This read-only counter, in frames, tallies frames for which this switch itself set the DE bit, marking a frame discard-eligible because it exceeded the contract while passing through this switch, rather than arriving already marked. Unlike casfVcCountReceivedDEs, which counts frames arriving already marked by someone else, this rising means traffic entering this switch on this VC is exceeding its committed rate at this hop specifically. This counter climbing on a VC whose ReceivedDEs stays at zero shows the customer's traffic wasn't marked before reaching this switch, but is being caught as excess right here.