agollum@engr.uky.edu (Kenneth Herron) (07/25/89)
Hello, our company is moving into new offices, and we're having the thin ethernet prewired along with the phone lines. Now, the guy doing the wiring has never done an ethernet setup before, though he is a wiz with telephones and does know something about coax in general. We purchased all the network stuff through a firm in California (it's a long story) so there is really no local dealer we can turn to for help. My question is quite simple: all the docs we have on installing the cables show both halves of the cable running right up to the back of the computer, and the T connector attaching directly to the network card in the PC. Does it HAVE to be this way? Can we keep the main cable and the T in the wall and run a short piece of cable to the network card? How long can this stub piece be? Assuming we can't do this, any suggestions for doing this wiring aesthetically? Many thanks in advance, Kenneth Herron
kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (07/26/89)
In article <2946@ukecc.engr.uky.edu> agollum@ukecc.UUCP (Kenneth Herron) writes: > >My question is quite simple: all the docs we have on installing the >cables show both halves of the cable running right up to the back of the >computer, and the T connector attaching directly to the network card >in the PC. Does it HAVE to be this way? Can we keep the main cable >and the T in the wall and run a short piece of cable to the network card? >How long can this stub piece be? Assuming we can't do this, >any suggestions for doing this wiring aesthetically? > Thin Ethernet is almost a literal replacement for the thick cable. Since transceivers are installed *on* thick cable, it follows that thin-net transceivers are installed *on* the thin cable. Since the transceiver is usually onboard the interface card, the cable has to come all the way. Now if you want to use thin exactly like thick, get outboard transceivers and you can run regular xcvr cable to the wall or up in the ceiling. DEC is the arch-conservative authority on all things Ethernet. Their DECconnect plan uses thin net only in star configured wiring. There is only one cable to each outlet. You run a patch cord from the single wall outlet to the back of the node, put a T on the node, plug the patch cord in one side and a terminator on the other side of the T. This means one DEMPR port per active outlet. This negates the moniker "cheapernet". So people daisychain, trying to save bucks. For those who simply *must* daisychain thin-net and get "cheapernet", I recommend the AMP Thin TAP solution. They have a special wallplate with shorting bar and a dual coax patch cable with integral T. This allows you to daisychain aesthetically thru the walls with nice looking faceplates. You can also plug and unplug without taking down the rest of the leg. The hardware looks robust, but we have not yet given this stuff a good trial. Beware. MY PERSONAL WARNING: Don't take the daisychaining too far or you, as net manager and troubleshooter, will live to regret it. No matter how good the AMP stuff might be, you will come to grief if you have to debug 15 connections on each leg. Stretch your DEMPR ports to maybe four outlets or so. That should be enough upfront savings. Remember, you can daisychain to your heart's content inside a lab or terminal room and not suffer diagnostic nightmares. Remember, too, that you can run extra wire and not use it. It's relatively cheap. But not too much daisychaining- it is just too difficult to debug media problems. Since we have not yet had time to evaluate the AMP stuff, consider my recommendation as preliminary. There may be other sources for the same thing, look around. --Kent England, Boston U
rh1m+@andrew.cmu.edu (Rudi Jay Halbright) (07/26/89)
I just went through this recently myself. Unfortunately running a wire from the T connector to the ethernet card put to much of a load on the card and risks burning it out (I was told this by a technician at Western Digital) As far as keeping things neat goes you have several options, basically the neater you want it to be, the greater expense you will inccur. The ideal would be to wire inside of the ceilings and walls. This is difficult and expensive. You could simply wire down the walls and through the ceiling if you have a dropped ceiling with reasonable ease. You can get plastic covers for the wires at most larger hardware stores. These plastic covers can be painted to match the walls. -Rudi Halbright rh1m@andrew.cmu.edu
craig@hprnd.HP.COM (Craig Blackwood) (07/26/89)
