This error occurs when a network adapter (NIC) drops a packet.
When a packet reaches a network adapter, a receive interrupt is generated by the network adapter. When a receive interrupt is generated by a network adapter, the DPC routine is placed in the queue to call the receive handler. Next, the packet is retrieved from the receive buffer at the timing of the DPC interrupt and handed to a higher layer receive handler. If a DPC with a higher priority is being executed or there is a heavy load on the system at this time, there may be a delay before the DPC process is executed making a buffer necessary. If this buffer is not big enough, then a packet is dropped.
In general, this occurs when the server processing speed is not fast enough to keep up with the packet reception rate (packets/sec). When the Initiator (receiving side) drops a packet, it will send a resend request to the Target (sending side). However, if a large number of packets are dropped at once, there may be a large discrepancy between the sequence numbers of the frames that the receiving side requests to be resent and the newest frames that the sending side has sent. When this discrepancy reaches the current receiving window size, the sending side is not able to send any more packets in advance and waits until it receives receive acknowledgement (ACK) for pending frames. After the receiving side receives the frame for which it resent a DUP ACK it does not receive any other frames, so that after waiting the 0.2 seconds of the Delay ACK, it returns the ACK. This results in a 5 frame/sec transmission/reception rate, so that a time out occurs at the Initiator or Target.