Efficient datagram segmentation and reassembly for packet-switched networks

Described herein is datagram segmentation and acknowledgment in a network. A communication node in the network may determine a length of a datagram is greater than a maximum protocol data unit (PDU) length of a protocol of the network and create a segmented message comprising the datagram and a payload length field indicating the length of the datagram. The node may then segment the segmented message into segments and create a PDU comprising one or more of the segments and a segment number least significant bits (LSB) field comprising least significant bits of a segment number associated with the one or more segments. The PDUs may be acknowledged using selective acknowledgment (SACK) messages. The SACK message may comprise a SACK type indicator, a segment number most significant bits (SN_MSB) indicator, and a payload comprising one or more least significant bits (LSBs) of a segment of the segmented message.