From: harvey@indyvax.iupui.edu
Newsgroups: comp.sys.novell
Subject: Re: HELP: I want to access a DECNET host through a v3.11 Server
Date: 22 Dec 92 16:03:58 -0500
Organization: Indiana University-Purdue University at Indianapolis

In article <BznDIx.7C0@world.std.com>, dlowe@world.std.com (Miller Lowe) writes:
> In our office we have Three Netware Servers, A couple
> of VAX and tens of PCs.  We want to connect the PCs to the VAX
> systems using a LAT terminal emulator such as SmartTerm 340.
>
> Here is the current cabeling picture;
>
>    /-----\          /-----\                     /-----\
>    | VAX |          |MICRO|                     |MICRO|
>    |     |12.1      | VAX | 12.2                | VAX | 12.3
>    \--+--/          \--+--/                     \--+--/
>       |                |         LAN 'A'           |
>   ----+-------+--------+---------------------+-----+--------
>               |                  DECNET      |
>               |                          /---+---\
>            /--+---------\                | PC #1 |
>            | PC Running |                \-------/
>            | PCBRIDGE   |
>            \-------+----/
>                    |             LAN 'B'  IPX, TCP/IP & DECNET
>   <-------+--------+------------------------+----------------->
>           |                                 |IPX = FEEDBFOO
>       /---+---\                       /-----+------\
>       | PC #2 |                       |  NetWare   |
>       \-------/                       |v3.11 Server| "MOTHRA"
>                                       \-----+------/
>                   IPX & TCP/IP              | IPX = FEEDBOFF
>    <-----------+----------------------------+------------------>
>                |           LAN 'C'                     Other Netware
>            /---+---\                                   Servers  -->
>            | PC #3 |                                   & LANs
>            \-------/
>
> I have connected PC #1 and logged into the NetWare Server MOTHRA
> with no problem and according to the terminal program (which has a
> LAT driver) documentatiom I should have no problem logging onto the
> VAX systems from PC#1 or PC#2.  I haven't installed the terminal
> program yet.
>
> BIG QUESTION #1:
> ----------------
> How do I get PC #3 to process DECNET packets through the NetWare
> server MOTHRA.  While MOTHRA will pass TCP/IP or IPX I do not think
> that it will pass DECNET even though it uses 802.3 Ethernet.
>
> Must I put some sort of router attaching LAN 'B' and LAN 'C' that will
> route DECNET packets and keep the LANs withe their respective IPX names?
> I have put a PCbridge between them but as expected I get Router errors
> off of the MOTHRA internal router.

First, why are you talking about DECnet all of the sudden?  DECnet is not
LAT, LAT is not DECnet.  LAT is a datalink layer protocol.  It cannot be
routed by a network-layer router, but it can be passed by a datalink-layer
bridge.  If you buy LAT terminal servers from DEC, they can booted from
VMS hosts using DECnet.  But that does not apply here in this case, and
has nothing to do with LAT anyway.

I haven't used PCbridge, but most bridges can be configured to only bridge
certain datalink layer protocols.  Since MOTHRA is routing IPX and IP, if
you put a bridge between LAN C and LAN B, you should configure it to bridge
LAT only.  Bridging the protocols MOTHRA is already routing between it's
interfaces will indeed cause severe problems, as you have already observed.

Off to the right you show more NetWare servers and LANs.  If your network
is very extensive, you probably don't really want to bridge LAT everywhere
if you can avoid it.  You might want to think about using Telnet instead.
If Telnet overhead on the VAXes is an issue, or you cannot get/afford a
TCP/IP package for your VAXes, you could instead buy a Telnet/LAT terminal
server and stick it on LAN A.  Users could Telnet to the terminal server,
then connect to the VAXes from there using LAT.  Since the terminal server
is on LAN A, LAT traffic is limited to LAN A, so you don't have to bridge
it anywhere.  Since all your routers already handle IP, any of your PCs
can reach the terminal server by Telnet.  And since the terminal server
concentrates the terminal session traffic with LAT, the VAXes avoid the
high interrupt stack and kernel mode time overhead that Telnet can cause.

>[deleted...]
--
James Harvey    IUPUI OIT Technical Support/Networks
harvey@iupui.edu  harvey@indiana.edu  uucp:iugate!harvey  bitnet:harvey@indyvax