How to handle the CRC errors? Highlighted

Latest reply: Oct 30, 2018 08:37:17 2180 11 11 0

This post describes the process of how to handle the CRC errors. Please have a look below to find the solution.

Issue description

Fault diagnostic: The switch is reporting a lot of CRC errors on some interfaces and some packets are lost due to this issue.

You can use display interface xxxx to check the CRC errror statistics.


Most probably, the CRC issue is caused by the hardware part, as it is not a software issue. There are some reasons which can cause the CRC issue, such as the transceiver not being inserted tightly, the fiber or cable being twisted too much, the transceiver being unstable, or the hardware of this port being unstable on the switch.

To handle the CRC issue, the best way is to do the cross-test:

1. firstly check the transceiver and fiber to see if they are tightly connected. You can plug out and plug in to test again;

2. move the transceiver to other ports on the switch; if the CRC still persists, it means that the CRC is related to the transceiver or fiber. If CRC disappears, it means that maybe the hardware of this port is unstable. We can find another good transceiver to test again if the CRC still happens even if we replace with another good transceiver. In this case, we can replace the switch;

3. after step 2, if the CRC still occurs even after moving to other ports, it means that this may be related to a transceiver issue. We can replace it with another good transceiver; if the CRC disappears, then it's related to the faulty transceiver.\

CRC may be related to a peer device also in case that the transceiver is not connected to peer switch tightly or the hardware of the port is unstable on peer switch. We can find another good transceiver to test on the peer switch; if the CRC still happens even if we test with another good transceiver, we can say the hardware of this port is unstable.

  • x
  • convention:

Created Oct 18, 2018 02:18:03 Helpful(0) Helpful(0)

This post was last edited by yjhd at 2018-10-31 07:43.

CRC error means physical link has problem? if so, maybe solved one issue of mine

  • x
  • convention:

Created Oct 18, 2018 02:21:52 Helpful(0) Helpful(0)

This post was last edited by Torrent at 2018-10-31 07:21.

The crc-alarm enable command enables the alarm function for CRC errors on the AP wired interface and specifies the alarm threshold and clear alarm threshold.

The undo crc-alarm enable command disables the alarm function for CRC errors on the AP wired interface and restores the alarm threshold and clear alarm threshold to the default values.

By default, the alarm function for CRC errors is disabled on the AP wired interface. The alarm threshold for CRC errors is 50 and the clear alarm threshold is 20.

  • x
  • convention:

Created Oct 18, 2018 05:06:10 Helpful(0) Helpful(0)

Thanks for sharingHow to handle the CRC errors?-2779957-1
  • x
  • convention:

If you think my post/reply is useful, please click the Helpful button and flag my post as a BEST ANSWER. Thanks
Created Oct 18, 2018 09:20:38 Helpful(0) Helpful(0)

This post was last edited by SupperRobin at 2018-10-31 06:55. When the Device detects that the number of CRC errors exceeds the configured upper alarm threshold in a specified period, it sends an alarm message to the AC. To prevent the AP from frequently sending alarm messages or alarm clearance messages to the AC, you need to configure the lower threshold for clearing the alarm. The AP sends an alarm clearance message to the AC only when the AP detects that the number of CRC errors is lower than the configured lower threshold.
  • x
  • convention:

MVE Created Oct 18, 2018 17:13:16 Helpful(0) Helpful(0)

Good work, thanks
  • x
  • convention:

Created Oct 19, 2018 03:30:05 Helpful(0) Helpful(0)

This post was last edited by No.9527 at 2018-10-31 06:46. In a stack system, if a stack port continuously receives CRC error packets or flaps between Up and Down states, the corresponding stack link cannot forward traffic normally, thereby affecting network services. This command enables the stack port error-down function. This function can shut down a stack port and switch traffic to other stack links if the rate of received CRC error packets or the number of Up/Down transitions on the stack port reaches the specified threshold, reducing the impact on services. Additionally, the system generates stack port error-down alarms to help in fault location.
  • x
  • convention:

Created Oct 19, 2018 09:45:10 Helpful(0) Helpful(0)

This post is novel in concept, with unique ingenuity, clear passages, different plots, ups and downs, distinct lines, fascinating and fascinating literary skills. It can be described as a word and a classic sentence, which is a model that my generation should learn.
I was already disappointed with this community. I feel that this community has no future, and my heart is full of sorrow. But after reading this post, I made hope for the community. It is you who let my heart rekindle the fire of hope. It is you who have revived my heart. You saved me a cool and cool heart!
Originally, I decided not to return any posts in the community, but after reading your post, I told myself that this post must be returned! This is a rare sticker that has been rare for a hundred years! Heaven has eyes, let me see such a wonderful post in the eugenic year.
  • x
  • convention:

Created Oct 22, 2018 07:03:25 Helpful(0) Helpful(0)

Hi there guys!
Just to update the topic:
- CRC can be related due to Fiber cable connectors are not clean enough.
- Maybe the Optical Tx/Rx level of the SFP is not Ok
- Maybe even distance between network elements is larger the SFP supported (especially Multimode SFP)
So, please, do not just change one single SFP inside single chassis - look for the whole physical path.
  • x
  • convention:

Created Oct 23, 2018 04:07:04 Helpful(0) Helpful(0)

This post was last edited by littlestone at 2018-10-31 06:08. Determine the forwarding mode of packets.
  • For CE8800&CE7800&6800&5800 series switches exclude CE6870EI and CE6875EI, hash modes can be configured for known and non-known unicast packets separately. First check whether packets are known or non-known unicast packets
  • x
  • convention:

Back to list


You need to log in to reply to the post Login | Register

Notice Notice: To protect the legitimate rights and interests of you, the community, and third parties, do not release content that may bring legal risks to all parties, including but are not limited to the following:
  • Politically sensitive content
  • Content concerning pornography, gambling, and drug abuse
  • Content that may disclose or infringe upon others ' commercial secrets, intellectual properties, including trade marks, copyrights, and patents, and personal privacy
Do not share your account and password with others. All operations performed using your account will be regarded as your own actions and all consequences arising therefrom will be borne by you. For details, see " Privacy."
If the attachment button is not available, update the Adobe Flash Player to the latest version!
Login and enjoy all the member benefits

Login and enjoy all the member benefits