Troubleshooting CRC Error Packets on an Interface

Introduction

In data communication, the receive end needs to detect whether any error occurs during data transmission. Common technologies for the error detection include parity check, checksum, and cyclic redundancy check (CRC). The transmit end calculates the verification code based on a certain algorithm and sends the verification code and message to the receive end. The receive end obtains the verification code from the received message based on the same algorithm and compares the verification code with the received verification code to determine whether the received message is correct.

That is, the CRC error packet statistics indicate the number of times the verification nodes obtained by the transmit and receive ends using the CRC mode do not match.

<HUAWEI> display interface 10ge 1/0/1
10GE1/0/1 current state : DOWN (ifindex: 36)
Line protocol current state : DOWN
Description:
Switch Port, PVID :    1, TPID : 8100(Hex), The Maximum Frame Length is 9216
Internet protocol processing : disabled
IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 00a0-c945-6101
Port Mode:             AUTO,     Port Split/Aggregate:               -
Speed:                 AUTO,     Loopback:                        NONE
Duplex:                FULL,     Negotiation:                        -
Input Flow-control: DISABLE,     Output Flow-control:          DISABLE
Mdi:                      -,     Fec:                                -
Last physical up time   : -
Last physical down time : 2015-01-03 18:50:04
Current system time: 2015-01-03 23:09:54
Statistics last cleared:never
    Last 10 seconds input rate: 0 bits/sec, 0 packets/sec
    Last 10 seconds output rate: 0 bits/sec, 0 packets/sec
    Input peak rate 0 bits/sec, Record time: -
    Output peak rate 0 bits/sec, Record time: -
    Input :                  0 bytes,                  0 packets
    Output:                  0 bytes,                  0 packets
    Input:
      Unicast:                      0,   Multicast:                       0
      Broadcast:                    0,   Jumbo:                           0
      Discard:                      0,   Frames:                          0
      Pause:                        0

      Total Error:                  0
      CRC:                          0,   Giants:                          0
      Jabbers:                      0,   Fragments:                       0
      Runts:                        0,   DropEvents:                      0
      Alignments:                   0,   Symbols:                         0
      Ignoreds:                     0
  ---- More ----

Procedure for Handling CRC Error Packets

Save the results of each troubleshooting step. If the fault persists after following this procedure, Huawei will need these results for further troubleshooting.

1. Check the configuration and status of the local and remote interfaces.

   Run the display this interface command multiple times in the interface view to check the interface status, and check whether the discarded packet count and CRC error packet count at the physical layer keep increasing stably. The CRC error packets are usually caused by interference of network cables. If the error packet count keeps increasing, check the cable quality first. It is normal if a few CRC error packets are received. This is often caused by poor contact of network cables. In this case, remove and reinstall the cables.

   Ensure that optical interfaces at both ends of a link work in the same auto-negotiation mode. If they work in non-auto-negotiation mode, ensure that the interfaces work at the same rate and in the same duplex mode.

2. Run the display interface transceiver verbose command to check whether the wavelengths of the optical modules at both ends are the same and whether the optical module information, such as the power, is normal.

   <HUAWEI> display interface transceiver verbose
    10GE1/0/1 transceiver information:
   -------------------------------------------------------------------
    Common information:
      Transceiver Type                      :10GBASE_SR
      Connector Type                        :LC
      Wavelength (nm)                       :850
      Transfer Distance (m)                 :30(62.5um/125um OM1)
                                             80(50um/125um OM2)
                                             300(50um/125um OM3)
                                             400(50um/125um OM4)
      Digital Diagnostic Monitoring         :YES
      Vendor Name                           :JDSU
      Vendor Part Number                    :PLRXPLSCS4322N
      Ordering Name                         :
   -------------------------------------------------------------------
    Manufacture information:
      Manu. Serial Number                   :CB45UF0V2
      Manufacturing Date                    :2011-11-8
      Vendor Name                           :JDSU
   -------------------------------------------------------------------
    Alarm information:
   -------------------------------------------------------------------
     ---- More ----

3. Remove and reinstall the optical fibers and optical modules and check whether the fiber connectors are damaged or contaminated, to determine whether the CRC error packets are caused by poor contact.

   It is recommended that idle fiber connectors be covered with dust-proof caps to keep the fiber connectors clean. An unclean fiber connector may degrade the quality of optical signals or even cause link failures or error codes on the link.

4. Check whether the optical fiber length is within the allowed transmission distance range of the optical module. If the transmission distance between two optical modules exceeds the maximum distance they support, alarms on low optical power will be generated even if the optical modules have the same wavelength.

   In the command output in step 2, the Transfer Distance field indicates the transmission distance supported the optical module. View this field to determine whether the optical fiber length is within the allowed transmission distance range of the optical module. For example, in the preceding command output, the transmission distance supported by the OM1 optical fiber is 30 m. If the actual transmission distance exceeds 30 m, use an optical fiber with a longer transmission distance.

5. Check whether the optical modules of the local and remote interfaces match the optical fibers connected to them.
   Multimode optical modules must be used with multimode optical fibers. Single-mode optical modules are generally used with single-mode optical fibers, and can also be used with multimode optical fibers. If a single-mode optical module is used with a single-mode optical fiber, the transmission distance is often longer than 10 km.

   Generally, a single-mode optical fiber is yellow, and a multimode optical fiber is orange.

   Generally, the handle of a multimode optical module is black and that of a single-mode optical module is blue. You can also view the label attached to an optical module to check whether it is a single-mode or multimode optical module. SM and MM indicate single-mode and multimode, respectively.

6. Check whether the local and remote interfaces use optical modules of different types from different vendors.

   If the optical modules have the same wavelength and the transmission distance between them is within the allowed range, but alarms on high or low optical power are still generated, the two optical modules may be from different vendors and of different types. Although they have same wavelength, their optical power specifications may be different due to different designs adopted by the vendors. This may also cause alarms on abnormal optical power. Replace the optical modules with optical modules of the same type certified for Huawei Ethernet switches.

Related Information

For more information about this problem and corresponding solutions, see the following document:

The Number of Error Packets Increases on an Interface of a CE6800 Series Switch