These messages indicate that the switch forwarding engine receives an IP packet of a length that is less than the minimum allowed length and then drops the packet. In code versions that are earlier than 7.x, the forwarding engine silently drops the packet and counts the packet in the forwarding engine statistics. In code versions that are 7.x or later, this message is recorded in the syslog once every 30 minutes.
There is no effect on the switch side. The switch side drops the bad packet, which the receiving device would have dropped consequently. The only concern is that there is a device that sends bad packets. The possible causes include a bad NIC driver, a NIC driver bug, or a bad application. The Supervisor Engine does not keep track of the source IP address of the device that sends the bad packets. The only way to detect these devices is to use a sniffer in order to track down the source address.
This message is only an informational message and warning from the switch. Issue the set errordetection portcounters disable command on the switch in order to disable these error messages.
from:
http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008014f550.shtml
