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The "%SYS-3-PORT_IN_ERRORS:" port error message is received in Catalyst 6500 Series Switches that run CatOS software

Core issue

The syntax of this error message is:

%SYS-3-PORT_IN_ERRORS: Port [dec]/[dec] detected [dec] input error(s) in last 30 minutes

This message indicates that a port has experienced an input packet error. [dec]/[dec] is the module number and port number. The third [dec] is the number of frames received on a particular interface with an input packet error in the last 30 minutes.

The port that has these counters incriminating is not able to TX a perfectly good packet to its connected device. This can occur when a port connected to a sever or other heavily used device receives too much data from other switch ports. When this occurs the data will be dropped and re-transmission can occur.

These error messages may indicate the device(s) connected to this specific interface have Layer 1 or Layer 2 issues. The examples of Input Errors are No buffer, Runts, Giants, CRCs, Frame, Overrun, ignored, and Abort counts.


In order to resolve this issue, try this workaround:

  • Issue the show port [mod/port] command in order to verify that the speed/duplex settings are same on both end of the connected interface.

  • Issue the show port jumbo command in order to check that the MTU settings, if any, are configured in that device.


Note: Jumbo frames are frames that are bigger than the standard Ethernet frame size or MTU, which is 1518 bytes. Any messages larger than the MTU are divided into smaller packets before transmission.

  • Try to move the connected device to other available port and check if the error follows the link.

Use the set errordetection portcounters disable command in order to disable this if these messages appear as a result of a change in the code, but, it is better to track the reason why these errors are incrementing in the first place.

Problem Type

Port message received