Dickson@his-phoenix-multics.arpa.UUCP (03/03/87)
I was looking through the March issue of Byte today, specifically
looking for prices of modems which supported MNP. I only found it
advertised in two spots, but one was class 3 MNP while the other was
class 4. Can somebody describe what the differences are?
Also, in one of the advertisements, it states that MNP is in public
domain. Can someone tell me how I can go about getting a copy of the
description of the protocol?
Thanks in advance for any help.
Paul Dickson
Dickson%pco at BCO-Multics.ARPAlong@SH.CS.NET.UUCP (03/07/87)
To quote Microcom glossies:
Class 4:
--------
Two new techniques found in our new Class 4 modems result in increased
throughput over current MNP Class 3 modems.
First, Adaptive Packet Assembly constantly monitors phone line
conditions for noise and interference. It then automatically adjusts
data packet size, continually optimizing the packet size relative to
the number of retransmissions caused by noisy lines. This process is
totally transparent to the user.
Second, as part of our continuing refinement of MNP, Microcom software
engineers have further optimized data throughput by minimizing
protocol overhead.
These two new techniques result in 10-15% increased throughput over
current Class 3 Modems.
Class 4 Modems include the AX/1200 and AX/2400 modems.
Class 5:
--------
MNP Class 5 products include the AX/2400c modem.
Microcom Class 5 products come with all of the advantages of Class 4
modems plus a new compression technique that encodes data, effectively
allowing it to be transmitted at speeds in excess of 4800bps.
Of course, when not in compression mode, the AX/2400c is compatible
with 2400 and 1200 bps modems.
Class 6:
--------
MNP Class 6 products include the AX/9612c and AX/9624c modems.
These products have everything Class 4 and 5 have plus two new
advantages that result in significantly greater throughput and maximum
flexibility.
Statistical Duplexing (TM) allows Class 6 modems to adjust line
bandwidth and data traffic flow automatically to achieve maximum
throughput. Not only are these modems the first to perform at 9600bps
over normal dial lines, they can also reach error-free transmissions
speeds as high as 19,200bps.
Universal Link Negotiation (TM) permits Class 6 modems to connect with
most popular dial-up modems -- and then negotiate up or down to the
highest mutually acceptable speed. This gives MNP Class 6 modems
maximum compatibility and flexibility, which achieving the greatest
possible data transfer speed.
MNP Availability (from Microcom Distributer News, Volume II, 12/84)
-------------------------------------------------------------------
"Vendors may license the protocol for a one-time fee of $2500."
(I think this was at a time when only up to Class 3 was available).
For more info about MNP, write:
-------------------------------
Microcom, Inc.
1400A Providence Highway
Norwood, MA 02062
(617) 762-9310
(My only connection with Microcom is that we've used their modems.)
Hope this helps,
Dan Long
CSNETSIMON1@HBUNOS.BITNET (Simon Shickman) (03/08/87)
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.