> agollum@engr.uky.edu (Kenneth Herron) / 6:54 pm Jul 24, 1989 / > > My question is quite simple: all the docs we have on installing the > cables show both halves of the cable running right up to the back of the > computer, and the T connector attaching directly to the network card > in the PC. Does it HAVE to be this way? Whether or not it has to be this way depends on the network interface card on the machines that you are connecting. You might be able to plug an AUI cable into the card and plug the MAU into the T connector on the floor or near the wall. > Can we keep the main cable > and the T in the wall and run a short piece of cable to the network card? NO. > How long can this stub piece be? Assuming we can't do this, > any suggestions for doing this wiring aesthetically? Did you consider Starlan 10 (i.e. 10BaseT) instead of ThinLAN? The guy that is a wiz with telephone wiring would also be a wiz with this. To use StarLAN 10 either 1) your network interface cards would have to have a StarLAN 10 connector or 2) you could use a StarLAN 10 MAU. HP makes a number of StarLAN 10 products (I wonder why I thought of them first :-), I believe that ATT, UB and SynOptics also have StarLAN 10 products. > > Many thanks in advance, > Kenneth Herron > ---------- Hope the information helps. Craig Blackwood Hewlett Packard Roseville Networks Division craig@hprnd.rose.hp.com OR craig%hprnd@hplabs.hp.com
davew@gvgpsa.GVG.TEK.COM (David C. White) (07/26/89)
In article <2946@ukecc.engr.uky.edu> agollum@ukecc.UUCP (Kenneth Herron) writes: >My question is quite simple: all the docs we have on installing the >cables show both halves of the cable running right up to the back of the >computer, and the T connector attaching directly to the network card >in the PC. Does it HAVE to be this way? Can we keep the main cable >and the T in the wall and run a short piece of cable to the network card? >How long can this stub piece be? Assuming we can't do this, >any suggestions for doing this wiring aesthetically? You will be breaking the standards if the tee doesn't connect directly to the station. I forget the exact specification, I'm sure somebody will correct me, but I think it is about 2.7 cm from the tee. Some people have mentioned in the past that they have gotten away with having a stub cable coming from the tee to the station, but this breaks the spec and eventually your network will break and then you are going to have a massive rewiring problem on your hands. I have seen something about some sort of cable that looks like one cable and makes the proper connection to the station, but is in actuality two cables inside. Somebody may be able to point you to this product. My recommendation is to go with twisted pair and forget the thinwire. With twisted pair you can run voice and data to each office with only one drop, and it certainly simplifies things for adding new connections or making moves. -- Dave White Grass Valley Group, Inc. VOICE: +1 916.478.3052 P.O. Box 1114 Grass Valley, CA 95945 FAX: +1 916.478.3778 Internet: davew@gvgpsa.gvg.tek.com UUCP: ...!tektronix!gvgpsa!davew
lance@belltec.UUCP (Lance Norskog) (07/27/89)
In article <2946@ukecc.engr.uky.edu>, agollum@engr.uky.edu (Kenneth Herron) writes: > Hello, > > our company is moving into new offices, and we're having the thin > ethernet prewired along with the phone lines. > > ... > > My question is quite simple: all the docs we have on installing the > cables show both halves of the cable running right up to the back of the > computer, and the T connector attaching directly to the network card > in the PC. Does it HAVE to be this way? Can we keep the main cable > and the T in the wall and run a short piece of cable to the network card? > How long can this stub piece be? Assuming we can't do this, > any suggestions for doing this wiring aesthetically? > > Many thanks in advance, > Kenneth Herron I have two comments to make about your questions: 1) No, you can't run a stub from the tee to the computer. I'd tell you why, but I flunked analog electronics. Ethernet pushes electrical cable to the outer limits of its usefulness. 2) You have picked a bad time to ask advice from the net. If you run thin Ethernet, aka rg-58, through the wall, you'll be sorry. Morning, noon and night. You'll go to the Justice of the Peace and change your name to Job. Thin Ethernet is unreliable (in particular the connectors) and was designed as a cheap alternative to Ethernet. It is only suitable for connecting one or more computers in the same room. Ethernet through the wall should today be thick Ethernet (big yellow cable) or tranceiver cables. You should put a 4-, 8-, or 16-port multiport transceiver in each room which has more than one computer. Ethernet through the wall tomorrow should probably be done with the Ethernet-over-Twisty-Pair standard that is working it's way out of the womb. (Ignore all recommendations about Twisty Ethernet until it's a standard, and standard equipment has been shipping for at least 6 months so that the industry can discover the gotchas by living with them.) Lance Norskog Sales Engineer Streamlined Networks
kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (07/28/89)
In article <383@belltec.UUCP> lance@belltec.UUCP (Lance Norskog) writes: > >Ethernet through the wall tomorrow should probably be done with the >Ethernet-over-Twisty-Pair standard that is working it's way out of the womb. >(Ignore all recommendations about Twisty Ethernet until it's a standard, >and standard equipment has been shipping for at least 6 months so that the >industry can discover the gotchas by living with them.) > We've been using the Cabletron UTP gear for about that long. It is so close to what 10BaseT will be (whatever it turns out to be) that there is no question that it now works like 10BaseT will, except that conformance must be more exact to guarantee interoperability. You may wish to wait for 10BaseT compliant hardware, but rest assured that it will work when you buy it, at least if you buy Cabletron. (I have no relation to Cabletron and I have no direct experience with the other vendor products which will also work well over UTP, 10BaseT or not.) --Kent England, Boston University
rh1m+@andrew.cmu.edu (Rudi Jay Halbright) (07/28/89)
The three conductor wire mentioned (2 conductors plus shield) is called triax and is roughly twice the price of coax. Several companies include Belden make it, I can look up the Belden number if anyone is interested. -Rudi Halbright rh1m@andrew.cmu.edu
hjp@bambam.bedrock.com (Howard J. Postley) (07/28/89)
In article <2946@ukecc.engr.uky.edu>, agollum@engr.uky.edu (Kenneth Herron) writes: > My question is quite simple: all the docs we have on installing the > cables show both halves of the cable running right up to the back of the > computer, and the T connector attaching directly to the network card > in the PC. Does it HAVE to be this way? Can we keep the main cable > and the T in the wall and run a short piece of cable to the network card? > How long can this stub piece be? Assuming we can't do this, > any suggestions for doing this wiring aesthetically? Guess what? This is type type of situation that was envisioned when ethernet was designed at Xerox! The original idea was to run thick cable around, put xceivers in wall plates and plug the computer into the wall plate with a drop cable. Since the drop cable can be up to 50 meters, this also gets around a lot of length problems. If your distances are short enough to run thin cable, you can do about the same thing. Get xceivers with BNC connectors on them (cheap ones are available for < $40) and put them in wall plates. This eliminates looping the thin cable, shortens distances and looks better. It's a little more expensive than just running the cable to the card and wastes the xceiver that is built in to it but so what, IT LOOKS GOOD! You can save money with fan-out boxes on thin net just the same as with thick net but that is installation specific. //hjp -- Howard Postley internet: hjp@bambam.bedrock.com Ideal Point, Inc. uucpnet: uunet!bambam!hjp phonenet: +1 213 578 6901 uspsnet: 13428 Maxella Av M/S 236; Marina del Rey, CA 90292
DAVEH@WL14.Prime.COM (07/29/89)
You can also get some cable called 'siamese' cable, which is (obviously?) two coaxes in a 'figure 8' configuration. Cabletron call it 'Siamese Thin Wire', part# 706014. You can also get an interesting looking connector from AMP called the 'Thinnet Tap' system (#222503-1). This is a connnector that plugs into a wall plate, breaking the through connection and comes complete with a cable and connector. I don't know how reliable the connection is tho'. Dave Hill Disclaimer: I don't work for Cabletron or AMP, I work for:- ------------------------------------------------------------------------------- Dave Hill, Prime Computer R&D, Willen Lake, Milton Keynes, MK15 0DB, UK. Internet: DAVEH@WL14.Prime.COM "My eyes aren't what they used to be... UUCP: ...primerd!wl14!daveh ...no, they used to be my ears" Dog and Bone: +44-908-666622 x461 -------------------------------------------------------------------------------
tsmith@usna.MIL (Tim G. Smith ) (07/29/89)
