Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uwm.edu!uwvax!umn-d-ub!umn-cs!wsmith
From: wsmith@umn-cs.CS.UMN.EDU (Warren Smith [Randy])
Newsgroups: comp.dcom.lans
Subject: Re: Why Ethernet-over-twisted-pair, anyway?
Keywords: Ethernet, twisted pair, cost-benefit
Message-ID: <17360@umn-cs.CS.UMN.EDU>
Date: 28 Nov 89 01:50:18 GMT
References: <4645@blake.acs.washington.edu>
Reply-To: wsmith@umn-cs.cs.umn.edu (Warren Smith [Randy])
Organization: CSci Dept., University of Minnesota, Mpls.
Lines: 47

In article <4645@blake.acs.washington.edu> djo7613@blake.acs.washington.edu (Dick O'Connor) writes:
>OK, Ethernet-over-twisted-pair fans, why is this innovation something to
>get excited over?  From theoretical or practical standpoints, why is 
>this new standard a boon to PC networking?
>
>I've heard comments about one of the obvious benefits: the cost of twisted
>pair wiring, as opposed to the (higher) cost of RG-58 thin coaxial cable.
>Perhaps cabling is easier, too.  But is it really cheaper than standard
>thinnet cable for small groups?

... example omitted

>I guess what I'm after is the answer to: Is twisted pair Ethernet a  
>special-purpose solution for large LANs (where wiring costs might predom-
>inate) or small spurs off a large LAN?  Where's the benefit for a small
>standalone workgroup?

Here are what I see as the advantages of twisted pair Ethernet:
  1) Low cost for cable
     minimal benefit - labor is usually the major expense in a large
     installation, equipment is in a smaller one
  2) Ability to use existing cable plant in some cases
  3) Common wiring type (most of your installer types feel comfortable with it)
  4) Small cable - fits in conduit easier (not much different from thinnet tho)
  5) Don't have to worry about termination
  6) Same wiring can have multiple uses (eg. telephone, Appletalk, RS-232)
     some won't view this as a feature when people plug things in wrong...

And numerous other quibbles about how easy/nice/reliable/stupid/junky/etc
the connectors are.

The IEEE 802.3T standard is not low cost!  This will hopefully change as
802.3T devices are mass produced, and vendors start competing.  I have
some doubts that it will ever be a super cheap option (comments?).  Other
non-standard twisted pair products can be alot cheaper.

I really don't think there is any significant advantage to using a twisted
pair product for the small workgroup as you described (7 stations in close
proximity).  I wouldn't relate the benefit of twisted pair to the
size of the LAN, but rather the wiring requirements.

Randy
-----
-- 
Randy Smith
wsmith@umn-cs.cs.umn.edu
...!rutgers!umn-cs!wsmith