Frame Check Sequence

What Does Frame Check Sequence Mean?

Frame check sequence (FCS) refers to the extra bits and characters added to data packets for error detection and control.


Network data is transmitted in frames. Each frame is comprised of bits of data appended to the header, which holds basic information such as source and destination media access control (MAC) addresses and application. Another set of characters is added to the end of the frames, which are checked at the destination. Matching FCSs indicate that delivered data is correct.

Techopedia Explains Frame Check Sequence

Because network communication uses varied data transmission media, errors occur on a frequent basis. When data is transmitted in a frame, a specific FCS is added to the frame’s data bits. The source calculates this FCS prior to sending a frame, which is verified and compared at the destination. If the FCS data matches, the transmission is considered successful. If not, the data frame is automatically discarded due to error.

FCS technology is one of the best error control techniques and remains popular because of its simplicity.


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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…