Abstract: Packet sequence numbers of request packets and response packets of transactions transferring data to or from a network interface are tracked. For every request packet transmitted by the network interface, the packet sequence number of the packet is written to a location in a circular send queue pointed to by a write pointer and a valid bit at the location is set. The write pointer is incremented if the packet is a read request packet. Alternatively, a read indicator at the location in the circular send queue pointed to by the write pointer is cleared if the packet is not a read request packet. For every response packet received by the network interface, the packet sequence number of the response packet is checked against the packet sequence number stored at the location in the circular send queue pointed to by the read pointer of the circular send queue.