[comp.dcom.lans] 10BaseT wiring question #4936

keith@sequoia.UUCP (Keith Pyle) (04/24/91)

Disclaimer: this just became an issue here, so if this question has been
answered already, my apologies.

Is it possible (and/or practical) to have more than one device (workstation,
PC, etc.) per port using 10BaseT?  We have a number of developers with two
and sometimes three systems connected to the thinnet in their offices.  We
are considering relocation and 10BaseT has some desirable qualities, plus
lower cost than thinnet.  However, if we can't have multiple devices per
10BaseT port, it won't likely be practical for us.  Providing multiple ports
per office isn't likely to be accepted.

Thanks.
-- 
-----------------------------------------------------------------------------
Keith Pyle                                UUCP: ...!cs.utexas.edu!execu!keith
Comshare, Inc., Austin, Texas             Internet: keith@execu.com
"It's 10 o'clock.  Do you know where      Disclaimer: Everything I say is
   your child processes are?"               true unless I use the word 'the'.
-----------------------------------------------------------------------------

haas%basset.utah.edu@cs.utah.edu (Walt Haas) (04/24/91)

In article <35817@sequoia.UUCP> keith@sequoia.UUCP (Keith Pyle) writes:
>Is it possible (and/or practical) to have more than one device (workstation,
>PC, etc.) per port using 10BaseT?  We have a number of developers with two
>and sometimes three systems connected to the thinnet in their offices.  We
>are considering relocation and 10BaseT has some desirable qualities, plus
>lower cost than thinnet.  However, if we can't have multiple devices per
>10BaseT port, it won't likely be practical for us.  Providing multiple ports
>per office isn't likely to be accepted.

A strategy we recently used in one building was to install a number of RJ45s
in each office with wiring back to the closet where the hub is.  Since this
was done when the building was being constructed the economics were pretty
favorable.  We only plug the closet end of the wire into actual hub
electronics when somebody wants to use the corresponding RJ45 in the office.

Another approach would be to keep a selection of multiport UTP transceivers
handy.  TCL makes UTP transceivers that have 1, 2 or 4 AUI connectors to
supply that number of hosts.  I haven't actually tried this approach myself
but it sounds reasonable :-).

-- Walt

arnold@synopsys.com (Arnold de Leon) (04/25/91)

In article <35817@sequoia.UUCP> keith@sequoia.UUCP (Keith Pyle) writes:
>Disclaimer: this just became an issue here, so if this question has been
>answered already, my apologies.
>
>Is it possible (and/or practical) to have more than one device (workstation,
>PC, etc.) per port using 10BaseT?  


	o attach a multi port transceiver to your 10 base T transceiver
	  
	o buy a 10 base T transceiver with multiple ports (essentially
	  above in one box).  MiLan makes one.

	o buy some of those media converters that convert 10 base T
	  to thinnet.  Cabletron, MiLan and ODS make these I believe.
	

>  Providing multiple ports
>per office isn't likely to be accepted.
>

If you are doing a new installation it should not be hard to provide the
capability for 2 drops per office.  We pulled 4 pair for 10 base T and
fanned it out to 2 jacks (E1 and E2).  E1 is on panels on our IDF's and E2
is just terminated on blocks.  This allowed us to give each office 2 drops
connections without going to any of the previous schemes.

>-----------------------------------------------------------------------------
>Keith Pyle                                UUCP: ...!cs.utexas.edu!execu!keith
>Comshare, Inc., Austin, Texas             Internet: keith@execu.com


-- 
Arnold de Leon  			arnold@synopsys.com
Synopsys Inc.				(415) 694-4183
700 E. Middlefield Road
Mtn. View, CA 94043-4033

dan@gacvx2.gac.edu (04/25/91)

In article <35817@sequoia.UUCP>, keith@sequoia.UUCP (Keith Pyle) writes:
> Disclaimer: this just became an issue here, so if this question has been
> answered already, my apologies.
> 
> Is it possible (and/or practical) to have more than one device (workstation,
> PC, etc.) per port using 10BaseT?  We have a number of developers with two
> and sometimes three systems connected to the thinnet in their offices.  We
> are considering relocation and 10BaseT has some desirable qualities, plus
> lower cost than thinnet.  However, if we can't have multiple devices per
> 10BaseT port, it won't likely be practical for us.  Providing multiple ports
> per office isn't likely to be accepted.

It is not possible to run multiple computers off of a 10BaseT port, just by
putting in a TEE or daisy chaining computers.  It is possible to install a
10BaseT to thin net converter that would provide a BNC connector on the wall,
but still allow the use of UTP wiring in the wall.  Another possibility would
be to provide a single UTP connection and configure the rest of the network so
that the repeater budget allows connecting a work group hub to the single
connection and gives 11 ports for connecting 10BaseT equipment.  I use this in
classrooms and have a hub I can loan to faculty needing this.  I might need to
do this in my office as well.  A third possibility would be to use multi media
hub equipment that allows a mixture of 10BaseT, thin net, and AUI connectors
just by installing the appropriate card in the hub.  Then run the appropriate
cable type the offices that need it.  Using a multi-port thin net cart is is
possible to maintain the star configuration of the network, but with out doing
away with daisy chaining.  We install two four pair wires on each wall of an
office in a new construction.  We provide a 20 foot cord to the owner of the
office.  We have also wired buildings and departments with a single daisy
chained thin net.  They work too, but I have found that the majority of the
problems are caused in the spring when it comes time to clean office and both
BNC connectors are disconnected "just a little while" while the desk and other
office contents are being moved is being moved.  I could live with it, but the
other users still get the pot of boiling oil out for me.

