3Com MSR 50 Series Configuration Manual page 343

Analysis
The physical status and protocol status of the interface are not up, or the PVC/XOT
configuration is not correct.
Troubleshooting
First check whether the physical connection status and protocol status of the
■
interface are UP.
If the interface status is DOWN, check whether the physical connections and
■
lower layer configurations are correct.
If the interface configuration is correct, check whether the PVC is configured
■
properly.
If the PVC configuration is also correct, check whether XOT is configured
■
properly.
Troubleshooting X.25 Configuration 343