Path: utzoo!attcan!uunet!snorkelwacker!apple!voder!nsc!amdahl!rtech!wrs!hwajin
From: hwajin@wrs.wrs.com (Hwa Jin Bae)
Newsgroups: comp.unix.i386
Subject: Re: SLIP for 386/ix
Keywords: SLIP
Message-ID: <856@wrs.wrs.com>
Date: 20 Feb 90 08:24:32 GMT
References: <511187@nstar.UUCP> <82@calcite.UUCP>
Reply-To: hwajin@wrs.wrs.com ()
Organization: Wind River Systems, Emeryville, CA
Lines: 31

In article <82@calcite.UUCP> vjs@calcite.UUCP (Vernon Schryver) writes:
>Vanilla SLIP, as opposed to various "header compression" or "checksumming"
>or "error correcting" varients or the new PPP (RFC-1xxx, I don't remember),
>should not be used with NFS.  The reason is that classic SLIP uses a
>simple 1-byte framing without error detection.  Most varieties of NFS
>(anything based religously on the Sun 4.xBSD reference tapes as well as Sun
>at least until recently) run with UDP checksumming turned off.  This means
>that corrupted bits will not be noticed.  The result is file corruption for
>either the client or on the server's disk.  

This problem can be overcome by patching the SunOS or any other
relevant Unix kernel.  My vanilla SLIP code for our realtime OS 
(called VxWorks) provides okay service for NFS when both sides
turn the UDP checksum on.  So I know NFS works fine once
you turn the UDP checksum on.  It's kinda amusing to use NFS
over 9600 baud line but sometimes it's useful.

Do this on SunOS:
	% su
	% cp /vmunix /vmunix.save
	% adb -w -k /vmunix /dev/mem
	udpcksum?w 1
	^D

And "do the right thing" on your relevant OS to accomplish the 
equivalent effect.

hwajin
-- 
hwajin@wrs.com (uunet!wrs!hwajin)   "Omnibus ex nihil ducendis sufficit unum."
Hwa Jin Bae, Wind River Systems, 1351 Ocean Avenue, Emeryville, CA 94606, USA