khen@TAURUS.BITNET (01/13/89)
I have a PC/XT clone with a dialup modem on an internal
board. The trouble is, this is a simple modem, doing no
error-correction. This is no problem as much as file
transfer is concerned (I can use error-correcting software,
like kermit), but interactive sessions are difficult to
hold, as the phone lines here are very noisy.
I have seen more expensive modems, with the microcom
MNP protocol (MNP == Microcom Network Protocol), and these
virtually elliminate noise at the hardware level, so that
software terminal-emulating programs (such as procomm) are
unaware of it completely. Trouble is, of course, this type
of modem is more expensive. So I am thinking of something
like a TSR program, that "sits" on the communication line
and does the MNP protocol in software, making it possible
for existing terminal-emulating programs to work with it.
Does anyone out there have something like that (source
or binary; free or for sale)?
Please send me any responses by e-mail.
Thanks,
Danny Khenfrank@rsoft.UUCP (Frank I. Reiter) (01/14/89)
On a related topic, can anyone tell me what features are implied by the
different MNP levels? What is the advantage of level 4 vs. 3, or 5 vs. 4?
--
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Frank I. Reiter \ / UUCP: {uunet,ubc-cs}!van-bc!rsoft!frank
Langley, British Columbia / \ BBS: Mind Link @ (604)533-2312
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*Ralf.Brown@B.GP.CS.CMU.EDU (01/15/89)
In article <14@rsoft.UUCP>, frank@rsoft.UUCP (Frank I. Reiter) writes: }On a related topic, can anyone tell me what features are implied by the }different MNP levels? What is the advantage of level 4 vs. 3, or 5 vs. 4? Extract from PD1:<MSDOS.MODEM>MNP-9.ARC on SIMTEL20, itself derived from Microcom product brochures: 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%. A device using MNP Class 1 with a 2400 bps modem will realize 1690 bps throughput. Modern microprocessors have become so powerful that implementations of MNP Class 1 are uncommon in the U.S. 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. Common microprocessor selected for MNP Class 2 implementations are Z80's and 6800's. The protocol efficiency of a Class 2 implementation is about 84%. A device using MNP Class 2 with a 2400 bps modem will realize 2000 bps throughput. Most microprocessor-based hardware can easily implement MNP Class 2. Class 3 MNP Class 3 uses synchronous bit-oriented full-duplex exchange. The synchronous bit-oriented data format is inherently more efficient than the asynchronous byte-oriented data format. It takes 10 bits to represent 8 data bits in the asynchronous data format because of the "start" and "stop" framing bits. The synchronous data format eliminates the need for start and stop bits. The user still sends data asynchronously to the Class 3 modem; meanwhile, the modems communicate with each other synchronously. The protocol efficiency of a Class 3 implementation is about 108%. A device using Class 3 with a 2400 bps modem will realize 2600 bps throughput. At Class 3 performance, the MNP protocol "rewards" the user for using an error-correcting modem by producing 8% extra throughput over an ordinary modem without MNP. Class 4 MNP Class 4 introduces two new concepts, Adaptive Packet Assembly(tm) and Data Phase Optimization(tm), to further improve the performance of an MNP modem. 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 is introducing many errors, then MNP assembles smaller data packets to transmit. while smaller data packets increase protocol overhead, they concurrently decrease the throughput penalty of data retransmissions. The result of smaller data packets is more data is successfully transmitted on the first try. MNP protocol recognizes that during the data transfer phase of a connection, most of the administrative information in the data packet never changes. Data Phase Optimization provides a method for eliminating some of the administrative information. This procedure further reduces protocol overhead. The protocol efficiency of a Class 4 implementation is about 120%. A device using MNP Class 4 with a 2400 bps modem will realize approximately 2900 bps throughput. With class 4 performance, the MNP protocol produces 20% more throughput than an ordinary modem without MNP. 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. The real-time aspects of the algorithm allow the data compression to operate on interactive terminal data as well as file-transfer data. Data compression delivers faster screen updates to the user. A realistic estimate of the overall compression factor a user will experience is 1.6 to 1 or 63%. This is equivalent to having a net protocol efficiency of 200% for an MNP Class 5 implementation. A device using MNP Class 5 with a 2400 bps modem will realize 4800 bps throughput. At MNP Class 5 performance, the MNP protocol produces over 100% more throughput than an ordinary modem without MNP. 