-- 
Dan Boehlke                    Internet:  dan@gac.edu
Campus Network Manager         BITNET:    dan@gacvax1.bitnet
Gustavus Adolphus College
St. Peter, MN 56082 USA        Phone:     (507)933-7596

braun@dri.com (Kral) (04/26/91)

In article <35817@sequoia.UUCP> keith@sequoia.UUCP (Keith Pyle) writes:
>Disclaimer: this just became an issue here, so if this question has been
>answered already, my apologies.
>
>Is it possible (and/or practical) to have more than one device (workstation,
>PC, etc.) per port using 10BaseT?

I know that Cabletron had a TP to Thinnet box which allowed you to string up to
10 stations off of one TP port.


-- 
kral * 408/647-6112 *               ...!uunet!drivax!braun * braun@dri.com
Whoever is calm and sensible
	is insane
		-- Rumi

andrew@jhereg.osa.com (Andrew C. Esh) (04/27/91)

In article <35817@sequoia.UUCP> keith@sequoia.UUCP (Keith Pyle) writes:
>Disclaimer: this just became an issue here, so if this question has been
>answered already, my apologies.
>
>Is it possible (and/or practical) to have more than one device (workstation,
>PC, etc.) per port using 10BaseT?  We have a number of developers with two
>and sometimes three systems connected to the thinnet in their offices.  We
>are considering relocation and 10BaseT has some desirable qualities, plus
>lower cost than thinnet.  However, if we can't have multiple devices per
>10BaseT port, it won't likely be practical for us.  Providing multiple ports
>per office isn't likely to be accepted.
>
>Thanks.
>-- 
>-----------------------------------------------------------------------------
>Keith Pyle                                UUCP: ...!cs.utexas.edu!execu!keith
>Comshare, Inc., Austin, Texas             Internet: keith@execu.com
>"It's 10 o'clock.  Do you know where      Disclaimer: Everything I say is
>   your child processes are?"               true unless I use the word 'the'.
>-----------------------------------------------------------------------------

It sounds like you want to put all these three computer Thin segments on a
port each, and tie them all together with a 10baseT hub.

No problem. Leave the Thin segments set up the way they are, and add an AUI
to ThinNet transceiver to the segment. We have a Cabletron ST-500, but a
Allied Telesis CentreCom MX-10 works just as well. On the AUI side, put a
ODS 264 Twisted Pair Tranceiver. It is powered by a small AC power supply,
so you don't have to worry about where the power is going to come from. The
other end of the 264 is Twisted Pair, which goes into your hub. All three
machines on the Thin segment look like they are on the same port, from the
hub's point of view. We run it, and it works just fine, except that if you
screw around with the ThinNet, like take off one of the terminators or
short it or something, the 264 locks up and has to be powered off-on to get
it to talk to the ST-500 again. Have fun.

-- 
Andrew C. Esh			andrew@osa.com
Open Systems Architects, Inc.
Mpls, MN 55416-1528		Punch down, turn around, do a little crimpin'
(612) 525-0000			Punch down, turn around, plug it in and go ...

nieland_t@kahuna.asd-yf.wpafb.af.mil (04/28/91)

In article <1991Apr26.203628.3479@jhereg.osa.com>, andrew@jhereg.osa.com (Andrew C. Esh) writes:
> In article <35817@sequoia.UUCP> keith@sequoia.UUCP (Keith Pyle) writes:
>    [portion deleted]
> No problem. Leave the Thin segments set up the way they are, and add an AUI
> to ThinNet transceiver to the segment. We have a Cabletron ST-500, but a
> Allied Telesis CentreCom MX-10 works just as well. On the AUI side, put a
> ODS 264 Twisted Pair Tranceiver. It is powered by a small AC power supply,
> so you don't have to worry about where the power is going to come from. The
> other end of the 264 is Twisted Pair, which goes into your hub. All three
> machines on the Thin segment look like they are on the same port, from the
> hub's point of view. We run it, and it works just fine, except that if you
> screw around with the ThinNet, like take off one of the terminators or
> short it or something, the 264 locks up and has to be powered off-on to get
> it to talk to the ST-500 again. Have fun.
> 

Why not use a MILAN 10BaseT to 10Base2 box (called Alternet) instead.  It 
allows up to 10 10Base2 devices off the coax.

Ted Nieland				nieland_t@kahuna.asd-yf.wpafb.af.mil
Control Data Corporation		nieland@dayfac.cdc.com
(513) 427-6355				ted@nieland.dayton.oh.us