Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!shadooby!ginosko!cs.utexas.edu!tut.cis.ohio-state.edu!cica!mr
From: mr@cica.cica.indiana.edu (Michael REGOLI)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MNP Level 5 Modems
Message-ID: <186@cica.cica.indiana.edu>
Date: 26 Oct 89 18:24:13 GMT
References: <32171@ucbvax.BERKELEY.EDU>
Organization: Center for Innov. Comp. Appl., Bloomington, IN
Lines: 35

kipnis@janus.Berkeley.EDU (Gary Kipnis) writes:

>Recently I bought Everex 2400 Baud MNP Level 5 Modem, and the manual said
>that if the other line supports MNP Level 5 protocol and if I have compression
>turned on, I can actually achieve higher transfer rates by increasing
>the transfer speed between computer and modem to say 4800 baud.  

>The two questions are:
>How do I find out if the other line supports MNP Level 5 protocol and if
>it does how do I utilize this "speed up"

Gary, if you receive the "CONNECT 2400/REL" message, you have
established a RELiable MNP5 link with the host.  If you see the plain
"CONNECT 2400" you have not.  (Assuming the modem is Hayes-compatible,
issue the command "AT\V1" to enable extended result codes, otherwise
you're liable to see the short version, "23".)

To utilize the "speed up," you need access to a file transfer program
that utilizes error-correcting modems.  In other words, if you use
Kermit or Xmodem, for instance, that *already* use built-in error
correction mechanisms, you WILL NOT notice any improvement in
throughput since the software *and* the modem are producing redundant
error-checking overhead.  (File transfer protocols such as Ymodem-G
and Imodem that are part of ProComm, for instance, do *not* use error
correction schemes and are therefore appropriate for use with
error-correcting modems.)

If anyone has any pointers to non-error correcting software running
under Un*x, I'd appreciate knowing!

--
michael regoli
mr@cica.indiana.edu 
regoli@iubacs.bitnet
...rutgers!iuvax!cica!mr