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 modulation technology into the same MNP Error-Correcting Modem. Prior to Class 6, MNP was used to enhance current modem technology. MNP Class 6 allows Microcom to create new universal modems. Universol Link Negotiation allows MNP modems to begin operations at a common slower speed and negotiate the use of an alternate high speed modulation technique. The Microcom AX/9624 is an example of a modem that uses Universal Link Negotiation. Universal Link Negotiation uses the 2400 bps V.22bis technology to negotiate a link. At the end of a successful link negotiation for Class 6 operation, the modem shifts to operation using 9600 bps V.29 technology. 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. An MNP Class 6 modem based on V.29 technology delivers maximum performance in file transfer applications; up to 19.2 kbps throughput is possible on dial-up circuits for most applications. In accordance with the principles of MNP, the Class 5 Data Compression is fully incorporated in MNP Class 6. The MNP Class 6 Modem will deliver optimum performance even on an interactive terminal using character echoplexing. Screen updates will occur at speeds between 9.6 kbps andf 19.2 kbps. Most screen updates will take less than a second. Most of the above text was taken from a Microcom Features Description by Mike Focke 7/7/87 Class 7 MNP Class 7 Enhanced Data Compression, combined with Class 4, achieves improved throughput with efficiencies up to 300% via the latest data compression technology. Microcom's enhanced encoding technique not only ndynamically adjusts to the type of data being transmitted, but also predicts the probabality of characters in a data stream. This combined with run length encoding, which sends repeating characters as a single number code, results in the superior compression efficiencies supported in MNP Class 7. Class 8 Nothing available. Class 9 MNP Class 9 utilizes Enhanced Data Compression combined with V.32 technology to deliver maximum throughput up to 300% greater than ordinary V.32 modems. Class 9 also features Enhanced Universal Link Negotiation which allows connection to both MNP and non-MNP modems at the highest performance level. The above was taken from product description buochures from Microcom by Mike Focke 8/1/88 -- UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=- Voice: (412) 268-3053 (school) ARPA: ralf@cs.cmu.edu BIT: ralf%cs.cmu.edu@CMUCCVMA FIDO: Ralf Brown 1:129/31 Disclaimer? I claimed something? You cannot achieve the impossible without attempting the absurd.
felstein@mcnc.org (Bruce M. Felstein) (01/15/89)
The level of MNP refers to exactly what process it is performing. I can summarize the classes as follows: Class 3 - error correction only Class 4 - Data Framing (basically turns async to sync) Class 5 - Data Compression (2:1) Class 6 - Data Compression (3:1) Bruce Felstein | MicroElectronic Center of North Carolina felstein@mcnc.org | The views expressed are my own
ashok@softart.UUCP (Ashok C. Patel) (01/19/89)
> The level of MNP refers to exactly what process it is > performing. > I can summarize the classes as follows: > Class 3 - error correction only > Class 4 - Data Framing (basically turns async to sync) > Class 5 - Data Compression (2:1) > Class 6 - Data Compression (3:1) Not quite right. MNP classes are as follows: Class 1 - error correction using an async half duplex method. That is only one side can send at a given time. (For half duplex modems) Class 2 - error correction using an async full duplex method. Same as the half duplex protocol but both sides can send at the same time. Class 3 - error correction using a synchronous full duplex method. The framing technique here is SDLC. Class 4 - optimization of the packet overheads. This can be run with any of Classes 1-3. It just reduces the packet overheads. Class 5 - data compression (2:1). It can be run with any of Classes 1-4. Class 6 - "ping pong". Meant to be used with a 9600 baud half duplex (9600bps one way only) using the Rockwell 9600 baud FT modem chipset; the channel is used alternately by each side. Class 7 - data compression (3:1). A better form of data compression than Class 5. It can be used instead of Class 5. Class 8 - Protocol enhancements. This is brand new. I don't have many details for this. How do I know this? I write MNP firmware for a *lot* of modem manufacturers for use inside their modem products. > > Bruce Felstein | MicroElectronic Center of North Carolina > felstein@mcnc.org | The views expressed are my own --------------------------- Ashok C. Patel Softart Microsystems Inc.