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From: alistair@microsoft.UUCP (Alistair BANKS)
Newsgroups: comp.dcom.lans,comp.os.os2.misc
Subject: Re: Lanmanager and 2 or more cards.
Message-ID: <56251@microsoft.UUCP>
Date: 1 Aug 90 22:54:30 GMT
References: <japi811g3@tmsoft.uucp> <56187@microsoft.UUCP>
Reply-To: alistair@microsoft.UUCP (Alistair BANKS)
Organization: Microsoft Corp., Redmond WA
Lines: 55

In article <56187@microsoft.UUCP> alistair@microsoft.UUCP (Alistair BANKS) writes:
>In article <japi811g3@tmsoft.uucp> mshiels@tmsoft.UUCP (Michael A. Shiels) writes:
>>Can one lan manager server with 2 or more cards work as a bridge between
...
>It is theoretically possible to write a software-only bridge that would
>reside in a LanMan server and use the same NDIS drivers, but Microsoft
>has no plans to do this at present.

I received more flames than usual about LanMan internal bridging
as part of the LanMan product, so I'm posting some extra thoughts.

LAN Manager networks can be connected today by a number of
3rd party products at the BRIDGE and ROUTER level.

Microsoft's own world wide LAN is a good example of this:
our international subsiduaries and field offices are connected to
the campus net using leased telephone lines with bridges
and routers from Ungerman Bass.  These devices contain both hardware
and software, and they connect directly to the LAN cable.

Routers (and most bridges) do provide effective network
traffic isolation, yet give good performance (line speeds
up to T3/20 Mbps);  the technology is mature and fairly
inexpensive.

The disadvantage of briges and routers is that they are
topology and protocol dependent;  Microsoft's internal net relies
on the fact that all locations are wired with Ethernet and that the
protocol used when crossing routers is XNS.  Leased lines
can also be costly if the remote connections are needed only
occasionally.

Note that not all protocols support routing which is the
more effective way to isolate LAN traffic.  Netbeui which
ships with LM 2.0 supports routing only on Token Ring;
but note that Novell's IPX/SPX or 3Com's NBP do not support
source level routing at all.

The problems with bridges and routers can be solved in a
general way only with a transport level gateway and that is
our approach at present.

Microsoft LanManager is a network built on an open transport
interface - thus bridging & routing is left as a feature of 
the transport - so LanMan on TCP/IP would use TCP/IP routers,
LanMan on XNS would use XNS routing.

So there are many, open, solutions for LanMan, but what doesnt
exist today is a Microsoft product, which lives on the Lan
Manager server, which does brindging and/or routing. But then
this doesnt exist for our major competitors either.

Alistair Banks
OS/2 Group
Microsoft