Configuring the Data Link Layer Protocol for E1, T1, and Serial Interfaces
Troubleshooting Logical Interfaces
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Troubleshooting Logical Interfaces
If the physical interface is up but the logical interface is not, the steps you take
to troubleshoot the problem vary, depending on the Data Link Layer protocol
you are using. This section is organized into three sections:
troubleshooting the PPP interface
troubleshooting the Frame Relay interface and subinterface
troubleshooting the HDLC interface
Enter the show and debug commands described in this troubleshooting
section from the enable mode context. You can also access these commands
from any configuration mode context by adding do to the beginning of the
command.
Troubleshooting the PPP Interface
The first tool in troubleshooting a logical interface is the show interfaces
command. From the enable mode context, enter the following command to
check the status of a PPP interface that is bound to the E1, T1, or serial
interface:
Syntax: show interfaces ppp <number>