Specifications

8-3
Cisco MGX 8260 Command Line Interface Guide
Release 1.2, Part Number 78-10987-01 Rev. B0, January, 2002
Chapter 8 Troubleshooting
Performing Loopback Tests
DS3 Loopback
To perform a DS3 loopback test, follow these steps:
Step 1 Activate the loopback using the chds3ln command. Specify the first and last parameters—the slot and
line number, delimited by a period, of the DS1 line and the type of loopback test. Refer to the following
table:
Note Local loopback for DS3 lines is not supported.
For example, the following command loops line 2 on slot 7:
chds1ln 7.2 # # # # 2
The system activates the loopback and changes the corresponding line LED to blinking yellow.
Step 2 Perform DS3 signal tests, as appropriate.
Step 3 Release the loopback by reentering the chds3ln command, but specify the dsx3NoLoop parameter. For
example, to release the loopback on slot 7, line 2, enter the command as follows:
chds3ln 7.2 # # # # 1
The system releases the loopback, changes the line LED to green, and returns the line to normal
operation.
Step 4 Verify that the loopback is clear using the lsds3ln command.
Value Name
1 dsx3NoLoop
2 dsx3PayloadLoop
3dsx3LineLoop
4dsx3OtherLoop