This Counter64 counts octets discarded at ingress for exceeding this circuit's traffic contract, the byte-volume counterpart to circuitInFramesDiscard, letting an admin quantify actual data loss in bytes rather than just frame counts. Combined with circuitInOctets, this lets an admin compute a byte-loss percentage for the circuit, which is often a more meaningful capacity-planning metric than a frame-loss percentage when frame sizes vary. For example, a small percentage of frames discarded (from circuitInFramesDiscard vs circuitInFrames) but a disproportionately large percentage of octets discarded here would suggest it's specifically large frames that are being dropped, perhaps bulk transfers rather than small control packets.