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The %MLS_STAT-SP-4-IP_LEN_ERR: MAC/IP length inconsistencies error message is displayed on Cisco Catalyst switches that run Cisco IOS Software


Core issue

The %MLS_STAT-SP-4-IP_LEN_ERR: MAC/IP length inconsistencies error message indicates the receipt of packets whose IP length does not match the MAC length. The Supervisor Engine drops these packets. These packet drops do not cause any negative effects on the switch. The switch reports the error message for informational purposes.

This problem occurs when a device on the network sends out bad packets. These are some of the causes of bad packets:

  • Bad NICs
  • Bad NIC drivers
  • Bad applications


To resolve this issue, perform one of these procedures:

  • Procedure 1: Sniff out the traffic to locate the source of errant packets, and eliminate that traffic source. To achieve this, create a SPAN session for the module number.
  • Procedure 2: Perform these steps on the affected switch:

    1. Issue the no mls verify ip length command to stop the checks for packet length errors.

    2. Issue the no mls verify ip same-address command to stop the check for packets with same source and destination IP addresses.

    Refer to Cisco bug ID CSCdz10360.

For more information, refer to the %MLS_STAT-SP-4-IP_LEN_ERR: MAC/IP length inconsistencies section of Common Error Messages on Catalyst 6500/6000 Series Switches Running Cisco IOS Software.

For further assistance and support, open a service request with Cisco Technical Support.

Error message

%MLS_STAT-SP-4-IP_LEN_ERR: MAC/IP length inconsistencies

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