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Core issue

The %EARL_L3_ASIC-SP-3-INTR_WARN: EARL L3 ASIC: Non-fatal interrupt Packet Parser block interrupt error message indicates that a bad packet is received and dropped. This error message is an informational message, and it does not have any impact on the switch performance.

This means that the packet is sourced as a bad packet. The bad packet can be a packet that contains a Layer 3 IP checksum error or a packet in which the IP length does not match the MAC length of the packet or packet with the same source and destination address.

The %MLS_STAT-SP-4-IP_CSUM_ERR: IP checksum error messages indicate that the switch receives tje IP packets with invalid checksum values or IP packets with inconsistent Layer 2/Layer 3 length indication. In both cases, this actually means the Supervisor receives corrupted packets.

There are no ill effects on the switch because the switch drops the packets. The switch reports the error message described for informational purposes.

These packets are normally dropped silently within older Cisco IOS  software. In newer Cisco IOS software releases, this is a new feature enhancement, for example, to display the messages, in order to warn the user that there is or are  devices outside, which send the IP packets with checksum errors and/or with wrong length.

The root of the issue is a device on the network that sends out bad packets. These issues, among others, can cause bad packets:

  • Bad Network Interface Cards (NICs)

  • Bad NIC drivers

  • Bad applications


In order to resolve this issue, try one of these options:

  • Sniff out traffic to find the source of errant packets, then eliminate the traffic source. This is achieved with the creation of a Catalyst Switched Port Analyzer (SPAN) session for the module number.   

  • Perform this workaround on the affected switch:   

    • Issue the no mls verify ip checksum command in order to check for packet checksum errors.
    • Issue the no mls verify ip length command in order to check for packet length errors.
    • Issue the no mls verify ip same-address command in order to check for packets that have equal source and destination IP addresses.

  • Disable the service internal command, if enabled.

If the service internal command is configured, it is known to generate additional logging messages. This mode is mainly used by the Cisco Technical Support and DE in order to further investigate issues on the switch, in engineering mode.

By default, this mode also starts to print the messages on the syslog/console. Consider to disable this mode, which does not affect performance or stability in any way. In order to do this, configure the no service internal command in configuration mode.

For further assistance and support, use the TAC Service Request Tool in order to open a case with Cisco Technical Support.

Error message


%MLS_STAT-SP-4-IP_CSUM_ERR: IP checksum errors

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