This field records how much the counter for FCoE frames the adapter attempted to send but discarded instead of transmitting increased during the most recent collection interval, rather than the lifetime cumulative total. For a network admin, this usually tracks a congested or paused fabric-facing uplink, since FCoE relies on Ethernet PFC pause frames to avoid loss and a spike here means that pause mechanism is being overwhelmed. For example, 5 frames in the last interval on this specific FCoE path would already be worth a closer look, since this counter should normally sit at or near zero.