AUI <-> AUI cabling question

AUI <-> AUI cabling question

Post by Matthew Det » Thu, 07 Oct 1993 01:53:28



So, I've got this PC sitting right next to my workstation, and I want
to connect them via ethernet.  One card has an AUI output free (the
BNC connector is in use) and the other has an AUI and a 10baseT
connector free.  I have been using two transceivers to go from AUI to
AUI, with thinnet in between.

However, I don't get to keep the transceivers forever.  I am wondering
if it is possible to wire the AUI ports together.

I was planning to connect the cable as follows:

AUI-1       AUI-2
pin#        pin#
----        ----
 3 DO+       5 DI+
 4 SHIELD    4 SHIELD
 5 DI+       3 DO+
10 DO-      12 DI-
11 SHIELD   11 SHIELD
12 DI-      10 DO-

Obviously I don't want to connect the Voltage Plus (pin 13) since I
don't want to cook my network card.

Do I need to connect the Voltage Shield (pin 14) straight thru?
Do I need to connect the Voltage Common (pin 6) straight thru?
Are these used ONLY for the power supply functions?  If so, I don't
need them, right?

Obviously pins 7, 8, & 15 are no connects.

I am not sure what to do with Control-In lines (pins 1, 2, & 9).  Are
these used by the transceiver to send messages to the AUI?  (one way)

It occurs to me that if these signals are generated by the
transceiver, and if they are REQUIRED, my idea might not be workable.

Any comment and advice is appreciated.  I do not know a great deal
about the Ethernet spec, and I am working off my knowledge of how
RS232 signals are cross wired.  I realize this may be a Bad Idea.
(that's why I'm posting!)

Thanks.

--
$ Matthew Deter                       |  "In a capitalist society, all human


 
 
 

AUI <-> AUI cabling question

Post by Henry Spenc » Fri, 08 Oct 1993 02:30:37



>However, I don't get to keep the transceivers forever.  I am wondering
>if it is possible to wire the AUI ports together.

It sort of works, but only sort of.  The AUI interface is *not* symmetrical;
to join two of them together reliably, you must have electronics in between.
Just a cable won't do.  But it does sort-of-kind-of work when the phase of
the Moon is right.

Quote:>I am not sure what to do with Control-In lines (pins 1, 2, & 9).  Are
>these used by the transceiver to send messages to the AUI?  (one way)

Yes.  This is the problem area -- collision detection won't work without
electronics in between the two AUI ports.
--



 
 
 

AUI <-> AUI cabling question

Post by Mark Champi » Sun, 10 Oct 1993 10:43:47


: So, I've got this PC sitting right next to my workstation, and I want
: to connect them via ethernet.  One card has an AUI output free (the
: BNC connector is in use) and the other has an AUI and a 10baseT
: connector free.  I have been using two transceivers to go from AUI to
: AUI, with thinnet in between.
:
I'm not sure I understand this correctly, but it sounds like you want
to connect the BNC (10base2) to one network and the AUI port to another.
This won't work unless you have a special ethernet board designed with
two ethernet interfaces in it.  The same is true for your board with
the AUI/thin/TP connections - you can only use one at a time.

Also, although I have never tried it, I think you need the collision
detect electronics which would be in the transceiver electonics (the
part you are eliminating).  This detects collisions and hammers the
ethernet to be certain that all nodes on the network detect the collision.

Mark Champion                    | Northwest Digital Systems
UUCP: uunet!nds!mark             | Voice: 206-524-0014

 
 
 

AUI <-> AUI cabling question

Post by Mark Reard » Thu, 14 Oct 1993 22:01:05



|> : So, I've got this PC sitting right next to my workstation, and I want
|> : to connect them via ethernet.  One card has an AUI output free (the
|> : BNC connector is in use) and the other has an AUI and a 10baseT
|> : connector free.  I have been using two transceivers to go from AUI to
|> : AUI, with thinnet in between.
|> :
|> I'm not sure I understand this correctly, but it sounds like you want
|> to connect the BNC (10base2) to one network and the AUI port to another.
|> This won't work unless you have a special ethernet board designed with
|> two ethernet interfaces in it.  The same is true for your board with
|> the AUI/thin/TP connections - you can only use one at a time.

That was my impression too and yes, only one physical port can be
used at a time unless the card is actually a repeater internally.

|>
|> Also, although I have never tried it, I think you need the collision
|> detect electronics which would be in the transceiver electonics (the
|> part you are eliminating).  This detects collisions and hammers the
|> ethernet to be certain that all nodes on the network detect the collision.

The cheapest way would be to purchase a 10BaseT tranceiver for the AUI
port of the AUI and 10Base2 board and then use a cross over cable to the
other boards 10BaseT port.  Connecting the AUI's together requires a two
port (or more) tranveiver block which will cost more.

--
_____________________________________________
Mark Reardon   AT&T Tridom   (404-514-3383)

 
 
 

1. AUI <-> AUI cable ?

I've got two machines, one with 15-pin (AUI, right?) and BNC, and one with
only a 15-pin connector.  Rather than buying an xceiver for the one
machine so I can use thinnet, is it possible to make a "null" cable to
connect the two 15-pin ports?  

--

Custom UNIX software and networking solutions.
All statements contained herein are probably accurate.

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