bobkil@ibmpcug.UUCP (Bob Kilgore) (08/04/89)
There have been a number of posting's to Kenneth Herron who
apparently had a "simple thin ethernet question". I can't
seem to find the original posting and therefor can't E-Mail
to him directly. I think, Kenneth, you have discovered that
there is no such thing as a 'simple' ethernet question. For
each question you can ask you can get any number of answers.
While simple in concept, Ethernet (8802-3) can be complex
enough to accommodate a wide variety of solutions. Since
the real requirements are fairly loose a number of these
solutions may fall outside the domain of ethernet. The
majority of the responses to your question were correct and
I am sure are viable. Some however imply further
constraints on the system.
One in particular imposes a constraint that may not be
acceptable. That is the response from Frank Rahmani that
suggested the 'glued' cable. Everything was OK until the
suggestion that you use a 'right-corner' piece in the
attachment to the tee. The area of interest in the
standard, 8802-3, is paragraph 10.5.3 the total segment DC
loop resistance shall not exceed 10 ohms. Each in-line
connector pair shall contribute no more than 10 milli-ohms.
In Mr. Rahmani's solution he has placed 2 (?) more mating
pairs at each node. This will reduce your total node count
per segment to about 10 from 30. For small segment node
count a good way to go. If more nodes per segment are
required then you may have to remove the corner connectors.
Yet another possible answer is to use the AUI (transceiver)
cable attachment on you PC interface card and run the coax
inside the walls. You then have the choice of using thin or
thick coax since the user will never see the cable. You
could use any one of the new subminiature MAU's
(transceivers) now beginning to appear on the market. For
example the Fujikura FN 2400 series. Some of these can have
an AUI cable permanently attached. ie: FN2100 series.
My preferred solution, however, is to run fiber-optic cable
now for the new installations, and eliminate the problems
associated with electrical drop and transmission systems.
Good Luck on your Ethernet
bob
bobkil@ipmpcug.co.uk
!uunet!ibmpcug.co.uk!bobkil
--
Automatic Disclaimer:
The views expressed above are those of the author alone and may not
represent the views of the IBM PC User Group.jjgv@gmv.es (Juan Jose Galan) (08/17/89)
I have been following Dave Hill, Frank Rahmani and Bob Kilgore
messages concerning wall connection possibilities for thin ethernet,
as the company I work for is building a new facility including thin
ethernet. None of the presented options seem to be quite nice from the
aesthetic point nor from the maintanability and fail safe use by a lot
of users (in my case, over 100, I have a multiport from Isolan, Vaxes,
Sunes, ATs, ...) I have found a wall plug from a German company called
Telega"rtner plus a 'drop' cable that seems to solve theproblem, but it
is really not low-cost:
the wall plug (ref. T46802200 or EAD, I believe) has a couple of female BNCs
where you plug the thin ethernet, and in the front has two 'propietary-type'
plugs, where you can connect a 'propietary-type' cable (to each one), and
this cable can be connected to the ethernet board on your AT without the
BNC-T (cable ref. EDA).
Principal advantages are:
you can plug or unplug this special cable ethier from your PC or from
the wall outlet without disturbing the net (!?)
you have a nice wall connector and a single nice cable without reducing
your node count
you have a couple of ethernet nodes at hand with only one wall
outlet maintenance is lowered
no closing the net cables are required when nothing is plugged cables
are available in 2, 2.5, 3 and 5 meters lenth
you can even mount power supply in the same wall outlet (interesting
in case of protected supply)
all those advantages are claimed by the vendors, I have no more information
than that. Amongst disadvantages, I know by the moment but one: price! Wall
outlet isaroung 7500ptas (or 120DM aprox); cable is aroud 7500ptas
(or 120DM aprox); cable is around 8000 to 10000ptas (or 127 to 160DM).
I have a couple of questions:
1.- Has somebody used this or knows of someone that has? What can be
said about advantages and disadvantages?
2.- Can someone provide me some more hints on the subminiature MAUs (trans-
ceivers) such as aprox cost, limitations, number of them per segment,
are they active (I suppose yes), is it possible to connect them to the
normal ATs ethernet cards (via BNC?) like 3Com ones (I suppose not), ...
As I am not usually following the news, I would appreciate if apart from
the usual news answers a direct e-mail message to me could be sent. My
address is
cbachmaier@gmv.es (Carlos Bachmaier), or you can also try:
within Europe: cbachmaier%gmv.es@mcvax.uucp
or mcvax!gmv.es!cbachmaier
within USA: mcvax!gmv.es!cbachmaier@uunet.uu.net
or uunet!mcvax!gmv.es!cbachmaier
Carlos Bachmaier
GMV, Cristobal Bordiu 35, E-28003, Madrid, Spain
Disclaimer: I have not shares on Telega"rtner not do I receive any fee for
this. Furthermore, the information hereto provided has been gathered from
comercial propaganda and interviews with vendors, so there could be
inaccuracies, misunderstandings, ...
Even more, as you can see from my message, I am not an expert myself on all
this matters, but the expert is on holidays and the building is going on ...
Deliverytime: 9th November!
In any case, I think this solution seems promising, althougt perhaps to
costly!
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