Internal protocol CRC Checksums
This event is triggered when the number of CRC errors per second is higher than the value configured in the Expert Thresholds setup.
Some protocols (TCP/IP for example), have a second (in addition to the MAC frame CRC checksum) checksum for data integrity purposes. This checksum is calculated on only a portion of the internal data of each packet, and can give a second and independent check for the validity of the packet's contents. Observer calculates this checksum independent of the MAC layer CRC and displays the results in the decode display.
These CRC errors are very rare and can be caused by malfunctioning software or protocol drivers.
Possible reasons for the event:
a bad Ethernet card or router connection NIC
bad cabling between station and hub/switch, a cable that is too long or electrical interference on the cable