rhp@INEL.GOV (Robert Powell) (12/13/89)
Our NeXTs arrived last Monday, so far our expectations have been exceeded.
However, the real test will come when we start developing software on them.
Our biggest problem right now is connecting our cubes to our ethernet. It
is a problem because our building is only wired with twisted-pair thick-net
ethernet. Our networking people tell me that I need a thick-net to thin-net
bridge or repeater, at a cost of around $2,600! Has anyone else out there
done this type of connection? If so, how did you do it and how much did you
pay? Please note: Our building is wired with TWISTED-PAIR thick-net, not
coaxial thick-net. I would much rather use $2,600 towards memory, Frame, and
other useful things. Any help would be greatly appreciated.
Bob
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izumi@violet.berkeley.edu (Izumi Ohzawa) (12/13/89)
In article <341@egg-idINEL.GOV> rhp@INEL.GOV (Robert Powell) writes: > >It is a problem because our building is only wired with twisted-pair thick-net >ethernet. Our networking people tell me that I need a thick-net to thin-net >bridge or repeater, at a cost of around $2,600! Has anyone else out there We, at UC Berkeley, have the same problem, and I am anxiously waiting our computer center people to come up with a solution. However, I noticed several articles back about a router/bridge made out of a cheap PC XT clone + 2 Western Digital Ethernet cards for under $800-900. If this box can have 1 twisted-pair Ethernet card and another thin-Ethernet card, it should do the job. Whoever posted that article, would you clarify this point? If you also know Model numbers of such Ethernet cards, please let us know. Thanks. Izumi Ohzawa, izumi@violet.berkeley.edu
lee@uhccux.uhcc.hawaii.edu (Greg Lee) (12/13/89)
From article <341@egg-idINEL.GOV>, by rhp@INEL.GOV (Robert Powell): " ... " Our biggest problem right now is connecting our cubes to our ethernet. It " is a problem because our building is only wired with twisted-pair thick-net " ethernet. Our networking people tell me that I need a thick-net to thin-net " bridge or repeater, at a cost of around $2,600! ... I thought thick-net and twisted-pair ethernet were different animals. There is a twisted-pair to thin-net converter in the DEC catalog for, I think I recall, $400 for a pack of 8. Something like that. I don't know whether that would be suitable. The subject of connecting thick-net to thin-net came up before in this newsgroup, and it was said that you can just stick them together directly with a connector. Following is some of that past discussion. Greg, lee@uhccux.uhcc.hawaii.edu >From: jbn@glacier.STANFORD.EDU (John B. Nagle) Newsgroups: comp.sys.next Subject: Re: My ramblings on the NeXT machine Message-ID: <17845@glacier.STANFORD.EDU> Date: 15 Nov 88 18:09:46 GMT References: <26812@ucbvax.BERKELEY.EDU> Reply-To: jbn@glacier.UUCP (John B. Nagle) In article <26812@ucbvax.BERKELEY.EDU> munson@renoir.Berkeley.EDU (Ethan V. Munson) writes: >3) Thin Ethernet -- NeXT has a Thin Ethernet connector. Here at Berkeley, > neither the EECS department or the academic computing service has > anything but thick ethernet. As of last week, even NeXT didn't > know where to find converters. Each converter will cost about > $200-300. Since these machines are targeted at professors, rather > than students, it may be hard to build short Thin Ethernets which > share one converter. Thick and thin Ethernet cable can simply be interconnected with coax adapters. Losses are higher in the thin sections, but the adapters themselves seem clean; I've looked at a mixed cable using a time-domain reflectometer, and I can see tranceivers and sharply bent cable, but not thick/thin adapters. Usually, you convert from thick to thin inside a wall, box, floor, or plenum, then bring two thin cables up to the machine, where they meet at a T connector attached to the back of the machine. Remember, the T connector must be directly on the back of the machine; any cable between the T and the computer causes reflections that trash data. If the entire cable is within the thin Ethernet length limit, everything should be safe. The appropriate adaptor is a constant-impedance UHF (female) to BNC (female) adapter. However, this is a hard-to-find adapter, and it may be necessary to combine a UHF (female) to BNC (male) adapter with a BNC-BNC barrel. Amphenol