt the T-1
service. To switch between two different types of loopback, the first
loopback must be cancelled before specifying the second loopback.
The syntax for the T1_loopback command is:
T1_loopback [ none | line | payload | local ]
Table 4-5 describes the arguments for T1_loopback.
Table 4-5 Arguments for the T1_Loopback Command
Argument Description
None No loopback. This is the default. If the T1_loopback
command is initiated with no parameters, then none is
assumed. It cancels any user specified loopbacks.
Line Line loopback provides the network a means to test the
T-1 circuit for single ended fault isolation. The line
loopback regenerates the DS1 signal and does not
correct bipolar violations.
Payload Payload loopback is used to provide a loopback toward
the network. The data portion of the DS0 is looped
back.
Local Local loopback will loop back the data from the
customer side of both the T1 Network Interface and the
T1 Drop/Insert Interface.
Please Note: Network direction loopbacks in most
cases can be initiated by the Telco. The front panel Test
indicator illuminates when the T-1 is in loopback.