Xref: utzoo comp.protocols.tcp-ip:13837 comp.sys.dec:4565
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!uakari.primate.wisc.edu!unmvax!nmt.edu!nraoaoc
From: rmilner@zia.aoc.nrao.edu (Ruth Milner)
Newsgroups: comp.protocols.tcp-ip,comp.sys.dec
Subject: Re: DECnet encapsulation in TCP-IP
Message-ID: <1990Nov20.212552.2536@nmt.edu>
Date: 20 Nov 90 21:25:52 GMT
References: <90313.134117JHL1@psuvm.psu.edu> <15782@cbmvax.commodore.com> <897@fred.UUCP>
Sender: rmilner@zia.aoc.nrao.edu (Ruth Milner)
Reply-To: rmilner@zia.aoc.nrao.edu (Ruth Milner)
Organization: National Radio Astronomy Observatory, Socorro NM
Lines: 39

In article <897@fred.UUCP> rbraun@fred.UUCP (Richard Braun) writes:
>grr@cbmvax.commodore.com (George Robbins) writes:
>>In article <90313.134117JHL1@psuvm.psu.edu> JHL1@psuvm.psu.edu writes:
>>> We're interested in encapsulating DECnet within a TCP-IP package.  We
>>> are looking primarily for a software solution...
>>
>>I believe TGV multinet can handle this...
>
>MultiNet is, IMHO, far and away the best TCP/IP package available for
>VAX/VMS.  
>
>But I fail to understand the original question:  "encapsulating DECnet
>within TCP/IP".  That just doesn't mean anything.  
>
[...]
>What's the need, anyway?  

Encapsulated DECnet is DECnet packets wrapped inside IP packets. To IP-only 
systems, the packets appear as normal TCP/IP and are routed accordingly. When 
they arrive at the destination (running MultiNet), the software strips off the
TCP/IP stuff, finds a DECnet packet inside, and hands it off to DECnet for
the real processing. As far as DECnet is concerned, a DECnet packet just came
off the net.

DECnet is very picky about nodes being "adjacent", i.e. directly reachable
through some line or another. Under normal circumstances you would have to 
have DECnet nodes every step of the way to reach a remote system.  With 
DECnet-over-IP, however, the IP-only node(s) in between are transparent
to DECnet, and even though the two nodes could be miles apart, they appear
to be adjacent. This can *enormously* simply configuring a wide-area DECnet,
especially if there are existing links which only run TCP/IP. It also reduces
the number of systems which must run DECnet; since most UNIX implementations
(at least as of a year ago) cannot do routing between networks, encapsulating 
DECnet within IP can save your hide if you find you need to talk to some 
(DECnet) system a few UNIX routers/gateways away.
-- 
Ruth Milner
Systems Manager                     NRAO/VLA                    Socorro NM
                            rmilner@zia.aoc.nrao.edu