Cisco Asr 1000 Series Aggregation Services Routers Sip And Spa Software Configuration Guide, Cisco Ios - Cisco ASR 1000 Series Software Configuration Manual

Troubleshooting the Serial SPAs
Table 31: Serial Lines: Increasing Interface Resets on Serial Link
Possible Problem
The following problems can result in this symptom:
Serial Lines: Increasing Carrier Transitions Count on Serial Link
Carrier transitions appear in the output of the show interfaces serial EXEC command whenever there is an
interruption in the carrier signal (such as an interface reset at the remote end of a link).
Symptom: Increasing carrier transitions count on serial link
The following table outlines the possible problems that might cause this symptom and describes solutions to
those problems.
Table 32: Serial Lines: Increasing Carrier Transitions Count on Serial Link
Possible Problem
The following problems can result in this symptom:
OL-14127-17
• Congestion on link (typically associated with
output drops)
• Bad line causing CD transitions
• Possible hardware problem at the CSU, DSU,
or switch
• Line interruptions due to an external source
(such as physical separation of cabling, red or
yellow T1 alarms, or lightning striking
somewhere along the network)
• Faulty switch, DSU, or router hardware
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS XE
Serial Lines: Increasing Carrier Transitions Count on Serial Link
Solution
When interface resets are occurring, examine other
fields of the show interfaces serial command output
to determine the source of the problem. Assuming
that an increase in interface resets is being recorded,
examine the following fields:
1 Check the Carrier Transitions field in the show
interfaces serial command display. If carrier
transitions are high while interface resets are being
registered, the problem is likely to be a bad link
or a bad CSU or DSU. Contact your leased-line
or carrier service, and swap faulty equipment, as
necessary.
2 Examine the Input Errors field in the show
interfaces serial command display. If input errors
are high while interface resets are increasing, the
problem is probably a bad link or a bad
CSU/DSU. Contact your leased-line or other
carrier service, and swap faulty equipment, as
necessary.
If there is a high number of output drops in the show
interfaces serial output, see the
Increasing Output Drops on Serial Link, on page
Solution
1 Check hardware at both ends of the link (attach a
breakout box or a serial analyzer, and test to
determine the source of problems).
2 If an analyzer or breakout box is incapable of
identifying any external problems, check the
router hardware.
3 Swap faulty equipment, as necessary.
Serial Lines:
331.
Everest 16.5
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