Digital Data Communications Message Protocol
From Computer History Wiki
The Digital Data Communications Message Protocol (DDCMP) is a byte-oriented data communication protocol for use over full-duplex and half-duplex point-to-point and multi-drop links; principally using using synchronous or asynchronous serial lines, although other communication channels were also supported. It used CRCs to allow transmission errors to be detected; sequence numbers allow detection of completely lost messages. Retransmission is used to correct both.
It was originally designed by DEC for the DECnet Phase I network protocol suite, in 1974. It was retained in later versions of DECnet, with modifications and extensions.
External links
- 'DDCMP Specification Version 4.0', AA-D599A-TC (1 March 1978)
- Digital Data Communications Message Protocol (DDCMP) - Contains a good, detailed description of failure modes