part 12025 is the adapter. John Nagle >From: jbn@glacier.STANFORD.EDU (John B. Nagle) Newsgroups: comp.sys.next Subject: Re: Followup to Who Has One? Message-ID: <17916@glacier.STANFORD.EDU> Date: 21 Dec 88 19:36:31 GMT References: <18496@agate.BERKELEY.EDU> Reply-To: jbn@glacier.UUCP (John B. Nagle) The simple, cheap solution to connecting thin to thick Ethernet is just to get the appropriate connector hardware. Thick Ethernet uses what are called "UHF" connectors, and thin Ethernet uses "BNC connectors." Adapters are available for under $10. See a Newark, Zack, or Arrow catalog for details. I've actually used such conversions, and couldn't see an impedance mismatch at the connector when examining the cabling with a TDR. Sharp bends (4" radius) in the thick Ethernet cable cause more reflections than a thick/thin transition. Remember how you hook it up. BNC T-connector on the back of the machine, two thin Ethernet cables to the place where you reach the big cable, two adapters to convert to thick Ethernet. Never put a section of thin Ethernet between the machine and the T-connector; the short arm of the T can't be more than a few inches before everything stops working due to reflections. John Nagle >From: kchen@Apple.COM (Kok Chen) Newsgroups: comp.sys.next Subject: Re: Followup to Who Has One? Message-ID: <22678@apple.Apple.COM> Date: 22 Dec 88 02:31:10 GMT References: <18496@agate.BERKELEY.EDU> <17916@glacier.STANFORD.EDU> Organization: Apple Computer Inc, Cupertino, CA In article <17916@glacier.STANFORD.EDU> jbn@glacier.UUCP (John B. Nagle) writes: > The simple, cheap solution to connecting thin to thick Ethernet is >just to get the appropriate connector hardware. Thick Ethernet uses what >are called "UHF" connectors, and thin Ethernet uses "BNC connectors." >Adapters are available for under $10. See a Newark, Zack, or Arrow >catalog for details. No, no. You want to use a "Type-N" connector, not a "UHF connector" for thick Ethernet. There IS such a thing called the "UHF connector," but that is NOT what you will find normally used on Ethernets. Those ancient enough may remember using the Tektronix 503 oscilloscope in undergrad labs (they were popular in the '60's). THOSE animals used UHF connectors. A "type-N" is VERY different, and definitely will not mate with a UHF type. Kok Chen {decwrl,sun}!apple!kchen Apple Computer, Inc. P.S. Someone (a Harvard prof., no less [but Physics, not EE :-) ] ) once claimed to me that BNC (the connector used in thin-Ethernets) stood for "Baby N-Connector." Said person is also author of the "The Art of Electronics" book you see in bookstores and once (40+ years ago :-) held the record for being the youngest amateur radio operator in W-land, so he may be right. (I doubt it, Paul :-) :-)) >From: gore@eecs.nwu.edu (Jacob Gore) Newsgroups: comp.sys.next Subject: Re: Followup to Who Has One? Message-ID: <12670010@eecs.nwu.edu> Date: 22 Dec 88 04:02:26 GMT Organization: Northwestern U, Evanston IL, USA / comp.sys.next / jbn@glacier.STANFORD.EDU (John B. Nagle) / Dec 21, 1988 / >BNC T-connector on the back of the >machine, two thin Ethernet cables to the place where you reach the big >cable, two adapters to convert to thick Ethernet. Just to make sure I understand you correctly: are you actually splicing a piece of thin Ethernet into a thick Ethernet? Jacob Gore Gore@EECS.NWU.Edu Northwestern Univ., EECS Dept. {oddjob,gargoyle,att}!nucsrl!gore >From: jbn@glacier.STANFORD.EDU (John B. Nagle) Newsgroups: comp.sys.next Subject: Re: thin/thick Ethernet Message-ID: <17925@glacier.STANFORD.EDU> Date: 22 Dec 88 18:08:22 GMT References: <18496@agate.BERKELEY.EDU> <12670010@eecs.nwu.edu> Reply-To: jbn@glacier.UUCP (John B. Nagle) Organization: Stanford University Lines: 26 In article <12670010@eecs.nwu.edu> gore@eecs.nwu.edu (Jacob Gore) writes: >Just to make sure I understand you correctly: are you actually splicing >a piece of thin Ethernet into a thick Ethernet? Yes. It works. Loss per unit length is higher in the thin cable, but unless you are pushing the length limits of the Ethernet cable, adding a few feet of thin cable isn't that important. You might think that the transition would produce reflections, but my experience is that it doesn't. Find a TDR and check for yourself. If you have a farm of NeXT machines or other small machines with thin Ethernet connectors, it might be better to tie them all