What does the Frame Check Sequence (FCS) add to a data frame?

The Frame Check Sequence (FCS) plays a critical role in ensuring data integrity within a data frame by providing error detection capabilities. It does this by appending a calculated value to the end of the frame, which represents a checksum of the frame's contents. When the frame reaches its destination, the receiving device recalculates the FCS based on the received data. If the FCS values match, it indicates that the data has likely not been corrupted during transmission. If they do not match, it suggests that an error has occurred, prompting the system to discard the frame and potentially request a retransmission.

This function is essential in network communication as it helps maintain the reliability and accuracy of data being transmitted, ensuring that any discrepancies caused by noise, interference, or other transmission errors can be identified and handled appropriately.