From: BIG-REQ@SUVM.BITNET
Newsgroups: bit.listserv.big-lan
Subject: BIG-LAN Digest, Volume 4, Number 66, Friday, October 9, 1992
Date: 9 Oct 92 21:10:09 GMT
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU

BIG-LAN DIGEST            Friday, 9 October 1992       Volume 4 : Issue 66

Today's Topics:

                         wiring for 10baseT/CDDI
   Wang OPEN/image, Interoperability & Network Integration at Networld
                        NetWare/VINES Integration

Moderated by John Wobus, Syracuse University

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Date: Wed, 7 Oct 1992 17:21:52 +1000
From: Danny Thomas <vthrc@mailbox.uq.oz.au>
Subject:      wiring for 10baseT/CDDI

Hello John, it looks like I just missed out on the latest issue. This is
also being posted to comp.dcom.lans to catch a wider group of people and
hope that doesn't conflict with the intended use of BIG-LAN. For example, I
don't normally follow those news groups cause they expire fairly quickly
from the newshost I use and normally isn't an area I have deep interest in.

Hello people,
             we're just in the middle of designing the cabling of a new
(small) building wing. A fibre link bridged from our current net will be
the entry point. While all equipment shifting to the new wing has AUI/coax
interfaces and thinwire is the primary cabling for the short-term, the
question is in laying out UTP for 10baseT with the possibility of using it
for faster services in the longer term, eg CDDI or whatever becomes
popular. If we were really committed to a faster network, we would have run
fibre as well, but given budgetary constraints it seemed better spending a
rather small increment on the UTP which at least will produce a
higher-quality 10baseT net that will definitely be used in the medium term.
    I guess there aren't many people yet with real-world experience at
laying out CDDI and as should become obvious, I'm operating from a position
of real ignorance so would be grateful of any comments and pointers to
documents that may be of assistance (preferably FTPable).
    The plan is to use Belden 1583A level 5 UTP. The only locally available
RJ45's rated to 100M are Suttle 110. There will be twin runs from each
office's dual RJ45 panel direct to RJ45s in patch panel. The longest run is
33m (100' for the non-metric countries, last I heard Yemen/USA 8-)) with
only 2 connectors (plus 2 more on the interfaces) so it is well within the
10baseT budget.
    I'm worried about crosstalk/interaction between the cable runs along
with noise pickup from parallel mains cables in adjacent cable trays (6"
apart, though with a grounded metal tray between). The longest run close to
mains would be around 12m (40').
    The easiest way of taking cables from one side of the building to the
other is through a 40mm (1.5") conduit - but is it a good thing running ten
cables so close together for 13m? Even for 10baseT, let alone CDDI?
Parallel cables would bunch up as they approach this one conduit too.
    As a means of identification the pair of cables from each office are
run in opposite directions, but I'm not sure whether that will have any
effect on crosstalk between them. When there are several cables running in
a tray, is it a good idea to randomly redistribute along the length of the
run, ie not having the same cables close together for the whole length?
    My guess is that higher quality UTP offers tighter and more consistant
twisting to maximize crosstalk between the pairs at different twist rates,
more uniform and perhaps lower impedance. Something I wonder about though,
is the effect on impedance when the cable comes off the grounded cable tray
(which it is intimately tied down to) into a longish run through plastic
conduit. Presumably that would represent a reasonable impedance
discontinuity that might be quite significant for the sharper edges of
CDDI, even if they are shaped as nicely as posssible.

In terms of 10baseT, a quick perusal of back issues of the BIG-LAN mailing
list showed some different experiences in regard to interference from
adjacent mains. In this part of the world we use 240V AC so presumably the
smaller current flows result in less magnetic interaction?