> 2) You have picked a bad time to ask advice from the net. > If you run thin Ethernet, aka rg-58, through the wall, you'll be > sorry. Morning, noon and night. You'll go to the Justice > of the Peace and change your name to Job. Thin Ethernet is > unreliable (in particular the connectors) and was designed > as a cheap alternative to Ethernet. It is only suitable for > connecting one or more computers in the same room. > >Ethernet through the wall should today be thick Ethernet (big yellow cable) >or tranceiver cables. You should put a 4-, 8-, or 16-port multiport >transceiver in each room which has more than one computer. > >Ethernet through the wall tomorrow should probably be done with the >Ethernet-over-Twisty-Pair standard that is working it's way out of the womb. >(Ignore all recommendations about Twisty Ethernet until it's a standard, >and standard equipment has been shipping for at least 6 months so that the >industry can discover the gotchas by living with them.) > >Lance Norskog >Sales Engineer >Streamlined Networks Ummm exscuse me, but can you please explain your reasons for making statements likes the above. Please provide case studies to back up your complaints against thin ethernet. I have the exact opposite feelings. Thick ethernet is a royal pain and can be a major nightmare to deal with. At my former job I personally removed almost all of the thick ethernet cable and replaced it with thin. The network in question consisted of at least 5 subnets and a whole lot of cable. A poorly desinged thin net can be hellish but not much worse then the average thick net. I designed my thin net as a star. A single RG58 was run to each office/lab with all of the wires for each floor starting in a central closet where there was a rack with Multi Port Repeaters (Cabletron MR900Cs and Cabletron MMACs). From each floor at lest one (and ususally more) RG58 was run down to the main computer room where the network head was located (the backbone linking all of the various thin/thick/FO subnets was completely located in one rack). The cost of the additional cable is trivial- the cost of the MPRs and/or MMACs is not too outrageous for the convenience, flexibility, reliability, and sanity they provide. Some of the advantages of star wiring are: 1) Reconfiguring the network is trivial. If office X changes hands from being in the MechE dept to EE then it takes all of two minutes to move the office from the MechE subnet to the EE subnet. Try doing that with any sort of daisy chained wiring plan- not easy. 2) MPRs (or MMACs or any other fully compliant IEEE 802.3 repeater) will isolate any faulted segment from the rest of the network. So if someone decides to take the net apart in his office the only folks affected are the guilty party and the guilty party's office mate. 3) Locating problems with a star network is much easier than with a daisy chain scheme. You simply go look at the MPRs and see if there are any fault lights on. If so you know that the problem is between the office and the MPR so you just fire up the TDR and see what is going on (this assumes that when the wiring was installed it was TDRed from both ends and the measurments recorded). If the problem is not between the office and the MPR than it must be in one of the other segments leading back to the network head (provided there is one)- if the network has been designed well there should be cleary defined segments that can be debugged one by one until the problem is found. Some other reasons I like thin net: - no vampire taps! - connectorizing is trivial- anyone can do it with a bit of practice - the wire is smaller and easier to work with - many hosts have both BNC and DIX plugs on them- if you use the BNC you do not need an external XCVR - neat repeaters like the Cabletron MMAC exist that can collect very useful network loading statistics on each cable segment and can also support redundant links between the MMACs which means that your most critical segments can be well protected from failure. With all of that said the most important thing is to design the network carefully. A well designed network can use any media and be reliable- I just happen to prefer thin net as my media. Twisted pair also is pretty neat, I just don't have much experience with it. Star wiring and network heads with "backbones in a rack" are real winners when it is debug time even if they cost more to implement. Having the right tools to debug is also essential. I would not build any network without having a TDR for each type of media I use (ok- I have to admit I did use fiber without haing a FO TDR but I did have some other stuff including a LED attached to a 9 volt battery for shining down the fiber and I did eventually get a signal meter from Siecor for about $800). There is nothing wrong with thin net- just with poorly designed thin nets. later, Tim Smith (formerly of the US Naval Academy, and still getting news at usna.) US mail:US Army, BRL E-mail: SLCBR-SE internet:tsmith@brl.mil Aberdeen Proving Grounds, MD 21005-5066 uucp :...!uunet!brl!tsmith MaBell :(301)278-6678 (or 6808) Autovon: 298-6678 Disclaimer: The DoD does not pay me enough to speak for them.
