What is fcs error on link?

Basic definition: An FCS error is a legal sized frame with a bad frame check sequence (CRC error). If your link is bad (or if your serial driver is dropping packets), you will see the occasional FCS error. FCS errors usually related to Layer 1 (Physical problem with the link or port); When FCS counter increasing, check the following to identify the root cause. A frame check sequence (FCS) is an error-detecting code added to a frame in a. What is this? My log shows "fcs error" on link attached to an interface. When you see an fcs error it is almost always the cabling on the radio at the other end of the link from where you see the FCS errors.