This read-only counter tracks frames that were intended for forwarding through this port but were discarded because the maximum allowed time to transmission was exceeded. An admin interprets a rising count here as evidence of congestion or delay on the outbound path, where frames are queued too long before the bridge gives up on forwarding them. For example, persistent increases in bdgPortDisTDE on a heavily loaded port would suggest the admin needs to investigate downstream congestion rather than assume a simple hardware fault.