*BSD News Article 26726


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From: mrqste01@ucthpx.uct.ac.za (Stephen Marquard)
Newsgroups: comp.os.386bsd.questions
Subject: Bizarre FreeBSD/UUCP comms problem
Date: 1 Feb 1994 13:38:37 +0200
Organization: University of Cape Town
Lines: 53
Message-ID: <2ilevt$kp5@ucthpx.uct.ac.za>
NNTP-Posting-Host: ucthpx.uct.ac.za
Keywords: UUCP Taylor FreeBSD modems comms errors

I don't in fact know if this is a FreeBSD-related problem, but it looks
that way.

Setup: FreeBSD 1.0.2, Taylor UUCP 1.04 (with FreeBSD distribution)
250M IDE h/drive, V32bis external modem with 16550 UART in the serial card, 
386SX-20MHz, 6M RAM

Problem: Incoming UUCP calls, particularly but not exclusively at
2400bps, give persistent errors shortly after transfer starts on
incoming files. With 64 byte packets, the error rate is 1 to 3%, and
rises with larger packet sizes; with 256 byte and above packets, every
2nd packet gets errors sometimes (reported by UUCP Debug as checksum
errors).

The v32bis modem is locked at 19200bps, and the 2400bps connections are
v22bis only, no compression or error correction protocols.

RTS/CTS flow control is enabled on both the modem and computer, and
seems to work. The phone lines are 99.9% noise-free. I can do kermit
transfers with no errors at all, and even do an ASCII upload of a large
uuencoded file with 
  cat >uuefile 
in a shell, and have no errors at all.  (I tested this with a uuencoded
zip file, which unzipped without problems).

UUCICO transfers to a DOS PC running UUPC 1.12b with a null-modem cable work
flawlessly, at 9600bps and 2400bps. Outgoing UUCP calls also work well,
sustaining transfer rates of 1600-1750bps in both directions, although with
the odd checksum error which shouldn't be occurring since the connection is
error-controlled. The machine is under no load at all, doing nothing
except handle UUCP calls.

I have at some stage changed every component of the hardware;
I tried the above system in a 386DX40-MHz machine with 8M RAM, and with
an internal USR Sportster modem instead of the external modem. The
problem doesn't go away.

Lastly, I am familiar with another FreeBSD system which has an almost
identical configuration (exact same copy of uucico, same parameters in
/etc/gettytab and /etc/ttys) which does not produce the problems I
have. I have even tried using the kernel of the error-free FreeBSD
system, and the GENERICAH distribution kernel, but it didn't help.

I have no idea whether this problem is related to software, hardware or
modem configuration.

Does anyone have any ideas?

Stephen Marquard

mrqste01@ucthpx.uct.ac.za
scm@picasso.wcape.school.za