The Apollo Domain Protocol is a networking protocol used by the Apollo computer system developed by Apollo Computer Inc. in the 1980s. It is a proprietary protocol that was used primarily for interconnecting Apollo workstations and servers in a local area network.
The Apollo Domain Protocol uses Ethernet as the physical layer and adds a new protocol type (0x8019) to the Ethernet frame. The protocol provides reliable, connection-oriented communication between endpoints using a sequence numbering scheme and acknowledgements.
The source and destination node addresses are encoded in the Apollo Domain Protocol header, which immediately follows the Ethernet header in a packet. The header has the following format:
typedef struct {
uint16_t count;
uint16_t type;