Troubleshooting Serial Lines
397
Improper or faulty cabling
1. Make sure that you are using the proper cable
for the equipment being used.
2. Use a breakout box to check the control
leads.
3. Swap faulty cables.
Misconfigured interface
1. View the interface configuration using the
show running-config
command.
2. Make sure that the same encapsulation
type is used at both ends of the circuit by
using the show interface command.
Keepalive problems
1. Verify that keepalives are being sent. You
can check this via the router configuration or
by using the show interface command.
2. If the configuration says that keepalives are
being sent, you may want to enable debug
serial interface
for the interface.
3. Verify that the sequence numbers are incre-
menting.
4. If they don't increment, run loopback tests
on the local and remote sites.
5. If the sequences don't increment, even
when the CSU/DSU is in loopback, you have a
hardware problem.
6. Replace faulty hardware.
Hardware failure
1. Replace the hardware.
T A B L E 7 . 2
Action Plans for Common Serial Line Problems (continued)
Problem
Resolution Action Plan
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