This read-write integer sets the ingress queue depth, in bytes, above which arriving cells are marked discard-eligible, ranging up to 0x1fffff bytes on FRSM-VHS cards but limited to 0xffff bytes elsewhere, and unsupported on FRSM12 cards. It lets an administrator decide how aggressively to mark traffic as expendable before the queue actually overflows, which protects higher-priority traffic when the ingress buffer starts filling. For instance, lowering ingressQDEThresh on a congested FRSM-VHS port would cause frames to be DE-marked sooner, well before they approach the queue's full 0x1fffff-byte capacity.