[comp.dcom.modems] Using a Micom with multiple systems for indial/outdial

dewey@sequoia.UUCP (Dewey Henize) (07/15/89)

Some time ago, I asked the collective net.knowledge if anyone had had any
experience connecting various modems through a Micom Instanet port selector
and allowing sharing of these modems by multiple machines for both indial
and outdial.

First, let me thank all the folks that responded:
 
<conspicuously empty list>

Seriously, I understand that this wasn't a particularly simple thing to ask
help for, and probably no one else had fought this configuration before.
Since I have since managed to get it working, though, I thought that if
someone else DID need to do this they might like to avoid the pitfalls I
found.  If you aren't interested, hit 'n' or whatever skips for you now.


First, I found that an unusual variant of a null modem cable was required
to connect the modem to the Micom.  It looks like this:


	 2 -------------------- 3
	 3 -------------------- 2
	 4 -------------------- 5
	 5 -------------------- 4
	 6 --------------------20
	 7 -------------------- 7
	 8 --------------------11
	11 -------------------- 8
	20 -------------------- 6
	22 --------------------25
	25 --------------------22

The contact person at Micom that seems to know what he is really talking
about is Fima Visman.  He not only was able to discuss the above cable
configuration, but he went into a very informative walkthrough of just
what is going on during the connect process.

Next, the micom port that this cable connects to needs to be set with the
special protocol group, 6.  This is the auto-answer/dialout group.

Depending on the various modem speeds you wish to support, define one or
more symbolic resource classes and destination groups for these ports.  If
you were only using telebits, for example, you might just choose a group
named telebit.  For these ports, assign appropriate autobaud groups and
access groups.

With our sequent, we had a choice of either incoming or outgoing for each
serial port.  I defined a few of them at outgoing and connected them to
the micom with normal terminal configurations and a short idle timeout.
The rest of our serial lines were connected to the micom in the 'normal'
mode, ie DTR ports.  The DTR ports were given the usual style of symbolic
names, with primary, secondary, and tertiary destination groups to allow
for varying initial connect speeds.  Although not strictly necessary, this
was also the strategy I used for our sun (that allowed bidirectional serial
port use).

Now calls that come in through the modem go first into the Micom, where we
can require a resource password (site password) before passing on to the
various machines.  These lines have a default group destination, so while
a knowledgable user can select what machine to attempt to connect with, a
simple return allows connection to a preferred system.  At this point,
normal login procedures apply.

For dialout, any machine with an outgoing serial line to the micom can use
it and recieve the micom resource prompt.  Selecting 'telebit' (or other
class for lower speed modems) takes it to the first available modem of that
class, and then the uucico chat script can navigate through the dialout
and remote connect procedure.

Just a FYI note.  Contact me if you need further details.  I know there are
a lot of various flavors of Micoms out there, hopefully this will be of help
to someone (like me) that needs to share out some of their resources amoung
multiple machines.

Dewey

-- 
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| ...!cs.utexas.edu!execu!dewey or | "If you will just quit shouting at me, I |
|   ...!natinst!sequoia!dewey      | will try to hear what you are saying"    |
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|   If I so often disagree with my company, of course these ideas are mine    |
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