3Com SuperStack II manual Start the loopback test by entering, To stop the loopback test, enter

136APPENDIX A: TROUBLESHOOTING

Before running the CSU/DSU loopback test:

■Attach a console or Telnet to your bridge/router.

■Cable your WAN port to the telco network.

■Make sure the device you are connecting to supports V.54 loopback and is in loopback mode.

To perform a V.54 loopback test on the built-in CSU/DSU, follow these steps:

1Diasble the path by entering:

SETDefault !3 -PATH CONTrol = Disable

2Start the loopback test by entering:

SET -SYS V54Lback = YES

SET -SYS V54Lback = START

The loopback test runs for approximately one minute. If the loopback test was successful, the following message is displayed:

V.54 data loopback succeeded

If the destination device does not respond, the following message is displayed:

V.54 local loopback terminated - remote site not responding

If the data is corrupted and the line is not error free, the following message is displayed:

V.54 data loopback failed - check for documented errors

If this message is displayed, contact your line provider for help.

If the local unit cannot transmit data at that particular time, the following message is displayed, and you should try again later:

V.54 SCC Transmit failed

3To stop the loopback test, enter:

SET -SYS V54Lback = STOP

4If you want to enable V.54 detection so that a remote unit can initiate a

V.54 loopback test, enter:

SET -SYS V54Lback = YES

5To disable V.54 detection, enter:

SET -SYS V54Lback = NO