together on thin cable and only have one thick/thin transition. But this is not mandatory. Always check the machines at the ends of the cable for high retransmit rates. This is the first symptom of excessive losses, and indicates that collisions are being undetected due to cumulative loss in the cable. This means the cable is too long, or too lossy; time to get out a TDR or put a repeater in the middle. If your thick/thin mixed cable falls within the length limitations for thin Ethernets, everything should work fine. Only beyond that length should it be necessary to worry much about the electrical properties of the cabling. John Nagle >From: gore@eecs.nwu.edu (Jacob Gore) Newsgroups: comp.sys.next Subject: Re: Re: thin/thick Ethernet Message-ID: <12670012@eecs.nwu.edu> Date: 22 Dec 88 21:29:25 GMT References: <17925@glacier.STANFORD.EDU> Organization: Northwestern U, Evanston IL, USA Lines: 23 / comp.sys.next / jbn@glacier.STANFORD.EDU (John B. Nagle) / Dec 22, 1988 / > In article <12670010@eecs.nwu.edu> gore@eecs.nwu.edu (Jacob Gore) writes: > >Just to make sure I understand you correctly: are you actually splicing > >a piece of thin Ethernet into a thick Ethernet? > > Yes. It works. Oh, I'm not surprised that it works. It just struck me as a rather inconvenient thing to do. When we have several thin-connector machines near each other, we do connect them all with thin-net, as you suggested. Except that our thick-cable networks are usually large-spread nets, with multi-user hosts on them as well as scattered workstations. We just don't like splicing into that net, even for inline transceivers. We use thick/thin repeaters for this kind of stuff. A repeater with one thick port and one thin port plus its transceiver and drop cable (for the think side) cost us about $1,000. If you are putting 5 or more stations on the thin side, the cost is quite reasonable. But for a single workstation, it's rather steep... Jacob Gore Gore@EECS.NWU.Edu Northwestern Univ., EECS Dept. {oddjob,gargoyle,att}!nucsrl!gore >From: jbn@glacier.STANFORD.EDU (John B. Nagle) Newsgroups: comp.sys.next Subject: Re: Re: thin/thick Ethernet Message-ID: <17934@glacier.STANFORD.EDU> Date: 23 Dec 88 17:01:57 GMT References: <17925@glacier.STANFORD.EDU> <12670012@eecs.nwu.edu> Reply-To: jbn@glacier.UUCP (John B. Nagle) Organization: Stanford University Lines: 12 I certaintly agree that a repeater to isolate important multi-user systems and servers from farms of little machines where the cables are accessable to many people is a valuable addition to a network. I was merely pointing out that thich/thin Ethernet transitions are not difficult to accomplish, should one wish to do so. Some people have found repeaters, as an active device and a single point of failure, to cause more trouble than they prevent. But that information is a few years old, and repeaters may be more reliable now. John Nagle
jacob@gore.com (Jacob Gore) (12/14/89)
/ comp.sys.next / izumi@violet.berkeley.edu (Izumi Ohzawa) / Dec 13, 1989 / > I noticed several articles back about a router/bridge > made out of a cheap PC XT clone + 2 Western Digital Ethernet cards > for under $800-900. If this box can have 1 twisted-pair Ethernet > card and another thin-Ethernet card, it should do the job. > > Whoever posted that article, would you clarify this point? I'm checking it out with the author of PCroute. You should be able to get a single-port thick-thin repeater for well under the $2,600 that Robert Powell quoted. Try Cabletron -- if I remember correctly, their educational price for one is about $800 (sorry, I have no clue about the non-educational price). Jacob -- Jacob Gore Jacob@Gore.Com boulder!gore!jacob
izumi@violet.berkeley.edu (Izumi Ohzawa) (12/14/89)
In article <5719@uhccux.uhcc.hawaii.edu> lee@uhccux.uhcc.hawaii.edu (Greg Lee) writes: >The subject of connecting thick-net to thin-net came up before >in this newsgroup, and it was said that you can just >stick them together directly with a connector. Following is some >of that past discussion. Thank you for the collection of past articles. Unfortunately, this splicing of Thick (Yellow) and thin (usually black) Ethernet coax cables is not an option for many sites with NeXT connection problems. Our computer center would not allow this, and I would not either if I were the caretaker of the network. The problem is NOT the connection to thick coax, but the connection to the BLUE transiver cable (containing multiple twisted-pairs) usually terminated by a 15-pin D connector. It's really a connection problem to a "DELNI-net". For this, some sort of active device is needed, and a simple connector and a splicing kit won't do. Izumi Ohzawa, izumi@violet.berkeley.edu
