(Microcom Networking Protocol) A family of communications protocols from Microcom, Inc., Norwood, MA, that have become de facto standards for error correction (classes 2 through 4) and data compression (class 5). In 1997, Compaq acquired Microcom.
Half-duplex asynchronous transmission (earlier mode no longer used).
Full-duplex asynchronous transmission.
Full-duplex synchronous transmission using HDLC framing techniques and 64-byte blocks. Start/stop bits are stripped.
Increased throughput. Shorter headers, frames up to 256 bytes. Some vendors adjust frame size based on line quality.
Compresses data up to two times.
Starts at V.22bis modulation and switches to V.29 if possible. Uses pseudo-duplexing ping-pong method for faster turnaround of V.29 transmission.
Compresses data up to three times.
Not in use.
Class 9 - Piggy-back Acknowledgment**
Includes selective retransmission for more efficient data transport. Better performance over a variety of links.
Class 10 - Adverse Channel Enhancements**
Better transmission on rural, cellular and noisy lines.
Class 9 and 10
** = Proprietary Microcom techniques