CRC Error and input Error how can fix these

Unanswered Question
Jan 6th, 2010

FastEthernet0/13 is up, line protocol is up
  Hardware is Fast Ethernet, address is 0004.4d27.66cd (bia 0004.4d27.66cd)
  Description: EDL-P-Box-NO-4
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 250/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Auto-duplex (Full), Auto Speed (100), 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 18:52:43, output 00:00:01, output hang never
  Last clearing of "show interface" counters never
  Queueing strategy: fifo
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  5 minute input rate 12000 bits/sec, 6 packets/sec
  5 minute output rate 24000 bits/sec, 6 packets/sec
     14488019 packets input, 2783320210 bytes
     Received 345346 broadcasts, 0 runts, 0 giants, 0 throttles
     261028 input errors, 259429 CRC, 1599 frame, 0 overrun, 0 ignored
     0 watchdog, 84207 multicast
     0 input packets with dribble condition detected
     19658279 packets output, 3529106068 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

I have this problem too.
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Overall Rating: 5 (3 ratings)
Ganesh Hariharan Wed, 01/06/2010 - 03:13


Check out the below explanation for CRC error and farme error and few useful links to trouble shoot these type of problems

  The CRC error rate is 1.75915% (greater than 1 in a million packets),
  and the collision rate is less than 0.1%.
  This can indicate excessive noise or transmission problems on the LAN or the LAN
  bus itself. A high number of CRCs is usually the result of collisions or a station
  transmitting bad data.

  TRY THIS: Check cables to determine whether any are damaged. If 100BaseTX is being
  used, ensure Category 5 cabling is being used and not another type, such as Category

  There have been 1599 'frame errors' reported.

  This indicates the number of packets received incorrectly, having a CRC error

  and a non-integer number of octets. On a LAN, this is usually the result of collisions

  or a malfunctioning Ethernet device.

TRY THIS: Monitor the level of frame errors over time. If they are increasing,

  try swapping interfaces and or ports to identify the problem.

Hope that helps out your query !!



vvasisth Mon, 01/11/2010 - 03:06

in simple language CRC and input errors refer to Layer 1 issues could be a faulty port or cable.

Check then first.



AKM Fahad Aziz Sun, 08/16/2015 - 21:57

When I turn off my CISCO3825 IPBase router, it shows

Router# CRC Error

Can you please help me to solve this.

My router has 1GB D/256CF.

peter.mainwaring Mon, 01/11/2010 - 06:13

If possible, connect a known good device (maybe a laptop or something) to the wall/floor port that is in question. If the CRC and input errors disappear then the fault is with the NIC on the end device. If CRCs and Input errors are still being generated then there is a fault with the cabling, patch panel or wall socket.


anshulsachdeva Tue, 07/10/2012 - 16:50

Two things I would check if I see the CRC/frame errors:

1.Both the end of the interfaces should have same speed and duplex settings.

2. Check the phyisical cabling , and are the two switches in the same room in DC or different to find out if there

is any media convertor in between . If yes then check the media convertor.

Note Remember- Most of the media convertor does not support fixed speed settings and people dont prefer doing that .so better to make it auto auto( speed and duplex). also check the other end of this interface , can you see the same errors ,

clear the counters and check again.

good luck!

nkarthikeyan Wed, 07/11/2012 - 22:55

This is purely a physical issue...... either a cable issue or the media connected to it or a duplex problem...... verify all the above and check....

Leo Laohoo Wed, 07/11/2012 - 23:10

MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

   reliability 250/255, txload 1/255, rxload 1/255

Don't know why I didn't see this.

It's a cabling issue.

Jose Solano Sat, 11/09/2013 - 15:08


Check this:

1. Check the speed/duplex both the ends

2. Check the cable
3. Check by changing the speed and duplexto half or Auto
4. Chek if the grounding is proper


Karan Puri Mon, 11/11/2013 - 12:01

Leo gave the answer.. see the reliability. ..

@Leo , one question for you.. is test cable tdr n test interface is intrusive commands... can we use it during production time??? Do u have any sample output for this???

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Leo Laohoo Mon, 11/11/2013 - 13:44
@Leo , one question for you.. is test cable tdr n test interface is intrusive commands

I've created a "blog" in regards on how to use TDR

Your question has two answers:  Yes and no.  Yes, it is intrusive particularly when you have old IOS like 12.2(44)SE or earlier/lower.   It is also intrusive if you have a PoE device in one end.  However, if you have newer IOS like 12.2(50)SE and higher (version) or if you have plain Fast- or GigabitEthernet connection, then TDR will not be intrusive.

can we use it during production time

My switches have the latest IOS and I run TDR very regularly during business hours.  Most of the time, it doesn't matter.  If you are running TDR it means something is wrong with the connection so it doesn't matter because the business owner wants the issue rectified no matter what.

Karan Puri Tue, 11/12/2013 - 11:40

@Leo appreciate your doc.. I am searching for test interface doc too...

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guru Dath Wed, 11/13/2013 - 23:58


Whats the distance between the end points,is it greater than 100 meters.then you will face this issue,due to  signal attenuation.

check with cable,duplex,speed.

Bhishma Khanna Fri, 01/10/2014 - 02:57


In your case the input and CRC errors are almost equal

261028 input errors, 259429 CRC

This clearly points to a layer one issue, mosy probable a bad cable which is transmitting the traffic partially and that is why the counters of input errors and CRC are getting hit at same time.



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