jacob@gore.com (Jacob Gore) (12/14/89)
In article <341@egg-idINEL.GOV> rhp@INEL.GOV (Robert Powell) writes: >It is a problem because our building is only wired with twisted-pair thick-net >ethernet. Our networking people tell me that I need a thick-net to thin-net >bridge or repeater, at a cost of around $2,600! Has anyone else out there / comp.sys.next / izumi@violet.berkeley.edu (Izumi Ohzawa) / Dec 13, 1989 / > ... I noticed several articles back about a router/bridge > made out of a cheap PC XT clone + 2 Western Digital Ethernet cards > for under $800-900. If this box can have 1 twisted-pair Ethernet > card and another thin-Ethernet card, it should do the job. > >Whoever posted that article, would you clarify this point? OK, here it is. It certainly can be done, but it's probably not the best way to do it. Your best bet is calling the supplier (or manufacturer) of your TP hub and asking them if they have a TP to Thinnet converter. I'm told that Cabletron has one for their TP for about $500 (I don't know if that is educational or "normal" price). Also, I know HP sells (or at least it did last year) an adapter that hooks in between a drop cable from a transceiver on one side and a Thinnet outlet on the other. Sorry, I don't have the part number or the price. You would still need a TP transceiver between the TP wire and the drop cable. If you do want to use a PC for this, here are the considerations: The way things are done now, you pretty much need to buy your TP transceiver and the TP hub from the same manufacturer. So, if you do buy a TP Ethernet card from Western Digital, you have to make sure that it is compatible compatible with your hub (i.e., ask them before you buy). In the likely event that it's NOT compatible with your hub, you can simply buy the standard card (WD8003E, a.k.a. "EtherCard Plus", I believe) and use the TP transceiver from your hub's vendor and a drop cable to connect to the Thicknet port on the card. The card also has a Thinnet port, so you can just buy two WD8003E. (No, you can't get by with just one card, you need one for each network.) Unless you really want to have a separate IP subnet on your side of the PC, instead of PCroute you should use its sibling, PCbridge. It is available from the same places (definitely accuvax.nwu.edu and probably uunet.uu.net). It is simpler to set up (no configuration required), and you won't end up having to assign an IP subnet just for one NeXT -- it will be on the same IP subnet as all the other hosts on that TP network. For PCbridge you may want a faster PC than for PCroute, because unlike a router, a bridge forwards every single packet it gets. Packet forwarding in PCroute/PCbridge is several times slower than packet filtering. By the way, I should mention that you do NOT need a monitor card or a monitor, as long as the boot PROMs of the PC clone you buy do not insist on checking for one (most don't). So, here are the details about how you can use a PC between networks (not the only way to do it, there is other software too). I personally would opt for a TP to Thinnet adapter from the TP vendor if it was available, and if not, I'd go for a single-port receiver from Cabletron (not the only source, but my personal favorite). A PC clone just seems like a rather bulky transceiver... Jacob -- Jacob Gore Jacob@Gore.Com boulder!gore!jacob
jacob@gore.com (Jacob Gore) (12/14/89)
Those considering using PCroute or PCbridge should read Vance Morrison's posting in comp.protocols.tcp-ip.ibmpc under subject "Re: Request for Summary Info on 'PCRoute'" (<2117@accuvax.nwu.edu>). Jacob -- Jacob Gore Jacob@Gore.Com boulder!gore!jacob
hue@netcom.UUCP (Johathan Hue) (12/14/89)
In article <1989Dec14.035818.5544@agate.berkeley.edu> izumi@violet.berkeley.edu (Izumi Ohzawa) writes: >The problem is NOT the connection to thick coax, but the >connection to the BLUE transiver cable (containing multiple >twisted-pairs) usually terminated by a 15-pin D connector. You could always do what a user here tried. Hook the transceiver up to the DSP port. Jonathan (my LANalyzer plays Bach) Hue