[comp.dcom.lans] A question about ethernet boards with thinwire and transceiver outputs

jeff@drexel.Drexel.edu (Jeff White) (07/13/87)

  I have a question about computers or ethernet boards that have both
thinwire (BNC connector) and transceiver (DB-15 conn.) outputs (independent
of manufacturer).  With one of these boards, are both outputs active at
the same time?   For example, suppose you are using the transceiver output,
with a transceiver attached to a thick wire ethernet cable (typical of
most installations).  What happens if you now attach 1 or more stations
to the same interface board using the thinwire output.  Will this 'master'
station be able to talk to all the stations on both the thinwire and
thickwire cables?  Will all the stations appear to be located on 1 common
backbone cable, or will the stations on the thinwire and thickwire be isolated
from one another?  If they are isolated, can the 'master' (common) station
act as a gateway?  Originally, I just assumed that for some reason both
outputs wouldn't be usable at the same time.  However, after thinking about
it for a while, it seems to me that if there isn't any type of switch which
specifically selects one output, that both should be functional at the same
time.  
   If replies are via email and I get a definitive answer, I'll summarize
the findings to the net.


						Jeff White
						Drexel University - ECE Dept.
						seismo!presby!drexel!jeff

ron@topaz.rutgers.edu (Ron Natalie) (07/14/87)

At least on the Sun 3/50's you have to choose.  You do this by means of
eight dipswitches on the CPU board.

-Ron

jerry@oliveb.UUCP (Jerry F Aguirre) (07/14/87)

I can only speak from limited experience but, no, both outputs are not
active at the same time.  There is a jumper on the board to select which
interface is active.

If you want to connect a thin ethernet to a thick ethernet then there
are two ways.  The first is to buy a simple BNC to N adapter and plug
the cables togther.  The restrictions on length and number of
connections have to be followed of course.

The second is to use a box to connect them.  The simplest is a repeater.
Lots of people make them and there are also multi-port repeaters that
can connect several ethernet segments together.  More sophisticated
boxes can handle routing and isolate traffic.