From: chrisg@coop.com (Chris Garrigues)
Subject: Re: Microcom QX/3295 and MNP 9 - What is it?
Organization: Cooperative Computing, Inc.
Date: Tue, 29 Dec 1992 22:17:45 GMT

In article <4wscs*Qp1@clumsy.cyvaned.sub.org> tl@clumsy.cyvaned.sub.org writes:
>A few days ago i found a "Microcom QX/3295" modem in a friend's glovebox.
>We tried to make it work but failed - we've found no manual and we don't
>know how to setup the DIP-switches on the rear.  Can anyone give me a hint
>how to make this beast work?
>

I have a QX/4232bis modem here which supports MNP class 10, so I can't
help you with your switch settings, but . . .

>The front panel claims the modem has "MNP class 9" (yes, nine) capability.
>I only know MNP4 and MNP5, so what's this thingy...  ?
>

I can help you with this.  According to the QX/4232bis manual:

MNP Class 2: Class 2 service uses standard asynchronous framing
techniques for data transmission and error correction.  Because of
this protocol overhead, the actual throughput is less than the bps of
the modem.

MNP Class 3: Class 3 service uses sychronous framing techniques.
Start and stop bits associated with each character are removed prior
to transmission by MNP.  This results in a 20% increase in performance
over Class 2 service.  Thus, the actual throughput is greater than the
bps rate of the modem.  For example, a Microcom SX/2400 modem
operating at Class 3 service transmits data at 2600 bps.

MNP Class 4: Class 4 service uses synchronous framing techniques pus
new improvements developed by Microcom: Adaptive Packet Assembly(tm)
and Optimized Data Phase(tm).  These enhancements result in better
performance for all types of connections.

        Adaptive Packet Assembly automatically adjusts the size of the
        data packets based on the quality of the telephone line.  When
        the line quality is good and there are few retransmissions,
        the modem increases the packet size.  When the line quality is
        poor and retransmissions are frequent, the size of the packet
        decreases in order to maintain high throughput during error
        correction under poor conditions.

        Optimized Data Phase is the redesign of the MNP protocol
        header which reduces the number of overhead bytes per data
        packet.

For example, modems operating at Class 4 service transmit data at 2900
bps.

MNP Class 5: Class 5 service provides data compression, which combined
with MNP Class 4 allows throughput of almost twice the connection
speed.  MNP Class 5 Data Compression dynamically adjusts to the type
of data being transmitted for maximum compression efficiency.

MNP Class 6: Class 6 service allows half-duplex, fast-train high-speed
reliable connections with other MNP Class 6 modems at speeds of 4800
to 9600 bps.

        Universal Link Negotiation(tm) allows the modem to
        automatically connect with other MNP modems at the highest
        common speed and protocol.

        Statistical Duplexing(tm) adjusts the line bandwidth and data
        traffic flow during reliable connections to achieve maximum
        throughput, resulting in error-free transmission over 2-wire
        dial-up or leased lines at effective throughputs as high as
        11000 bps on the AX/9600 Plus and 19200 bps on the AX/9624c
        with data compression.

MNP Class 7: Class 7 service provides Enhanced Data Compression, which
combined with Class 4 allows throughput of more than twice the
connection speed.  MNP Class 7 Enhanced Data Compression not only
dynamically adjusts to the type of data being transmitted, but allows
for the probability of character frequency, for superior compression
efficiency.

MNP Class 9: Class 9 service includes enhanced Universal Link
Negotiation.

MNP Class 10: Class 10 Adverse Channel Enhancements (ACP) optimizes
performance when operating under poor line conditions.  MNP Class 10
continues to provide compatibility with non-MNP modems.  It improves
the initial connection success rate by making multiple negotiation
attempts when configured for auto-reliable mode.  It allows the user
to configure the modem to negotiate the link at a low speed
modulation, then upshift to a higher speed at the completion of link
negotiation.  It improves link performance during adverse channel
conditions by aggressive adaptive packet assembly.  It maximizes
throughput by continuously monitoring the line quality and link
performance, and then dynamically upshifting or downshifting to the
optimum modulation speed.


>Any help would much be appreciated.
>--
>tl@clumsy.cyvaned.sub.org (Thomas Lotterer)


Chris Garrigues