tawab@net4.UUCP (07/29/89)
/* ---------- "Simple thin ethernet question" ---------- */ Hi, Kenneth Herron >Hello, >our company is moving into new offices, and we're having the thin >ethernet prewired along with the phone lines. Now, the guy doing the >..... >My question is quite simple: all the docs we have on installing the >cables show both halves of the cable running right up to the back of the >computer, and the T connector attaching directly to the network card >in the PC. Does it HAVE to be this way? Can we keep the main cable >and the T in the wall and run a short piece of cable to the network card? >How long can this stub piece be? Assuming we can't do this, >any suggestions for doing this wiring aesthetically? >Many thanks in advance, First I tried to mail but it bounced, where are you, in UK, US, ??? We have a Yellow Cable Ethernet, but I guess there are just some differences in the lenght of the Cable. I can't belive the you are conecting the "T" (I guess "T" == Tranciever ?) to the Network-Card. We have superminis and pc's but all are connectet via a Tranciever-Cable to the network-card. The way I connect Machines to Ethernet is like the following pictures: <- 2.5 m -> ===T===========T=========================== Ethernet(Max 500 m) | | |-Tranciever Cable(Max 20 m) | | [pc] [UNIX] An other posibility: ===============T========================== Ethernet(Max 500 m) |-Tranciever-Cable | [Fanout whith 7 posible connections] 0 0 0 0 0 0 0 | | |-Tranciever|Cable | | [pc] [An Second Fanout] and so on (I think up to 5 Fanouts) I hope I could help you with these pic, if you have any more questions Robin Tawab NIXDORF COMPUTER AG Dep DTSW 2-4 Berliner Str. 95 D-8000 Munic (West Germany) Tel.: xxx-89/3601-3171 eunet: tawab.muc@nixpbe.UUCP !USA: mcvax!unido!nixpbe!tawab.muc USA: uunet!linus!nixbur!tawab.muc
lance@belltec.UUCP (Lance Norskog) (08/01/89)
Mr. Smith is absolutely right about star-shaped networks. Star-shaped networks are the easiest to maintain in the long run because all failures can be chased down via a binary search method, usually at one location. That is, you stand if fron of the rack, and play with plugs until you have found the bad cable, instead of running around with a clipboard building a large test log and trying to make sense of it. This is why IBM's Token Ring, from the beginning, was wired physically as a star rather than daisy-chaining cables directly between computers. (Possibly the only wise architectural decision in TR :-) However, my point was that the BNC connectors on Thin Ethernet tend to degrade when you flex the cables. If you run them through walls you should leave a long tail at each end so that you can keep chopping off bad connectors and re-connectorizing them. Thick Ethernet is better in this regard, and also gives cleaner signal. So, you should follow Mr. Smith's architectural plan but use Thick yellow cable instead of Thin black stuff. Besides, with the yellow stuff nobody gets the bright idea of using 75ohm video cables instead! Lance Norskog Sales Engineer Streamlined Networks
fmr@cwi.nl (Frank Rahmani) (08/01/89)
> Nf-From: net4.UUCP!tawab Jul 28 09:38:00 1989 > /* ---------- "Simple thin ethernet question" ---------- */ > Hi, Kenneth Herron > >Hello, > >My question is quite simple: all the docs we have on installing the > >cables show both halves of the cable running right up to the back of the > >computer, and the T connector attaching directly to the network card > >in the PC. Does it HAVE to be this way? Can we keep the main cable > >and the T in the wall and run a short piece of cable to the network card? > >How long can this stub piece be? Assuming we can't do this, > >any suggestions for doing this wiring aesthetically? > First I tried to mail but it bounced, where are you, in UK, US, ??? > We have a Yellow Cable Ethernet, but I guess there are just some differences > in the lenght of the Cable. I can't belive the you are conecting the "T" > (I guess "T" == Tranciever ?) ...dumped nice network pictures... Sorry, wrong guess.The 'yellow cable' is definitely 'thick ethernet' and as such your description are correct, but only for that kind of network. The question however was about 'thinwire ethernet', which is a 50 Ohms coax cable about 6mm dia. The physical architecture is a little bit different from thickwire installations. Thickwire: --------- --------- |transc.| |transc.| _______________| |________| |____________final resistor yellow cable | | y.c. | | y.c. --------- --------- blue dropcable-> | b.d.-> | |__ |__ to your workstations ethernet port Thinwire: ---------------| |---------------| ||<--final resistor | | | || | | | | --- --- this is the T- | connector (also | called BNC-T-connector in question ------- -------- | | | | your workstations The T connector is just a three way connector with 2 male and 1 female (or the other way around) outlets, just mechanical, no electronics involved. According to the specs ,there is NO cable allowed between this T-piece and the workstation(s). I have seen people reporting in this group having used cables up to seven meters long without any problems. If you have a big network ,especially many thinwire segments connected by bridges and/or multiport boxes to thickwire backbone(s) this is a definite NO GO! You will have lots of unexplainable errors. For the esthetic part, this is what we do: 1)use twin cables (just two thinwire cables glued together, don't mix up with the IBM twinwire network cables, which are coax cables with two inner condu- ctors).So only one cable leads up to your workstation. 2)use right-corner connectors between your cables and the T-piece. This will prevent you from getting two great bows in your cable. | | this |-----| instead of /-------------\ \ / / \ \ / | | \ / | | || \ / Sorry this has gotten kind of long, but difficult to explain otherwise. Regards fmr@cwi.nl -- It is better never to have been born. But who among us has such luck? Maintainer's Motto: If we can't fix it, it ain't broke. These opinions are solely mine and in no way reflect those of my employer.