jsa00564@uxa.cso.uiuc.edu (11/29/89)
/* Written 2:47 pm Nov 27, 1989 by djo7613@blake.acs.washington.edu in uxa.cso.uiuc.edu:comp.dcom.lans */ /* ---------- "Why Ethernet-over-twisted-pair, any" ---------- */ 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? [stuff deleted] 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? "Moby" Dick O'Connor ** DISCLAIMER: It would Washington Department of Fisheries ** surprise me if the Olympia, Washington 98504 ** rest of the Department Internet Mail: djo7613@blake.u.washington.edu ** agreed with any of this! /* End of text from uxa.cso.uiuc.edu:comp.dcom.lans */ The cost of cabling is not the issue. Yes, twisted pair cable is cheaper by the foot than thinnet or other types... However, this savings is not worth worrying about. Your cost savings will be in installation, and substantial savings for moves and/or adds. With the star-based systems, adding a node only requires running one additional cable (at the most, all of our office phone jacks were prewired with extra pairs for data, and we have dual jacks everywhere, so we never run additional cable to add a new node). As in our situation, I can typically add a user's PC to the network (not including NIC installation) in about 30 minutes. This is not a "best" time, but an average. In my installation, we have underwent several remodelings, and have been using twisted pair for about 1.5 years. With all the moves that occur, i if I had to re-route a thin ethernet bus every time (well, not every..) I wanted to move an office, the net would be down more than it was up..... As for the benefits for small installations. You price for a concentrator was quite high.. I buy SynOptics Lattisnet equipment, and a standalone 8 connection workgroup concentrator will run a retail $1495. While the NIC's are more expensive than standard Ethernet, they are still much cheaper than token ring. ---------------------------------------------------------------------------- Jeff Autor "I need a disk de-frag utility j-autor@uiuc.edu for my brain...." Student at the University of Illinois Also Affiliated with Valmont Electric, Danville, IL Opinions (and facts) expressed are my own. ----------------------------------------------------------------------------
german@uxh.cso.uiuc.edu (11/29/89)
Well here is my $0.02 on the issue of using UTP for ethernet.
Cost/flexibility/managment.
If I were to design and pull networks just to hit a few office with very
little change anticipated then I might consider a thin coax daisy chained
option, but I would tend to avoid this as a general solution.
If I were to use thin coax I would pull home runs to a central location,
repeat every segment from a concentrator that per port network managment.
I would tend to use something SNMP based. This is an expensive solution,
but one that in a large environment would isolate faults, provide centralized
managment of the physical plant.
I currently lean towards using UTP distribution. I will feel alot more
comfortable once 10baseT is approved as I really would like to have the
flexibility to choose my comonents from multiple vendors. In our environment
we have 4 pairs of UTP at every location with a telephone that is reserved
for data. Thus I can avoid additional labor and material costs for the
distribution into the offices. I run every connection back to a repeated/
managed port in a central location. The connection in the office can be
as unobtrusive as an 8 wire jumper cable from the jack location to a jack
on a 10baseT card. With quantity (100) discounts we can approach a solution
that would allow us to connect a PC (ISA bus) to a building ethernet for
less than $400 per machine for the ethernet card/jumper cable/multiport
repeater w/ network managment. This assumes we can fully utilize the 8 or
12 port 10baseT cards in a central concentrator.
This is not a general solution and is very dependent on the site. Distances
are often the limiting factor when choosing UTP and large buildings will
require that you have more than one location for the concentrators.
4 floors is about the limit you can stretch to from a central location
depending on the distance to the far corner riser. In some cases we will
end up with a hybrid network.
What is important to me may not be the deciding factors for your design and
it is always important to get a feel for what the users want before you
dump some design on them. In large departmental networks (>100 nodes)
we very strongly recommend some sort of network managment to be built in.
As the users become more dependent on the network to get their work done
the more important reliability becomes.
Greg German (german@sonne.CSO.UIUC.EDU) (217-333-8293)
US Mail: Univ of Illinois, CSO, 1304 W Springfield Ave, Urbana, IL 61801
Office: 129 Digital Computer Lab., Network Design Office