Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!hal!ncoast!fmsystm!macy
From: macy@fmsystm.UUCP (Macy Hallock)
Newsgroups: comp.dcom.modems
Subject: Re: MNP 5 vs. uucp 'g'
Summary: not all uucico's accept t or e protocol
Keywords: MNP error modem
Message-ID: <38@fmsystm.UUCP>
Date: 7 Sep 89 01:01:47 GMT
References: <124236@sun.Eng.Sun.COM>
Reply-To: macy@fmsystm.UUCP (Macy Hallock)
Organization: F M Systems  Medina, Ohio USA
Lines: 43

In article <124236@sun.Eng.Sun.COM> shannon%datsun@Sun.COM (Bill Shannon) writes:
> [description of MNP 5 incompatiblilty with uucp g protocol deleted]
>
>Have any of you people using MNP 5 (or higher) run into the same problem?

Yes, I have run into this.  You description is basically correct.

>In particular, I've seen some claims of fantastic throughput using the
>Microcom modem at 38400 baud with MNP 9.  Are people using uucp's 'g'
>protocol in this configuration?  Does MNP 9 not have this problem?

We are testing some error correcting V.32 modems at this time.
It would appear that uucp g usually works on them, but there is
still some delay added over using t or e protocol.

>You might think that, since the modem is providing error correction, you
>could use one of the uucp error-free protocols ('t' or 'e').  In fact,
>using one of those protocols does give the expected throughput.  However,
>the modems only guarantee that the data makes it from one modem to the
>other without errors; there is no guarantee that the data will make it into
>the host without errors.  While I'm not really worried about "line noise"
>corrupting the data between the modem and the host, I am worried that the
>host can drop data coming from the modem, for instance the familiar "silo
>overflow" problem if the host gets too busy.  As far as I can tell, the
>uucp error-free protocols won't detect this condition, thus possibly
>resulting in corrupted files being transferred.  Has anyone else considered
>this problem and perhaps dealt with it?

You're right again.  And I have found several versions of uucico that
do not support t or e protocols (SCO comes to mind, for one).  Unless
carefully considered, the use of two error detection schemes on a datacom
link degrades performance.  

Use of the Microcom V.32 with MNP 5 for SLIP seems to work well.

Regards,
       Macy Hallock               fmsystm!macy@NCoast.ORG
       F M Systems, Inc.          hal!ncoast!fmsystm!macy
       150 Highland Dr.           uunet!hal.cwru.edu!ncoast!fmsystm!macy
       Medina, OH 44256           Voice: 216-723-3000 X251  
       Disclaimer:                My advice is worth what you paid for it.
       Alt.disclaimer:            Your milage may vary.
       Biz.disclaimer:            My opinions are my own. What do I know?