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From: SIMON1@HBUNOS.BITNET (Simon Shickman)
Newsgroups: comp.dcom.modems
Subject: Re: MNP classes
Message-ID: <8703081135.AA24691@ucbvax.Berkeley.EDU>
Date: Sun, 8-Mar-87 06:35:27 EST
Article-I.D.: ucbvax.8703081135.AA24691
Posted: Sun Mar  8 06:35:27 1987
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MNP is Microcom Networking Protocol.
When an MNP communications link is being established, the two MNP
implementations will negotiate to operate at the highest mutually supported
class of MNP service.

I think that only MNP class 1,2 and 3 are in public domain.

The following performance comparison description is from MICROCOM.

CLASS 1

This is the first level of MNP performance. MNP Class 1 uses an asynchronous
byte-oriented half-duplex method of exchanging data. MNP Class 1
implementations make minimum demands on processor speeds and memory storage.
MNP Class 1 makes it possible for devices with small hardware configurations
to communicate error free.
The protocol efficiency of a Class 1 implementation is about 70%.

CLASS 2

MNP Class 2 uses asynchronous byte-oriented full-duplex data exchange.
Almost all microprocessor based hardware is capable of supporting MNP
Class 2 performance.
The protocol efficiency of a Class 2 implementation is about 84%.

CLASS 3

MNP Class 3 uses synchronous bit-oriented full-duplex data exchange.
The synchronous bit-oriented data format is inherently more efficient
than the asynchronous byte-oriented data format.
The protocol efficiency of a Class 3 implementation is about 108%.

CLASS 4

MNP Class 4 introduces two new concepts, Adaptive Packet Assembly(tm)
and Data Phase Optimization(tm). During data transfer, MNP monitors the
reliability of the transmission medium. If the data channel is relatively
error-free, MNP assembles larger data packets to increase throughput.
If the data channel is introducing many errors, then MNP assembles
smaller data packets to transmit.
Data Phase Optimization provides a method for eliminating some of the
administrative information.
The protocol efficiency of a Class 4 implementation is about 120%.

CLASS 5

MNP Class 5 introduces Data Compression as a new feature to MNP Class 4
service. MNP Data Compression uses a real-time adaptive algorithm to
compress data.

CLASS 6

MNP Class 6 introduces the new features Universal Link Negotiation(tm) and
Statistical Duplexing(tm) to MNP Class 5 service.
Universal Link Negotiation allows MNP to unify non-compatible modem technology
into the same MNP error-correcting modem.
Universal Link Negotiation allows MNP modems to begin operations at a common
slower speed and negotiate the use of an alternate high speed modulation
technique. (start with 2400 bps V.22 bis and then shift to 9600 bps V.29)
In the case where the high-speed carrier technology uses half-duplex modulation
MNP Class 6 provides Statistical Duplexing. The Statistical Duplexing
algorithm monitors the user data traffic pattern to dynamically allocate
utilization of the half-duplex modulation to deliver full-duplex service.