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From: jbvb@VAX.FTP.COM (James Van Bokkelen)
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Re: LAN Manager (was PC/NOSs)
Message-ID: <8909271548.AA05302@vax.ftp.com>
Date: 27 Sep 89 15:48:16 GMT
References: <8909261939.aa15775@Obelix.TWG.COM>
Sender: daemon@ucbvax.BERKELEY.EDU
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One major problem with LAN Manager is that its only programming
interfaces are the "Named Pipes" and Netbios NCB interfaces.  There is
no defined method of getting at an unadulterated transport protocol
connection; whether the transport is XNS or TCP or OSI the lowest you
can get is a Netbios session.  So the LAN Manager "standard" can't
talk to anything except other LAN Managers or Netbioses without vendor
extensions (which won't be standard unless/until the market produces
one).

Furthermore, there is no defined interface to the redirector, so any
filesystem sharing you do uses SMB.  No Netware, NFS, RFS or RVD under
LAN Manager, unless you want to hide a kludge that translates SMB to
another protocol below the pseudo-NETBIOS layer (not if I can avoid it).

In terms of layering, NETBIOS is more or less session-layer by itself.
It can be defined to use different transport layers (TCP, XNS, OSI,
DECNet, etc).  Transport layers can use different MAC layers, but it
is hard to make a particular instance of a transport layer independent
of the MAC layer below it; Ethernet uses ARP one way, 802.5 uses it
another, MTUs and headers differ, bit orderings differ.  Neither NDIS,
ASI, Packet Driver or OLI provide real MAC-layer independence; instead
they provide demux support and independence from details of individual
Ethernet (or whatever) cards.  IBM's ASI interface is very
802.5-specific, but the others aren't specific to one MAC layer.

Fundamentally, LANManager is Microsoft's idea of what a NOS should
look like, complete with solutions for all the problems they felt were
important, tailored for the operating systems they care about.  As
such it is different from SNA/SAA (IBM's idea), DECNet (DEC's idea),
Netware (Novell's idea), etc. etc., but no less proprietary and
narrowly-focussed.  The open standard you would probably prefer
doesn't really exist yet, but Apollo/HP (with NCS), Sun (with their
RPC and Yellow Pages) and the OSI people are all heading that way.

James B. VanBokkelen		26 Princess St., Wakefield, MA  01880
FTP Software Inc.		voice: (617) 246-0900  fax: (617) 246-0901