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Date:      Thu, 4 Jan 1996 10:35:20 -0700 (MST)
From:      Terry Lambert <>
To: (Mark Hittinger)
Subject:   Re: LAT support (fwd)
Message-ID:  <>
In-Reply-To: <> from "Mark Hittinger" at Jan 3, 96 08:53:57 pm

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> Actually the specs for both DECNET, LAT, MAP, DDCMP, etc are fully available.

Not LAT... the wanted to keep multisession proprietary.

> I think there might also be an image for the DECserver-200 that supports 
> TCP/IP in addition to (or rather than) LAT.

Stanford built one if I rememebr correctly.

> In the heyday of VAX/VMS world domination there were a couple of third party
> LAT software systems and third party DECNET implementations.  I remember 
> setting up LAT on an SCO-Xenix system :-) 

All of these were licensed.  I remember setting up the same thing on
an Interactive box (LAT on DECNet as a streams stack).  Might have
been a Touch Communications Inc. product.

> Some of us reverse engineered the protocol using a combination of an
> article that appeared in the Digital Technical Journal and a few header
> files that appeared in older versions of Ultrix.  Later programs were
> donated to DECUS which "sniffed" LAT protocol.  Sources too.

Yep.  The proprietariness has been eroded since the old Interactive days.

> Now that the financial value of these implementations are rather
> grim...I wonder if it might be possible to get one of them into
> the public domain.  I will check with one of the guys I know who
> implemented a portable LAT driver.


> We might wind up with another problem with the FreeBSD ethernet drivers.
> We would then be in a situation where we might have several packet
> drivers needing access to the same ethernet device.


[ ... ]

> VMS handled this better, but you had to start the system in a particular
> order or things would not work.

The problem here is that the Sun DECNet, like the real thing, diddles
the ethernet address based on the DECNet address.  It can do this because
of the LANCE chipset and the associated hardware hacks to allow a write
interface.  Much DECNet hardware (unless you go Phase V, which I'm too
old for) relied on this.  For instance, you can't route DECNet, so you
have to fake the addresses on a bridge.

					Terry Lambert
Any opinions in this posting are my own and not those of my present
or previous employers.

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