Troubleshooting

Troubleshooting all ATM connections follows a similar pattern because the greatest strength in ATM, its connection-oriented nature, is also a source of difficulty when those connections fail to materialize.

Because connections are central to successful operation of an ATM network, successful troubleshooting always involves the use of the ATMADM tool. Three steps can lead to a diagnosis of most problems. First, use ATMADM -C to find out whether the connections the computer has are correct.

Second, use ATMADM -A to check that the UNI connection is working correctly. If ATMADM -A returns an address, it proves that you have communicated with the switch, and the switch is aware of the LEC. In rare cases, it is possible to gain an address but still be unable to access any services at the switch; this is due to a very poor quality connection between LEC and switch, and generally indicates a cabling problem.

Finally, if you have no UNI address, use ATMADM -S to determine whether ILMI is operating correctly. If it is, the bottom two entries of the utility report (shown in Figure 14.21) show two incrementing and approximately equal values. "Received" does not increment at quite the same rate as "Sent."