Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!mips!apple!rutgers!cbmvax!grr
From: grr@cbmvax.commodore.com (George Robbins)
Newsgroups: comp.unix.ultrix
Subject: Re: Zmodem upload problems
Message-ID: <9136@cbmvax.commodore.com>
Date: 22 Dec 89 07:02:02 GMT
References: <80@ucunix.SAN.UC.EDU>
Reply-To: grr@cbmvax.commodore.com (George Robbins)
Organization: Commodore, West Chester, PA
Lines: 30

In article <80@ucunix.SAN.UC.EDU> rainwatr@ucunix.san.uc.edu (Don Rainwater) writes:
> 
> 	I have a VAX 8650 running Ultrix 3.0.  Terminal connections are
> via DECservers.  My port is running at 19.2k, and my "terminal" is a Mac II.
> The Mac is running ZTerm .85, and I have the rzsz package from 5/89
> running on the Ultrix system.

The best answer is YBF (you be f....d).  The DECservers, especially the DS200
have only small recieve buffers and will quickly overflow when used with a
protocol that tries to send big packets without flow control, especially on a
loaded ethernet.  Zmodem is like this - it tries to ram several big packets,
looking for ack's on the fly and the retrasmit from the first nak or missing
ack.

If you want to do file transfers, either use some dumb protocol with little
packets and per-packet acknowledgement or hook up a direct connect line...

notes:

1) it seemed to work a lot better with 2.2 than 3.x.  CSC just claims it
   probably shouldn't work very well anyway.  I never did pin down whether
   this is just 3.x sluggishness or some extraneous factor at our site.

2) in Ultrix 3.1 (but not previous releases) the LAT driver fails to put
   the server in "PASS ALL" mode when an "stty raw" type call is issued.
   In this case you have to do this manually at your server port.
-- 
George Robbins - now working for,	uucp: {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)