Core issue
The error message looks similar to this:
%GBIC_SECURITY_CRYPT-4-VN_DATA_CRC_ERROR: GBIC in port [dec] has bad crc.
This message means that the Gigabit Interface Converter (GBIC) module is identified as a Cisco GBIC module, but it does not have a valid cyclic redundancy check (CRC) in the EEPROM data. [dec] is port number or the interface in which the module is installed.
Even if the GBIC module is unrecognized by the system, the GBIC module can still operate properly, but it has limited functionality.
This problem is also termed cosmetic, indicated in Cisco bug ID CSCse25214.
Note: Cisco-approved Small Form-factor Pluggable (SFP) modules have a serial EEPROM that contains the module serial number, the vendor name and ID, a unique security code, and CRC. When an SFP module is inserted in the switch, the switch software reads the EEPROM to verify the serial number, vendor name and vendor ID, and recompute the security code and CRC. If the serial number, the vendor name or vendor ID, the security code, or CRC is invalid, the software generates the security error message and possibly places the interface in an error-disabled state.
Resolution
In order to resolve this, verify that the software release that runs on the system supports the GBIC module. If the GBIC module is newer, a system software upgrade is possibly required.
Refer to LAN Switching Software page in order to download the latest Cisco IOS software release.
