Early retransmission for hardware reliable transport

A network device, comprising:

• an input port;
• an output port;
• and
• circuitry coupled to the input port and the output port, the circuitry being configured to:
• generate a transmitter bitmap comprising a first plurality of data bits, each data bit providing an indication that a given one of a plurality of data packets is transmitted to a second network device;
• receive, from the second network device, a receiver bitmap comprising a second plurality of data bits, each data bit providing an indication that a given one of the plurality of data packets is received or not received;
• and
• compare, at the network device, the bits of the transmitter bitmap to the bits of the receiver bitmap to identify one or more of the plurality of data packets that were transmitted to the second network device but were not received by the second network device,
• wherein the circuitry is further configured to:
• receive, from the input port, an acknowledgment message communicated over the network from the second network device, the acknowledgment message including a timestamp value that provides an indication of when a given data packet of the plurality of data packets was sent by the network device;
• compare the timestamp value to one or more local timestamp values associated with one or more data packets previously sent by the network device to the second network device but not received by the second network device;
• and
• retransmit the one or more data packets for which the comparison indicates has a local timestamp value that is earlier in time than the timestamp value, and
• wherein the circuitry is further configured to:
• determine an unreceived data packet of the one or more data packets that was sent earliest in time;
• and
• transmit, to the second network device, the unreceived data packet sent earliest in time when the difference between the timestamp value for a most recently received packet and the local timestamp value for the unreceived packet sent earliest in time meets or exceeds a threshold.

A network interface card, comprising:

• an input port communicatively coupled to a network;
• an output port communicatively coupled to the network
• circuitry coupled to the input port and the output port, the circuitry being configured to:
• transmit a plurality of data packets to a network device;
• receive, from the input port, an acknowledgment message communicated over the network from the network device, the acknowledgment message comprising a timestamp value that indicates the time that a given data packet of the plurality of data packets was transmitted by the network interface card;
• compare the timestamp value to one or more local timestamp values associated with one or more data packets previously sent by the network interface card to the network device but for which the network device has not acknowledged receipt;
• and
• retransmit the one or more data packets when the difference between the timestamp value and the local timestamp value for the one or more data packets meets or exceeds a threshold.