Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!pasteur!ucbvax!XX.LCS.MIT.EDU!LENOIL
From: LENOIL@XX.LCS.MIT.EDU (Robert S. Lenoil)
Newsgroups: comp.protocols.appletalk
Subject: Re: Several questions about LWSRV
Message-ID: <12397021400.41.LENOIL@XX.LCS.MIT.EDU>
Date: 9 May 88 21:12:26 GMT
References: <12394007932.137.A.ERIC@GSB-HOW.Stanford.EDU>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: lenoil%apple.csnet@relay.cs.net
Organization: The Internet
Lines: 31

>Thirdly, we're running MicroSoft Word on MS-DOS systems which are equipped
>with AppleTalk cards and Apple's "AppleShare PC" software (which in fact
>supports printing as well as file servers).  We're seeing constant AppleTalk
>checksum errors when the MS-DOS system tries to send a PostScript file to the
>lwsrv process; here's a sample log entry:
>   Checksum error: Incoming: e969, calculated d017 [1326.27]
>   Dropping packet
>(where 1326.27 is the AppleTalk net.node of the MS-DOS system).  There don't
>seem to be any problems when the DOS system sends directly over AppleTalk to
>the LaserWriter, only when the output is spooled through lwsrv.  Any ideas?

The AppleTalk PC Card had a bug in its ROM which generates incorrect DDP
checksums on certain packets.  An updated ROM (rev C) has been phased into
production.  It was supposed to coincide with the product name change from
AppleTalk PC Card to LocalTalk PC Card, but due to delays, some LocalTalk
PC Cards do have the rev B ROM (part no. 3420007-B).  The reason you do not
see a problem when printing directly to a LaserWriter is because the ATALK
driver only sends a DDP checksum on an ATP response if the request had a
checksum; most Macintoshes and LaserWriters do not use DDP checksums.

You have two options to fix your problem:

1) Change lwsrv to not send DDP checksums.  This will cause the PC card to
   send responses without DDP checksums, thus sidestepping the problem.
2) Upgrade your ROM.  Apple has not yet established an upgrade policy, in
   part because it is not known how many users are affected.  Making your
   situation known to your supplier will help in this regard.

Robert Lenoil
Apple Computer, Inc.
Network Systems Development
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