Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!dino!ux1.cso.uiuc.edu!ph-meter.beckman.uiuc.edu!melanie From: melanie@ph-meter.beckman.uiuc.edu (Melanie Anderson) Newsgroups: comp.protocols.tcp-ip Subject: Re: Thinwire vs. Thickwire Message-ID: <1989Oct4.174149.9451@ux1.cso.uiuc.edu> Date: 4 Oct 89 17:41:49 GMT References: <68@lcc.la.Locus.COM> <8909291306.AA06775@jvnca.csc.org> Sender: news@ux1.cso.uiuc.edu (News) Organization: University of Illinois at Urbana Lines: 136 In article <68@lcc.la.Locus.COM>, eric@lcc.la.Locus.COM (Eric Peterson) writes: > > In article <8909291306.AA06775@jvnca.csc.org> aggarwal@JVNCA.CSC.ORG (Vikas Aggarwal none) writes: enough thinwire bashing, already. im coming into this debate late; but let me throw in my 2pence anyhow: some background: the beckman institute is a research lab/think tank at the uofi. we have over 300,000 sqare feet on five floors plus a basement. the building is designed to house over 700 researchers in all types of research settings from offices to computer labs to chemistry and mri. the building is not yet at capacity and we already have over 300 computers on site ranging from zenith laptops to vaxes, ardents and apollos to a 32K processor connection machine. the design goal of the network was to provide high connectivity to every office, lab, conference room and public area. therefore every room in the building (excluding bathrooms and kitchens!) has at least one connection to the building network. this presented some interesting cable design problems, resulting in (if you dont belive me do the math) the discovery that it would be 1. enormously expensive 2. very difficult 3. would not meet connectivity requirements to use thick ethernet. the entire building is wired with thinwire ethernet, close to 16 miles of it, in fact. the cabling design is a rib-and-spine approach. areas of the building were carved into logical ethernets (ribs) and each rib connects, via cabletron thin repeaters, to a 100Mbit beckbone (good pun, huh?) built out of network systems en641 routers. it WORKS, it works GREAT. i have had zero problems with the wiring, ~zero problems with the repeaters (out of over 700 repeater ports i have had 1 fail). somebody comes in, they get a chunk of cable from central stores for 6 bucks, they come to me, i give them a new IP number and tell them what their default gateway ip address is (for those brain-dead ips out there!), they go up to their office, they plug in, and off they go! in fact, this wiring scheme and these repeaters have worked so well the same system is being used in a 400-port new installation in the psychology building on campus, in the cedar project addition (100+ ports) and will probably be used in other new construction. > > > >Just to collect one's views on Thinwire ethernet vs Thickwire ethernet, > >I am listing what I know about the topic: > > > >THINWIRE > > > > Flexible, Low cost ( app. $3.00 per meter ), 10 Mb bandwidth, > > Max segment length - 185 meters (30 nodes per segment), One > > multiport repeater can handle upto 8 segments where are you buying your repeaters from? here at beckman i have 33 thinwire repeaters purchased from cabletron. they support anywhere from 12 thin and two thick connections to 84 thin segments and two thick. also, if you are using a repeater, you only get 28 nodes a segment. the plus to using thin repeaters over conventional thick is that most reapeaters are smart enough to shut down a port if it detects a bizzare electrical condition like a short, open or fluctuation in resistance. in exremely large networks, this intelligence can save hours or days of time. it also fixes the problem below. > > From past experience, I recommend this for only very small or > temporary nets. The cable is fragile, and the cable -> BNC > connection is especially susceptible to breakage (we once had > a janitor vacuuming the floor accidentally hit the cable and > yank it out of the BNC connector, he noticed the damage and > managed to push the cable back into the connector - needless > to say, it was a poor connection and that whole floor of the > building suffered from intermittent Ethernet problems for > several days while we looked for the problem). > first, i would bet that a thick transciever cable would be damaged by this kind of rough treatment, as well. also, you might want to suggest that if someone breaks something, they report it, rather than try to fix it... second, i would suggest you investigate who is doing your bnc terminations. i have over 2000 terminations in this building and very few (~25) have been demolished, usually by furniture being set on them. i would argue that you would have the same problem with el-cheapo thick connections. i do have wall and floor boxes installed. NO wiring should lie on a floor, be it rs-232, power, ether or piano. > >THICKWIRE > > > > More resilient for running through floors and ceilings, Higher > > cost (app $11.00 per meter), 10 Mb bandwidth, Max segment > > length - 500 meters > > > >Based on the above, I would choose thickwire ONLY if the length of the > >segment had to be more than 500 mts or if the wire was going to run > >through adverse areas. > thin ethernet with a toughened-up pvc or teflon coating is available for adverse-condition or plenum applications. like i said, even our long underfloor and overhead runs are thinwire. thick is appropriate for certain applications. i strongly believe, however, that whatever your wiring application, that ribs-n-spine be used in any new large network. saves you much time and effort and grief. it is flexible, reconfigurable, and expandable. try to divvy your network up into ribs and then firewall them off from each other so that one looney machine wont crash everyone. whatever you do, PLAN for cut wires, smushed connectors, gonzo transcievers, crazy ethernet cards, and broken software. DONT assume all computers will play well with others. expect the worst because it WILL happen. > > Another solution is to use multiport transceivers to disribute > the Ethernet. It is much less susceptible to damage (or I should > say, if damage _does_ occur, it doesn't propagate throughout the > network.) I believe the spec allows xcvr cable runs up to 50 > meters away, and the multiports that I've seen allow up to two > levels of stacking the xcvrs. Another advantage is that some > Ethernet boards do not have the built-in thin wire BNC connector. > yeah, you have to buy a transciever for any machine that doesn have an on-board transciever. the thin transcievers are the same price, or cheaper, than thick. you can also put a delni-alike on thinwire ethernet (see above.) Melanie Anderson melanie@ph-meter.beckman.uiuc.edu Beckman Institute 217/244-1079 Unversity of Illinois ----------------------------------------------------------------------------- "N4634X, Champaign Tower, uhh, what's that hanging off your wing?" -----------------------------------------------------------------------------