FROM ISSUE #57
>From: Robert Lummis <rcl@aecom.yu.edu>
>Subject:      Re: 10Base-T Noise and Crosstalk
>
>I've wired a whole (small) campus recently and worried a lot about
>10Base-T noise immunity but I have not had a single problem in that
>regard.  In an experiment at the beginning of installation we jury-rigged
>to most noise-inducing awful mess of wiring we could think of using the
>cable designated for standard wiring and actual electronics at both ends.
>We ran up 12 stories though the 55-foot diameter utility shaft of a
>large research building and intentionally draped the wire over and around
>electrical equipment -- DC elevator motors, compressors, DC relay panel,
>flourescent lights, some magnetic resonance equipment, etc. etc.  Anything
>that anybody could think of that might cause trouble we wrapped or draped with
>the cable.  We tested it over several days with actual ethernet traffic
>and also with a Hewlett Packard 10BAse-T cable tester.  The result: not a
>single incident of noise interference.  (tested in various ways with a
>sniffer, the HP cable tester, and a Lanalyzer)  Mind you-- this is new
>AT&T 10Base-T cable, not in-place telephone wiring.

and from Bruce Nielsen (Nielsen@act-act4-po.act.org)
>  In my opinion (and experience) the unshielded twisted pair (UTP) LAN
>  cable running alongside the power cable will likely cause you problems.
>  I'm not certain about the crosstalk, but the signal-to-noise ratio (SNR)
>  is possibly where you'll have problems.  In any event, I always require
>  our contractors to "certify" the cable by documenting the following for
>  each and every cable run:
>
>    1) Signal-to-noise ration >10 dB for Ethernet & Token Ring
>    2) Near-end crosstalk (NEXT) >23 dB for Ethernet, >30.25 TRing
>    3) Total distance (must be >329 feet)
>    4) Attenuation <11.5 dB for Ethernet and <14.5 TRing
I think that 3) should have been "<329 feet"

Finally, will a cheapish TDR testing unit be much help in predicting cable
quality at CDDI speeds? I would guess that most units employ a tunnel-diode
to generate a sufficiently sharp edge, but what about the rest of the
electronics. Perhaps the line S/N figure would still be useful but maybe
crosstalk less so.

PS for ATM's 200Mbps raw rate, is it likely that all four UTP pairs will be
used?

an email copy of any netnews reply would be muchly appreciated - will
summarize if sufficient interest.

cheers,
X500: @c=AU [I'm about to update VTHRC entries, soon...]
       @o=University of Queensland
        @ou=Physiology and Pharmacology Department
         @ou=Vision Touch and Hearing
          @cn=Danny Thomas
           @rfc822Mailbox=vthrc@cc.uq.oz.au

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Date: 07 Oct 92 18:23:45 EST
From: IMAGING.CLUB@OFFICE.WANG.COM ("Imaging Club")
Subject:  Wang OPEN/image, Interoperability & Network Integration at Networld

Wang will be showing its OPEN/image document-imaging product line,
along with its network integration products and services at the
NETWORLD 92 show in Dallas October 13, 14 and 15.  Hours are from
10:00 am to 5:00 pm, except for 10:00 to 4:00 on the last day.

There will be speakers at the Wang booth discussing document imaging on
NetWare LANs, along with interoperability of different protocol stacks.
There will be time for questions and answers after these 15 to 20 minute
seminars.  The Wang booth is number 3637 and is located on the second level,
almost in the very center.  It will have ample seating for the large
audiences expected.

Michael.Willett@OFFICE.Wang.com

-------------------------------------------------------

Date: 08 Oct 92 10:54:47 EST
From: IMAGING.CLUB@OFFICE.WANG.COM ("Imaging Club")
Subject:      NetWare/VINES Integration

The September 28 issue of LAN TIMES has a rather interesting
article entitled "NetWare/VINES Integration Via One LAN
Adapter Card."  This article describes how the integration
was performed at the Student Loan Marketing Association in
Washington, using software tools from a software development
firm.  (This article has nothing to do with Wang LAN products
or integration services.)  If anyone would like a xerox copy
of the article, please send me your address and I will be
happy to air mail you a copy (including our VINES friends in
the Netherlands).  (There's a big, useful graphical diagram of the
total installation, plus a listing of the Protocol.ini file, so that
is why it makes sense to send out xerox copies, rather than Email a
rekeyed copy.)

Michael.Willett@OFFICE.Wang.com

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End of BIG-LAN Digest
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