Specifications

Troubleshoot the T3 and T1 Channels
Configuring Serial Interfaces IC-85
Troubleshoot the T3 and T1 Channels
You can use the following methods to troubleshoot the CT3IP using Cisco IOS software:
• Test the T1 by using the t1 test controller configuration command and the test port.
• Loop the T1 by using loopback interface configuration commands.
• Loop the T3 by using loopback controller configuration commands.
Enable Test Port
You can use the T1 test port available on the CT3IP to break out any of the 28 T1 channels for testing
(for example, 24-hour BERT testing as is commonly done by telephone companies before a line is
brought into service).
The T1 test port is also available as an external port. For more information on configuring an external
port, see the previous section, “Configure External T1 Channels.”
Note If a T1 channel that was previously configured as a serial interface is broken out to the T1 port
test, that interface and its associated configuration remain intact while the channel is broken out to
the T1 port test. The serial interface is not usable during the time the T1 channel is broken out to the
T1 test port; however, the configuration remains to facilitate the return of the T1 channel to a serial
interface with the no t1 test command.
To enable a T1 channel as a test port, use the following commands beginning in global configuration
mode:
To disable a T1 channel as a test port, use the following commands beginning in global configuration
mode:
Step Command Purpose
1 show controller t3
slot/port-adapter/port
Determine if the external device connected to the
external T1 port is configured and cabled correctly by
locating the line
Ext1... in the display output. If the
line status is
OK, a valid signal is being received and
the signal is not an all-ones signal.
2 controller t3 slot/port-adapter/port Select the CT3IP and enter controller configuration
mode.
3 t1 test channel [cablelength feet]
[linecode {ami | b8zs}]
Enable the T1 channel (values are 1 to 28) as a test port
and optionally specify the cable length and line code.
The default cable length is 133 feet, and the default
line code is b8zs.
Step Command Purpose
1 controller t3 slot/port-adapter/port Select the CT3IP and enter controller configuration
mode.
2 no t1 test channel Disable the T1 channel (values are 1 to 28) as a test
port.