Any input error value for cyclic redundancy check (CRC) errors, framing errors, or aborts above 1 percent
of the total interface traffic suggests some kind of link problem that should be isolated and repaired.
Note
Symptom: Increasing number of input errors in excess of 1 percent of total interface traffic
Table 29: Serial Lines: Increasing Input Errors in Excess of 1 Percent of Total Interface Traffic
Solution
Possible Problem
We strongly recommend against the use of
data converters when you are connecting a
router to a WAN or a serial network.
Note
1
Use a serial analyzer to isolate the source of the
input errors. If you detect errors, there likely is a
hardware problem or a clock mismatch in a device
that is external to the router.
2
Use the loopback and ping tests to isolate the
specific problem source.
3
Look for patterns. For example, if errors occur at
a consistent interval, they could be related to a
periodic function, such as the sending of routing
updates.
The following problems can result in this symptom:
•
Faulty telephone company equipment
•
Noisy serial line
•
Incorrect clocking configuration
•
Incorrect cable or cable that is too long
•
Bad cable or connection
•
Bad CSU or DSU
•
Bad router hardware
•
Data converter or other device being used
between router and DSU
Serial Lines: Troubleshooting Serial Line Input Errors
The following table describes the various types of input errors displayed by the show interfaces serial command,
possible problems that might be causing the errors, and solutions to those problems.
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS XE
Everest 16.5
OL-14127-17
333
Troubleshooting the Serial SPAs
Serial Lines: Troubleshooting Serial Line Input Errors